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Merge lists

Source: R/merge-list.R
merge_list.Rd

Merge lists with different or intersecting names

Usage

merge_list(x, y, keep = c("x", "y"), null = c("ignore", "drop", "keep")[1:2])

Arguments

x, y

Lists to merge

keep

When matching names are found, from which object should the values be retained; "x" retains values from x, "y" retains values from y.

null

Method for handling NULL values. When two values are passed, they will be applied to x and y respectively. When a single value is passed, it will be applied to both x and y.

  • "ignore": NULL values are ignored. When passes to x, the NULL values will be retained if they are not overridden by y.

  • "drop": NULL values are dropped from merge and will not appear in the output.

  • "keep": NULL values are retained in the output and can override other values.

Examples

x <- list(a = 1, b = 2,    c = NULL, d = NULL)
y <- list(a = 2, b = NULL, c = 3)

# compared to:
utils::modifyList(x, y)
#> $a
#> [1] 2
#> 
#> $c
#> [1] 3
#> 
#> $d
#> NULL
#> 
utils::modifyList(x, y, keep.null = TRUE)
#> $a
#> [1] 2
#> 
#> $b
#> NULL
#> 
#> $c
#> [1] 3
#> 
#> $d
#> NULL
#> 

merge_list(x, y)
#> $a
#> [1] 1
#> 
#> $b
#> [1] 2
#> 
#> $c
#> [1] 3
#> 
#> $d
#> NULL
#> 
merge_list(x, y, keep = "y")
#> $a
#> [1] 2
#> 
#> $b
#> [1] 2
#> 
#> $c
#> [1] 3
#> 
#> $d
#> NULL
#> 
merge_list(x, y, null = "drop")
#> $a
#> [1] 1
#> 
#> $b
#> [1] 2
#> 
#> $c
#> [1] 3
#>