calabrialab/ISAnalytics
Analyze gene therapy vector insertion sites data identified from genomics next generation sequencing reads for clonal tracking studies

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In calabrialab/ISAnalytics: Analyze gene therapy vector insertion sites data identified from genomics next generation sequencing reads for clonal tracking studies 

knitr::opts_chunk$set(
    collapse = TRUE,
    comment = "#>",
    crop = NULL
    ## Related to
    ## https://stat.ethz.ch/pipermail/bioc-devel/2020-April/016656.html
)

## Bib setup
library("RefManageR")

## Write bibliography information
bib <- c(
    R = citation(),
    BiocStyle = citation("BiocStyle")[1],
    knitr = citation("knitr")[1],
    RefManageR = citation("RefManageR")[1],
    rmarkdown = citation("rmarkdown")[1],
    sessioninfo = citation("sessioninfo")[1],
    testthat = citation("testthat")[1],
    ISAnalytics = citation("ISAnalytics")[1],
    VISPA2 = BibEntry(
        bibtype = "Article",
        title = paste(
            "VISPA2: a scalable pipeline for",
            "high-throughput identification and",
            "annotation of vector integration sites"
        ),
        author = "Giulio Spinozzi, Andrea Calabria, Stefano Brasca",
        journaltitle = "BMC Bioinformatics",
        date = "2017-11-25",
        doi = "10.1186/s12859-017-1937-9"
    ),
    eulerr = citation("eulerr")[1]
)

library(ISAnalytics)
library(BiocStyle)
library(DT)
main_fig <- fs::path("../man", "figures", "dyn_vars_general.png")

Introduction

ISAnalytics is an R package developed to analyze gene therapy vector insertion sites data identified from genomics next generation sequencing reads for clonal tracking studies.

In this vignette we will explain how to properly setup the workflow and the first steps of data import and data cleaning.

Setting up your workflow with dynamic vars

This section demonstrates how to properly setup your workflow with ISAnalytics using the "dynamic vars" system.

From ISAnalytics 1.5.4 onwards, a new system here referred to as "dynamic vars" has been implemented to improve the flexibility of the package, by allowing multiple input formats based on user needs rather than enforcing hard-coded names and structures. In this way, users that do not follow the standard name conventions used by the package have to put minimal effort into making their inputs compliant to the package requirements.

There are 5 main categories of inputs you can customize:

General approach

The general approach is based on the specification of predefined tags and their associated information in the form of simple data frames with a standard structure, namely:

names | types | transform | flag | tag ---------------------|--------|--------------------|--------|----- <name of the column> | <type> | <a lambda or NULL> | <flag> | <tag>

where

Dynamic variables general approach

Tags

As already mentioned, certain functions included in the package require the presence of specific tags (and associated column names) in the input to work properly. You can always check what a tag means and where it is used by using the function inspect_tags() and providing in input the tags you want to check as a character vector.

inspect_tags("chromosome")

You should make sure the tag matches the right information in your inputs by looking at the description of the tag. It is also possible to add entries that are not associated with any tag. Here is an overview of the critical tags for each category.

Mandatory IS vars

all_tags <- available_tags()
all_tags <- all_tags |>
    dplyr::mutate(needed_in = purrr::map_chr(
        .data$needed_in,
        ~ paste0(.x, collapse = ", ")
    ))
mand_tags <- all_tags |>
    dplyr::filter(.data$dyn_vars_tbl == "mand_vars") |>
    dplyr::select(dplyr::all_of(c("tag", "needed_in", "description")))
annot_tags <- all_tags |>
    dplyr::filter(.data$dyn_vars_tbl == "annot_vars") |>
    dplyr::select(dplyr::all_of(c("tag", "needed_in", "description")))
af_tags <- all_tags |>
    dplyr::filter(.data$dyn_vars_tbl == "af_vars") |>
    dplyr::select(dplyr::all_of(c("tag", "needed_in", "description")))
iss_tags <- all_tags |>
    dplyr::filter(.data$dyn_vars_tbl == "iss_vars") |>
    dplyr::select(dplyr::all_of(c("tag", "needed_in", "description")))

datatable(
    mand_tags,
    class = "stripe",
    options = list(dom = "t"),
    rownames = FALSE
)

The presence of all mandatory IS vars is also checked and used in other functions - for example, when importing matrices it is ensured that all mandatory variables are present in the input, as declared in the look up table. Some functions may require information that needs to be specified as input, always check the documentation if you have doubts.

Annotation IS vars

datatable(
    annot_tags,
    class = "stripe",
    options = list(dom = "t"),
    rownames = FALSE
)

Although genomic annotations are not necessarily required to work with ISAnalytics, some operations do require annotation - if you're working with matrices that are not annotated you can either annotate them with a tool of your choice or skip the steps that require annotation.

Association file columns

datatable(
    af_tags,
    class = "stripe",
    options = list(dom = "t"),
    rownames = FALSE
)

Some tags in this table are not associated with any function yet, but they exist for potential new features that will be added in the future.

VISPA2 stats specs

datatable(
    iss_tags,
    class = "stripe",
    options = list(dom = "t"),
    rownames = FALSE
)

NOTE: VISPA2 stats files usually follow standard naming conventions. If the pipeline launch was configured with default parameters, do not change this lookup table.

Customizing dynamic vars

For each category of dynamic vars there are 3 functions:

Setters will take in input the new variables, validate and eventually change the lookup table. If validation fails an error will be thrown instead, inviting the user to review the inputs. Moreover, if some of the critical tags for the category are missing, a warning appears, with a list of the missing ones.

Let's take a look at some examples.

On package loading, all lookup tables are set to default values. For example, for mandatory IS vars we have:

mandatory_IS_vars(TRUE)

Let's suppose our matrices follow a different standard, and integration events are characterized by 5 fields, like so (the example contains random data):

chrom | position | strand | gap | junction --------|----------|--------|--------|--------- "chr1" | 342543 | "+" | 100 | 50 ... | ... | ... | ... | ...

To make this work with ISAnalytics functions, we need to compile the lookup table like this:

new_mand_vars <- tibble::tribble(
    ~names, ~types, ~transform, ~flag, ~tag,
    "chrom", "char", ~ stringr::str_replace_all(.x, "chr", ""), "required",
    "chromosome",
    "position", "int", NULL, "required", "locus",
    "strand", "char", NULL, "required", "is_strand",
    "gap", "int", NULL, "required", NA_character_,
    "junction", "int", NULL, "required", NA_character_
)

Notice that we have specified a transformation for the "chromosome" tag: in this case we would like to have only the number of the chromosome without the prefix "chr" - this lambda will get executed immediately after import.

To set the new variables simply do:

set_mandatory_IS_vars(new_mand_vars)
mandatory_IS_vars(TRUE)

If you don't specify a critical tag, a warning message is displayed:

new_mand_vars[1, ]$tag <- NA_character_
set_mandatory_IS_vars(new_mand_vars)
mandatory_IS_vars(TRUE)

If you change your mind and want to go back to defaults:

reset_mandatory_IS_vars()
mandatory_IS_vars(TRUE)

The principle is the same for annotation IS vars, association file columns and VISPA2 stats specs. Here is a summary of the functions for each:

Matrix files suffixes work slightly different:

matrix_file_suffixes()

To change this lookup table use the function set_matrix_file_suffixes(): the function will ask to specify a suffix for each quantification and for both annotated and not annotated versions. These suffixes are used in the automated matrix import function when scanning the file system.

To reset all lookup tables to their default configurations you can also use the function reset_dyn_vars_config(), which reverts all changes.

FAQs

Do I have to do this every time the package loads?

No, if you frequently have to work with a non-standard settings profile, you can use the functions export_ISA_settings() and import_ISA_settings(): these functions allow the import/export of setting profiles in *.json format.

Once you set your variables for the first time through the procedure described before, simply call the export function and all will be saved to a json file, which can then be imported for the next workflow.

Reporting progress

From ISAnalytics 1.7.4, functions that make use of parallel workers or process long tasks report progress via the functions offered by progressr. To enable progress bars for all functions in ISAnalytics do

enable_progress_bars()

before calling other functions. For customizing the appearance of the progress bar please refer to progressr documentation.

Introduction to ISAnalytics import functions family

In this section we're going to explain more in detail how functions of the import family should be used, the most common workflows to follow and more.

Designed to work with VISPA2 pipeline

The vast majority of the functions included in this package is designed to work in combination with VISPA2 pipeline r Citep(bib[["VISPA2"]]). If you don't know what it is, we strongly recommend you to take a look at these links:

File system structure generated

VISPA2 produces a standard file system structure starting from a folder you specify as your workbench or root. The structure always follows this schema:

Most of the functions implemented expect a standard file system structure as the one described above.

Notation {#notation}

We call an "integration matrix" a tabular structure characterized by:

sample_sparse_matrix <- tibble::tribble(
    ~chr, ~integration_locus, ~strand, ~GeneName, ~GeneStrand,
    ~exp1, ~exp2, ~exp3,
    "1", 12324, "+", "NFATC3", "+", 4553, 5345, NA_integer_,
    "6", 657532, "+", "LOC100507487", "+", 76, 545, 5,
    "7", 657532, "+", "EDIL3", "-", NA_integer_, 56, NA_integer_,
)
print(sample_sparse_matrix, width = Inf)

The package uses a more compact form of these matrices, limiting the amount of NA values and optimizing time and memory consumption. For more info on this take a look at: Tidy data

While integration matrices contain the actual data, we also need associated sample metadata to perform the vast majority of the analyses. ISAnalytics expects the metadata to be contained in a so called "association file", which is a simple tabular file.

To generate a blank association file you can use the function generate_blank_association_file. You can also view the standard column names with association_file_columns().

Importing metadata {#metadata}

To import metadata we use import_association_file(). This function is not only responsible for reading the file into the R environment as a data frame, but it is capable to perform a file system alignment operation, that is, for each project and pool contained in the file, it scans the file system starting from the provided root to check if the corresponding folders (contained in the appropriate column) can be found. Remember that to work properly, this operation expects a standard folder structure, such as the one provided by VISPA2. This function also produces an interactive HTML report.

fs_path <- generate_default_folder_structure()
withr::with_options(list(ISAnalytics.reports = FALSE), code = {
    af <- import_association_file(fs_path$af, root = fs_path$root)
})

print(head(af))

Function arguments

You can change several arguments in the function call to modify the behavior of the function.

For further details view the dedicated function documentation.

NOTE: the function supports files in various formats as long as the correct separator is provided. It also accepts files in *.xlsx and *.xls formats but we do not recommend using these since the report won't include a detailed summary of potential parsing problems.

The interactive report includes useful information such as

Importing VISPA2 stats files

VISPA2 automatically produces summary files for each pool holding information that can be useful for other analyses downstream, so it is recommended to import them in the first steps of the workflow. To do that, you can use import_VISPA2_stats:

vispa_stats <- import_Vispa2_stats(
    association_file = af,
    join_with_af = FALSE,
    report_path = NULL
)

print(head(vispa_stats))

The function requires as input the imported and file system aligned association file and it will scan the iss folder for files that match some known prefixes (defaults are already provided but you can change them as you see fit). You can either choose to join the imported data frames with the association file in input and obtain a single data frame or keep it as it is, just set the parameter join_with_af accordingly. At the end of the process an HTML report is produced, signaling potential problems.

You can directly call this function when you import the association file by setting the import_iss argument of import_association_file to TRUE.

Importing a single integration matrix

If you want to import a single integration matrix you can do so by using the import_single_Vispa2Matrix() function. This function reads the file and converts it into a tidy structure: several different formats can be read, since you can specify the column separator.

matrix_path <- fs::path(
    fs_path$root,
    "PJ01",
    "quantification",
    "POOL01-1",
    "PJ01_POOL01-1_seqCount_matrix.no0.annotated.tsv.gz"
)
matrix <- import_single_Vispa2Matrix(matrix_path)

matrix

For details on usage and arguments view the dedicated function documentation.

Automated integration matrices import

Integration matrices import can be automated when when the association file is imported with the file system alignment option. ISAnalytics provides a function, import_parallel_Vispa2Matrices(), that allows to do just that in a fast and efficient way.

withr::with_options(list(ISAnalytics.reports = FALSE), {
    matrices <- import_parallel_Vispa2Matrices(af,
        c("seqCount", "fragmentEstimate"),
        mode = "AUTO"
    )
})

Function arguments

Let's see how the behavior of the function changes when we change arguments.

association_file argument

You can supply a data frame object, imported via import_association_file() (see Section \@ref(metadata)) or a string (the path to the association file on disk). In the first scenario it is necessary to perform file system alignment, since the function scans the folders contained in the column Path_quant, while in the second case you should also provide as additional named argument (to ...) an appropriate root: the function will internally call import_association_file(), if you don't have specific needs we recommend doing the 2 steps separately and provide the association file as a data frame.

quantification_type argument

For each pool there may be multiple available quantification types, that is, different matrices containing the same samples and same genomic features but a different quantification. A typical workflow contemplates seqCount and fragmentEstimate, all the supported quantification types can be viewed with quantification_types().

matrix_type argument

As we mentioned in Section \@ref(notation), annotation columns are optional and may not be included in some matrices. This argument allows you to specify the function to look for only a specific type of matrix, either annotated or not_annotated.

File suffixes for matrices are specified via matrix_file_suffixes().

workers argument

Sets the number of parallel workers to set up. This highly depends on the hardware configuration of your machine.

multi_quant_matrix argument

When importing more than one quantification at once, it can be very handy to have all data in a single data frame rather than two. If set to TRUE the function will internally call comparison_matrix() and produce a single data frames that has a dedicated column for each quantification. For example, for the matrices we've imported before:

print(head(matrices))

report_path argument

As other import functions, also import_parallel_Vispa2Matrices() produces an interactive report, use this argument to set the appropriate path were the report should be saved.

mode argument

Since ISAnalytics 1.8.3 this argument can only be set to AUTO.

What do you want to import?
In a fully automated mode, the function will try to import everything that is contained in the input association file. This means that if you need to import only a specific set of projects/pools, you will need to filter the association file accordingly prior calling the function (you can easily do that via the filter_for argument as explained in Section \@ref(metadata)).

How to deal with duplicates?
When scanning folders for files that match a given pattern (in our case the function looks for matrices that match the quantification type and the matrix type), it is very possible that the same folder contains multiple files for the same quantification. Of course this is not recommended, we suggest to move the duplicated files in a sub directory or remove them if they're not necessary, but in case this happens, you need to set two other arguments (described in the next sub sections) to "help" the function discriminate between duplicates. Please note that if such discrimination is not possible no files are imported.

patterns argument

Providing a set of patterns (interpreted as regular expressions) helps the function to choose between duplicated files if any are found. If you're confident your folders don't contain any duplicates feel free to ignore this argument.

matching_opt argument

This argument is relevant only if patterns isn't NULL. Tells the function how to match the given patterns if multiple are supplied: ALL means keep only those files whose name matches all the given patterns, ANY means keep only those files whose name matches any of the given patterns and OPTIONAL expresses a preference, try to find files that contain the patterns and if you don't find any return whatever you find.

... argument

Additional named arguments to supply to comparison_matrix() and import_single_Vispa2_matrix

Notes

Earlier versions of the package featured two separated functions, import_parallel_Vispa2Matrices_auto() and import_parallel_Vispa2Matrices_interactive(). Those functions are now officially deprecated (since ISAnalytics 1.3.3) and will be defunct on the next release cycle.

Data cleaning and pre-processing

This section goes more in detail on some data cleaning and pre-processing operations you can perform with this package.

ISAnalytics offers several different functions for cleaning and pre-processing your data.

Removing collisions

In this section we illustrate the functions dedicated to collision removal.

What is a collision and why should you care?

We're not going into too much detail here, but we're going to explain in a very simple way what a "collision" is and how the function in this package deals with them.

We say that an integration (aka a unique combination of mandatory_IS_vars()) is a collision if this combination is shared between different independent samples: an independent sample is a unique combination of metadata fields specified by the user. The reason behind this is that it's highly improbable to observe the very same integration in two different independent samples and this phenomenon might be an indicator of some kind of contamination in the sequencing phase or in PCR phase, for this reason we might want to exclude such contamination from our analysis. ISAnalytics provides a function that processes the imported data for the removal or reassignment of these "problematic" integrations, remove_collisions().

The processing is done using the sequence count value, so the corresponding matrix is needed for this operation.

The logic behind the function

The remove_collisions() function follows several logical steps to decide whether an integration is a collision and if it is it decides whether to re-assign it or remove it entirely based on different criteria.

Identifying the collisions

The function uses the information stored in the association file to assess which independent samples are present and counts the number of independent samples for each integration: those who have a count > 1 are considered collisions.

library(ISAnalytics)
ex_coll <- tibble::tribble(
    ~chr, ~integration_locus, ~strand, ~seqCount, ~CompleteAmplificationID,
    ~SubjectID, ~ProjectID,
    "1", 123454, "+", 653, "SAMPLE1", "SUBJ01", "PJ01",
    "1", 123454, "+", 456, "SAMPLE2", "SUBJ02", "PJ01"
)
knitr::kable(ex_coll, caption = paste(
    "Example of collisions: the same",
    "integration (1, 123454, +) is found",
    "in 2 different independent samples",
    "((SUBJ01, PJ01) & (SUBJ02, PJ01))"
))

Re-assign vs remove

Once the collisions are identified, the function follows 3 steps where it tries to re-assign the combination to a single independent sample. The criteria are:

  1. Compare dates: if it's possible to have an absolute ordering on dates, the integration is re-assigned to the sample that has the earliest date. If two samples share the same date it's impossible to decide, so the next criteria is tested
  2. Compare replicate number: if a sample has the same integration in more than one replicate, it's more probable the integration is not an artifact. If it's possible to have an absolute ordering, the collision is re-assigned to the sample whose grouping is largest
  3. Compare the sequence count value: if the previous criteria wasn't sufficient to make a decision, for each group of independent samples it's evaluated the sum of the sequence count value - for each group there is a cumulative value of the sequence count and this is compared to the value of other groups. If there is a single group which has a ratio n times bigger than other groups, this one is chosen for re-assignment. The factor n is passed as a parameter in the function (reads_ratio), the default value is 10.

If none of the criteria were sufficient to make a decision, the integration is simply removed from the matrix.

Usage

data("integration_matrices", package = "ISAnalytics")
data("association_file", package = "ISAnalytics")
## Multi quantification matrix
no_coll <- remove_collisions(
    x = integration_matrices,
    association_file = association_file,
    report_path = NULL
)
## Matrix list
separated <- separate_quant_matrices(integration_matrices)
no_coll_list <- remove_collisions(
    x = separated,
    association_file = association_file,
    report_path = NULL
)
## Only sequence count
no_coll_single <- remove_collisions(
    x = separated$seqCount,
    association_file = association_file,
    quant_cols = c(seqCount = "Value"),
    report_path = NULL
)

Important notes on the association file:

The function accepts different inputs, namely:

If the option ISAnalytics.reports is active, an interactive report in HTML format will be produced at the specified path.

Re-align other matrices

If you've given as input the standalone sequence count matrix to remove_collisions(), to realign other matrices you have to call the function realign_after_collisions(), passing as input the processed sequence count matrix and the named list of other matrices to realign. NOTE: the names in the list must be quantification types.

other_realigned <- realign_after_collisions(
    sc_matrix = no_coll_single,
    other_matrices = list(fragmentEstimate = separated$fragmentEstimate)
)

Performing data and metadata aggregation

In this section we're going to explain in detail how to use functions of the aggregate family, namely:

  1. aggregate_metadata()
  2. aggregate_values_by_key()

Aggregating metadata

We refer to information contained in the association file as "metadata": sometimes it's useful to obtain collective information based on a certain group of variables we're interested in. The function aggregate_metadata() does just that: according to the grouping variables, meaning the names of the columns in the association file to perform a group_by operation with,it creates a summary. You can fully customize the summary by providing a "function table" that tells the function which operation should be applied to which column and what name to give to the output column. A default is already supplied:

library(ISAnalytics)
print(default_meta_agg(), width = Inf)

You can either provide purrr-style lambdas (as given in the example above), or simply specify the name of the function and additional parameters as a list in a separated column. If you choose to provide your own table you should maintain the column names for the function to work properly. For more details on this take a look at the function documentation ?default_meta_agg.

Typical workflow

  1. Import the association file via import_assocition_file(). If you need more information on import function please view the vignette "How to use import functions": vignette("how_to_import_functions", package="ISAnalytics").
  2. Perform aggregation
data("association_file", package = "ISAnalytics")
aggregated_meta <- aggregate_metadata(association_file = association_file)

print(aggregated_meta)

Aggregation of values by key

ISAnalytics contains useful functions to aggregate the values contained in your imported matrices based on a key, aka a single column or a combination of columns contained in the association file that are related to the samples.

Typical workflow

  1. Import your association file
  2. Import integration matrices via import_parallel_Vispa2Matrices()
  3. Perform aggregation
data("integration_matrices", package = "ISAnalytics")
data("association_file", package = "ISAnalytics")
aggreg <- aggregate_values_by_key(
    x = integration_matrices,
    association_file = association_file,
    value_cols = c("seqCount", "fragmentEstimate")
)

print(aggreg, width = Inf)

The function aggregate_values_by_key can perform the aggregation both on the list of matrices and a single matrix.

Changing parameters to obtain different results

The function has several different parameters that have default values that can be changed according to user preference.

  1. Changing the key value
    You can change the value of the parameter key as you see fit. This parameter should contain one or multiple columns of the association file that you want to include in the grouping when performing the aggregation. The default value is set to c("SubjectID", "CellMarker", "Tissue", "TimePoint") (same default key as the aggregate_metadata function).
agg1 <- aggregate_values_by_key(
    x = integration_matrices,
    association_file = association_file,
    key = c("SubjectID", "ProjectID"),
    value_cols = c("seqCount", "fragmentEstimate")
)

print(agg1, width = Inf)
  1. Changing the lambda value
    The lambda parameter indicates the function(s) to be applied to the values for aggregation. lambda must be a named list of either functions or purrr-style lambdas: if you would like to specify additional parameters to the function the second option is recommended. The only important note on functions is that they should perform some kind of aggregation on numeric values: this means in practical terms they need to accept a vector of numeric/integer values as input and produce a SINGLE value as output. Valid options for this purpose might be: sum, mean, median, min, max and so on.
agg2 <- aggregate_values_by_key(
    x = integration_matrices,
    association_file = association_file,
    key = "SubjectID",
    lambda = list(mean = ~ mean(.x, na.rm = TRUE)),
    value_cols = c("seqCount", "fragmentEstimate")
)

print(agg2, width = Inf)

Note that, when specifying purrr-style lambdas (formulas), the first parameter needs to be set to .x, other parameters can be set as usual.

You can also use in lambda functions that produce data frames or lists. In this case all variables from the produced data frame will be included in the final data frame. For example:

agg3 <- aggregate_values_by_key(
    x = integration_matrices,
    association_file = association_file,
    key = "SubjectID",
    lambda = list(describe = ~ list(psych::describe(.x))),
    value_cols = c("seqCount", "fragmentEstimate")
)

print(agg3, width = Inf)
  1. Changing the value_cols value
    The value_cols parameter tells the function on which numeric columns of x the functions should be applied. Note that every function contained in lambda will be applied to every column in value_cols: resulting columns will be named as "original name_function applied".
agg4 <- aggregate_values_by_key(
    x = integration_matrices,
    association_file = association_file,
    key = "SubjectID",
    lambda = list(sum = sum, mean = mean),
    value_cols = c("seqCount", "fragmentEstimate")
)

print(agg4, width = Inf)
  1. Changing the group value
    The group parameter should contain all other variables to include in the grouping besides key. By default this contains c("chr", "integration_locus","strand", "GeneName", "GeneStrand"). You can change this grouping as you see fit, if you don't want to add any other variable to the key, just set it to NULL.
agg5 <- aggregate_values_by_key(
    x = integration_matrices,
    association_file = association_file,
    key = "SubjectID",
    lambda = list(sum = sum, mean = mean),
    group = c(mandatory_IS_vars()),
    value_cols = c("seqCount", "fragmentEstimate")
)

print(agg5, width = Inf)

Analysis use-case example: shared integration sites

An integration site is always characterized by a triple of values: (chr, integration_locus, strand), hence these attributes are always present in integration matrices.

We can aggregate our data in different ways according to our needs, obtaining therefore different groups. Each group has an associated set of integration sites.

NOTE: aggregating data is not mandatory, since sharing functions in ISAnalytics only count distinct integration sites and do not require any quantification. The only important thing is that columns that are included in the specified key are also included in the input matrices.

## Aggregation by standard key
agg <- aggregate_values_by_key(integration_matrices,
    association_file,
    value_cols = c("seqCount", "fragmentEstimate")
)
agg <- agg |> dplyr::filter(TimePoint %in% c("0030", "0060"))

print(agg, width = Inf)

An integration site is shared between two or more groups if the same triple is observed in all the groups considered.

Automated sharing counts

ISAnalytics provides the function is_sharing() for computing automated sharing counts. The function has several arguments that can be tuned according to user needs.

SCENARIO 1: single input data frame and single grouping key

sharing_1 <- is_sharing(agg,
    group_key = c(
        "SubjectID", "CellMarker",
        "Tissue", "TimePoint"
    ),
    n_comp = 2,
    is_count = TRUE,
    relative_is_sharing = TRUE,
    minimal = TRUE,
    include_self_comp = FALSE,
    keep_genomic_coord = TRUE
)
sharing_1

In this configuration we set:

Changing the number of comparisons

sharing_1_a <- is_sharing(agg,
    group_key = c(
        "SubjectID", "CellMarker",
        "Tissue", "TimePoint"
    ),
    n_comp = 3,
    is_count = TRUE,
    relative_is_sharing = TRUE,
    minimal = TRUE,
    include_self_comp = FALSE,
    keep_genomic_coord = TRUE
)
sharing_1_a

Changing the n_comp to 3 means that we want to calculate the sharing between 3 different groups. Note that the shared column contains the counts of integrations that are shared by ALL groups, which is equivalent to a set intersection.

Beware of the fact that the more comparisons are requested the more time the computation requires.

A case when it is useful to set minimal = FALSE

Setting minimal = FALSE produces all possible permutations of the groups and the corresponding values. In combination with include_self_comp = TRUE, this is useful when we want to know the sharing between pairs of groups and plot results as a heatmap.

sharing_1_b <- is_sharing(agg,
    group_key = c(
        "SubjectID", "CellMarker",
        "Tissue", "TimePoint"
    ),
    n_comp = 2,
    is_count = TRUE,
    relative_is_sharing = TRUE,
    minimal = FALSE,
    include_self_comp = TRUE
)
sharing_1_b
heatmaps <- sharing_heatmap(sharing_1_b)

The function sharing_heatmap() automatically plots sharing between 2 groups. There are several arguments to this function that allow us to obtain heatmaps for the absolute sharing values or the relative (percentage) values.

heatmaps$absolute
heatmaps$on_g1
heatmaps$on_union

Beware of the fact that calculating all permutations takes longer than calculating only distinct combinations, therefore if you don't need your results plotted or you have more than 2 groups to compare you should stick with minimal = TRUE and include_self_comp = FALSE.

SCENARIO 2: single input data frame and multiple grouping keys

In the first scenario, groups were homogeneous, that is, they were grouped all with the same key. In this other scenario we want to start with data contained in just one data frame but we want to compare sets of integrations that are grouped differently. To do this we give as input a list of keys through the argument group_keys.

sharing_2 <- is_sharing(agg,
    group_keys = list(
        g1 = c(
            "SubjectID", "CellMarker",
            "Tissue", "TimePoint"
        ),
        g2 = c("SubjectID", "CellMarker"),
        g3 = c("CellMarker", "Tissue")
    )
)
sharing_2

There are a few things to keep in mind in this case:

SCENARIO 3: multiple input data frame and single grouping key

Providing multiple input data frames and the same grouping key is an effective way to reduce the number of comparisons performed. Let's make an example: suppose we're interested in comparing groups labelled by a unique combination of SubjectID, CellMarker, Tissue and TimePoint, but this time we want the first group to contain only integrations relative to PT001_MNC_BM_0030 and the second group to contain only integrations relative to PT001_MNC_BM_0060.

We're going to filter the original data frame in order to obtain only relevant data in 2 separated tables and then proceed by calling the function.

first_sample <- agg |>
    dplyr::filter(
        SubjectID == "PT001", CellMarker == "MNC", Tissue == "BM",
        TimePoint == "0030"
    )
second_sample <- agg |>
    dplyr::filter(
        SubjectID == "PT001", CellMarker == "MNC", Tissue == "BM",
        TimePoint == "0060"
    )
sharing_3 <- is_sharing(first_sample, second_sample,
    group_key = c(
        "SubjectID", "CellMarker",
        "Tissue", "TimePoint"
    ),
    is_count = TRUE,
    relative_is_sharing = TRUE,
    minimal = TRUE
)
sharing_3

Once again the arguments n_comp and include_self_comp are ignored: the number of comparisons is equal to the number of data frames in input.

To handle special limit cases, the output group ids are appended with a dash and a number (-1, -2, ...) that indicates the data frame of origin: this is useful in the case group ids are duplicated in the inputs. To understand better let's make an example:

sharing_3_a <- is_sharing(
    first_sample, second_sample,
    group_key = c(
        "CellMarker", "Tissue"
    ),
    is_count = TRUE,
    relative_is_sharing = TRUE,
    minimal = FALSE
)
sharing_3_a

As you can see, the IDs of group 1 and group 2 are duplicated and without a suffix it would be impossible to know which one came from which data frame. In this way we know that the group "MNC_BM-1" comes from table 1 and has 54 ISs, while "MNC_BM-2" comes from the second input table and has 114 ISs.

SCENARIO 4: multiple input data frame and multiple grouping keys

Finally, the most general scenario is when we have multiple data frames with multiple keys. In this case the number of data frames must be equal to the number of provided keys and grouping keys are applied in order ( data frame 1 is grouped with key 1, data frame 2 is grouped with key 2, and so on).

df1 <- agg |>
    dplyr::filter(TimePoint == "0030")
df2 <- agg |>
    dplyr::filter(TimePoint == "0060")
df3 <- agg |>
    dplyr::filter(Tissue == "BM")

keys <- list(
    g1 = c("SubjectID", "CellMarker", "Tissue"),
    g2 = c("SubjectID", "Tissue"),
    g3 = c("SubjectID", "CellMarker", "Tissue")
)

sharing_4 <- is_sharing(df1, df2, df3, group_keys = keys)
sharing_4

Notice that in this example the keys for g1 and g3 are the same, meaning the labels of the groups are actually the same, however you should remember that the groups contain a different set of integration sites since they come from different data frames.

Plotting sharing results

When we have more than 2 comparisons it is convenient to plot them as venn or euler diagrams. ISAnalytics has a fast way to do that through the functions is_sharing() and sharing_venn().

sharing_5 <- is_sharing(agg,
    group_keys = list(
        g1 = c(
            "SubjectID", "CellMarker",
            "Tissue", "TimePoint"
        ),
        g2 = c("SubjectID", "CellMarker"),
        g3 = c("CellMarker", "Tissue")
    ), table_for_venn = TRUE
)
sharing_5

The argument table_for_venn = TRUE will add a new column truth_tbl_venn that contains corresponding truth tables for each row.

sharing_plots1 <- sharing_venn(sharing_5, row_range = 1, euler = TRUE)
sharing_plots2 <- sharing_venn(sharing_5, row_range = 1, euler = FALSE)

Say that we're interested in plotting just the first row of our sharing data frame. Then we can call the function sharing_venn and specify in the row_range argument the index 1. Note that this function requires the package r CRANpkg("eulerr") to work. The argument euler indicates if the function should produce euler or venn diagrams instead.

Once obtained the lists of euler/venn objects we can plot them by simply calling the function plot():

plot(sharing_plots1[[1]])
plot(sharing_plots2[[1]])

There are several options that can be set, for this please refer to eulerr docs.

Reproducibility

R session information.

## Session info
library("sessioninfo")
options(width = 120)
session_info()

Bibliography

This vignette was generated using r Biocpkg("BiocStyle") r Citep(bib[["BiocStyle"]]) with r CRANpkg("knitr") r Citep(bib[["knitr"]]) and r CRANpkg("rmarkdown") r Citep(bib[["rmarkdown"]]) running behind the scenes.

Citations made with r CRANpkg("RefManageR") r Citep(bib[["RefManageR"]]).

## Print bibliography
PrintBibliography(bib, .opts = list(hyperlink = "to.doc", style = "html"))


calabrialab/ISAnalytics documentation built on Nov. 2, 2023, 8:57 p.m.

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