define_extract_agg: Define an extract request for an IPUMS aggregate data...
In ipumsr: An R Interface for Downloading, Reading, and Handling IPUMS Data

define_extract_agg

R Documentation

Define an extract request for an IPUMS aggregate data collection

Description

Define the parameters of an IPUMS aggregate data extract request to be submitted via the IPUMS API.

The IPUMS API currently supports the following aggregate data collections:

Note that not all extract request parameters and options apply to all collections. For a summary of supported features by collection, see the details below and the IPUMS API documentation.

Use get_metadata_catalog() and get_metadata() to browse and identify data sources for use in an extract definition.

Learn more about the IPUMS API in vignette("ipums-api") and aggregate data extract definitions in vignette("ipums-api-agg").

Usage

define_extract_agg(
  collection,
  description = "",
  datasets = NULL,
  time_series_tables = NULL,
  shapefiles = NULL,
  geographic_extents = NULL,
  breakdown_and_data_type_layout = NULL,
  tst_layout = NULL,
  data_format = NULL
)

Arguments

`collection`	Code for the IPUMS collection represented by this extract request. Currently, `"nhgis"` and `"ihgis"` are supported.
`description`	Description of the extract.
`datasets`	List of dataset specifications for any datasets to include in the extract request. Use `ds_spec()` to create a `ds_spec` object containing a dataset specification. See examples.
`time_series_tables`	For NHGIS extracts, list of time series table specifications for any time series tables to include in the extract request. Use `tst_spec()` to create a `tst_spec` object containing a time series table specification. See examples.
`shapefiles`	For NHGIS extracts, names of any shapefiles to include in the extract request.
`geographic_extents`	For NHGIS extracts, vector of geographic extents to use for all of the `datasets` and `time_series_tables` in the extract definition (for instance, to obtain data within a specified state). By default, selects all available extents. Use `get_metadata()` to identify the available extents for a given dataset or time series table, if any.
`breakdown_and_data_type_layout`	For NHGIS extracts, the desired layout of any `datasets` that have multiple data types or breakdown values. `"single_file"` (default) keeps all data types and breakdown values in one file `"separate_files"` splits each data type or breakdown value into its own file Required if any `datasets` included in the extract definition consist of multiple data types (for instance, estimates and margins of error) or have multiple breakdown values specified. See `get_metadata()` to determine whether a requested dataset has multiple data types.
`tst_layout`	For NHGIS extracts, the desired layout of all `time_series_tables` included in the extract definition. `"time_by_column_layout"` (wide format, default): rows correspond to geographic units, columns correspond to different times in the time series `"time_by_row_layout"` (long format): rows correspond to a single geographic unit at a single point in time `"time_by_file_layout"`: data for different times are provided in separate files Required when an extract definition includes any `time_series_tables`.
`data_format`	For NHGIS extracts, the desired format of the extract data file. `"csv_no_header"` (default) includes only a minimal header in the first row `"csv_header"` includes a second, more descriptive header row. `"fixed_width"` provides data in a fixed width format Note that by default, `read_ipums_agg()` removes the additional header row in `"csv_header"` files. Required when an extract definition includes any `datasets` or `time_series_tables`.

Details

IPUMS NHGIS

An NHGIS extract definition (collection = "nhgis") must include at least one dataset, time series table, or shapefile specification.

Create a dataset specification with ds_spec(). Each dataset must be associated with a selection of data_tables and geog_levels. Some datasets also support the selection of years and breakdown_values.

Create an NHGIS time series table specification with tst_spec(). Each time series table must be associated with a selection of geog_levels and may optionally be associated with a selection of years.

IPUMS IHGIS

An IHGIS extract definition (collection = "ihgis") must include a dataset specification. IHGIS does not support time series table or shapefile specifications.

Create a dataset specification with ds_spec(). Each dataset must be associated with a selection of data_tables and tabulation_geographies.

See examples or vignette("ipums-api-agg") for more details about specifying datasets and time series tables in an aggregate data extract definition.

Value

An object of class agg_extract containing the extract definition.

Examples

# Extract definition for tables from an NHGIS dataset
# Use `ds_spec()` to create an NHGIS dataset specification
nhgis_extract <- define_extract_agg(
  "nhgis",
  description = "Example NHGIS extract",
  datasets = ds_spec(
    "1990_STF3",
    data_tables = "NP57",
    geog_levels = c("county", "tract")
  )
)

nhgis_extract

# Extract definition for tables from an IHGIS dataset
define_extract_agg(
  "ihgis",
  description = "Example IHGIS extract",
  datasets = ds_spec(
    "KZ2009pop",
    data_tables = c("KZ2009pop.AAA", "KZ2009pop.AAB"),
    tabulation_geographies = c("KZ2009pop.g0", "KZ2009pop.g1")
  )
)

# Use `tst_spec()` to create an NHGIS time series table specification
define_extract_agg(
  "nhgis",
  description = "Example NHGIS extract",
  time_series_tables = tst_spec("CL8", geog_levels = "county"),
  tst_layout = "time_by_row_layout"
)

# To request multiple datasets, provide a list of `ds_spec` objects
define_extract_agg(
  "nhgis",
  description = "Extract definition with multiple datasets",
  datasets = list(
    ds_spec("2014_2018_ACS5a", "B01001", c("state", "county")),
    ds_spec("2015_2019_ACS5a", "B01001", c("state", "county"))
  )
)

# If you need to specify the same table or geographic level for
# many datasets, you may want to make a set of datasets before defining
# your extract request:
dataset_names <- c("2014_2018_ACS5a", "2015_2019_ACS5a")

dataset_spec <- purrr::map(
  dataset_names,
  ~ ds_spec(
    .x,
    data_tables = "B01001",
    geog_levels = c("state", "county")
  )
)

define_extract_agg(
  "nhgis",
  description = "Extract definition with multiple datasets",
  datasets = dataset_spec
)

# You can request datasets, time series tables, and shapefiles in the same
# definition:
define_extract_agg(
  "nhgis",
  description = "Extract with datasets and time series tables",
  datasets = ds_spec("1990_STF1", c("NP1", "NP2"), "county"),
  time_series_tables = tst_spec("CL6", "state"),
  shapefiles = "us_county_1990_tl2008"
)

# Geographic extents are applied to all datasets/time series tables in the
# definition
define_extract_agg(
  "nhgis",
  description = "Extent selection",
  datasets = list(
    ds_spec("2018_2022_ACS5a", "B01001", "blck_grp"),
    ds_spec("2017_2021_ACS5a", "B01001", "blck_grp")
  ),
  geographic_extents = c("010", "050")
)

# Extract specifications can be indexed by name
names(nhgis_extract$datasets)

nhgis_extract$datasets[["1990_STF3"]]

## Not run: 
# Use the extract definition to submit an extract request to the API
submit_extract(nhgis_extract)

## End(Not run)

ipumsr documentation built on June 8, 2025, 1:30 p.m.