Compare two releases of a UCDP dataset — ucdp_compare

ucdp_compare_versions() identifies observations and values that were added, removed, or revised between two UCDP releases. It can download both releases or compare data frames that have already been imported.

Usage

ucdp_compare_versions(
  dataset,
  old_version,
  new_version,
  variant = NULL,
  format = "csv",
  key = NULL,
  columns = NULL,
  ignore = "version",
  tolerance = sqrt(.Machine$double.eps),
  detail = c("rows", "cells", "summary"),
  old_data = NULL,
  new_data = NULL,
  quiet = FALSE,
  ...
)

Arguments

dataset: Dataset name or alias accepted by ucdp_get().
old_version, new_version: Exact release identifiers.
variant: Optional dataset variant, such as "dyadic".
format: Download format. CSV is recommended for stable comparisons.
key: Character vector of columns that uniquely identify observations. When NULL, a key is inferred and verified for uniqueness in both data sets.
columns: Columns whose values should be compared. The default compares all columns shared by the releases except key and ignored columns.
ignore: Columns to exclude from value comparisons. The release-level version column is ignored by default because it necessarily differs.
tolerance: Relative tolerance for comparisons between numeric values.
detail: Return "rows" (the default), cell-level changes with "cells", or only summaries with "summary".
old_data, new_data: Optional preloaded data frames. Supply both or neither. This is useful when releases have already been downloaded.
quiet: Suppress download messages?
...: Additional arguments passed to ucdp_get() for both releases.

Value

An object of class ucdp_version_comparison. Its components include overview, variables, added, removed, modified, cell_changes, and metadata.

Examples

old <- data.frame(id = 1:3, deaths = c(1, 2, 3), version = "1.0")
new <- data.frame(id = 2:4, deaths = c(2, 4, 1), version = "2.0")
comparison <- ucdp_compare_versions(
  "ged", "1.0", "2.0", key = "id",
  old_data = old, new_data = new
)
comparison$overview
#> # A tibble: 1 × 7
#>   old_rows new_rows matched added removed modified unchanged
#>      <int>    <int>   <int> <int>   <int>    <int>     <int>
#> 1        3        3       2     1       1        1         1

if (FALSE) { # \dontrun{
comparison <- ucdp_compare_versions("ged", "24.1", "25.1")
comparison$modified
} # }