bi_ripleys_k: Bivariate Ripley's K

In spatialTIME: Spatial Analysis of Vectra Immunoflourescent Data

Bivariate Ripley's K

Description

Bivariate Ripley's K function within spatialTIME, 'bi_ripleys_k' is a function that takes in a 'mIF' object, along with some parameters like marker names of interest and range of radii in which to assess bivariate clustering or colocalization. In 1.3.3.3 we have introduced the ability to forsgo the need for permutations with the implementation of the exact CSR estimate. This is both faster and being the exact CSR, produces an exact degree of clustering in the spatial files.

Due to the availability of whole slide images (WSI), there's a possibility users will be running bivariate Ripley's K on samples that have millions of cells. When doing this, keep in mind that a nearest neighbor matrix with *n* cell is *n* by *n* in size and therefore easily consumers high performance compute levels of RAM. To combat this, we have implemented a tiling method that performs counts for small chunks of the distance matrix at a time before finally calculating the bivariate Ripley's K value on the total counts. When doing this there are now 2 import parameters to keep in mind. The 'big' parameter is the size of the tile to use. We have found 1000 to be a good number that allows for high number of cores while maintaining low RAM usage. The other important parameter when working with WSI is nlarge which is the fall over for switching to no edge correction. The spatstat.explore::Kest univariate Ripley's K uses a default of 3000 but we have defaulted to 1000 to keep compute minimized as edge correction uses large amounts of RAM over 'none'.

Usage

bi_ripleys_k(
  mif,
  mnames,
  r_range = 0:100,
  edge_correction = "translation",
  num_permutations = 50,
  permute = FALSE,
  keep_permutation_distribution = FALSE,
  overwrite = TRUE,
  workers = 6,
  big = 1000,
  nlarge = 1000,
  xloc = NULL,
  yloc = NULL
)

Arguments

mif	mIF object with spatial data frames, clinical, and per-sample summary information
mnames	vector of column names for phenotypes or data frame of marker combinations
r_range	vector range of radii to calculate co-localization *K*
edge_correction	character edge_correction method, one of "translation", "border", "or none"
num_permutations	integer number of permutations to estimate CSR
permute	whether or not to use permutations to estimate CSR (TRUE) or to calculate exact CSR (FALSE)
keep_permutation_distribution	boolean as to whether to summarise permutations to mean
overwrite	boolean as to whether to replace existing bivariate_Count if exists
workers	integer number of CPU workers to use
big	integer used as the threshold for subsetting large samples, default is 1000 either *i* or *j*
nlarge	number of cells in either *i* or *j* to flip to no edge correction - at small (relative to whole spatial region) *r* values differences in results between correction methods is negligible so running a few samples is recommended. Perhaps compute outweighs small differences in correction methods.
xloc	the x and y positions that correspond to cells. If left as NULL, XMin, XMax, YMin, and YMax must be present in the spatial files
yloc	the x and y positions that correspond to cells. If left as NULL, XMin, XMax, YMin, and YMax must be present in the spatial files

Value

mif object with bivariate Ripley's K calculated

Examples

x <- spatialTIME::create_mif(clinical_data = spatialTIME::example_clinical %>% 
                               dplyr::mutate(deidentified_id = as.character(deidentified_id)),
                             sample_data = spatialTIME::example_summary %>% 
                               dplyr::mutate(deidentified_id = as.character(deidentified_id)),
                             spatial_list = spatialTIME::example_spatial,
                             patient_id = "deidentified_id", 
                             sample_id = "deidentified_sample")
mnames_good <- c("CD3..Opal.570..Positive","CD8..Opal.520..Positive",
                 "FOXP3..Opal.620..Positive","PDL1..Opal.540..Positive",
                 "PD1..Opal.650..Positive","CD3..CD8.","CD3..FOXP3.")
x2 = bi_ripleys_k(mif = x, mnames = mnames_good[1:2], 
                   r_range = 0:100, edge_correction = "none", permute = FALSE,
                   num_permutations = 50, keep_permutation_distribution = FALSE, 
                   workers = 1, big = 1000)

spatialTIME documentation built on April 1, 2023, 12:18 a.m.