fifelse: Fast ifelse

In data.table: Extension of `data.frame`

Fast ifelse

Description

fifelse is a faster and more robust replacement of ifelse. It is comparable to dplyr::if_else and hutils::if_else. It returns a value with the same length as test filled with corresponding values from yes, no or eventually na, depending on test. Supports bit64's integer64 and nanotime classes.

Usage

  fifelse(test, yes, no, na=NA)

Arguments

test	A logical vector.
yes, no	Values to return depending on TRUE/FALSE element of test. They must be the same type and be either length 1 or the same length of test.
na	Value to return if an element of test is NA. It must be the same type as yes and no and its length must be either 1 or the same length of test. Default value NA. NULL is treated as NA.

Details

In contrast to ifelse attributes are copied from the first non-NA argument to the output. This is useful when returning Date, factor or other classes.

Unlike ifelse, fifelse evaluates both yes and no arguments for type checking regardless of the result of test. This means that neither yes nor no should be recursive function calls. For recursion, use fcase instead.

Value

A vector of the same length as test and attributes as yes. Data values are taken from the values of yes and no, eventually na.

See Also

fcoalesce

fcase

Examples

x = c(1:4, 3:2, 1:4)
fifelse(x > 2L, x, x - 1L)

# unlike ifelse, fifelse preserves attributes, taken from the 'yes' argument
dates = as.Date(c("2011-01-01","2011-01-02","2011-01-03","2011-01-04","2011-01-05"))
ifelse(dates == "2011-01-01", dates - 1, dates)
fifelse(dates == "2011-01-01", dates - 1, dates)
yes = factor(c("a","b","c"))
no = yes[1L]
ifelse(c(TRUE,FALSE,TRUE), yes, no)
fifelse(c(TRUE,FALSE,TRUE), yes, no)

# Example of using the 'na' argument
fifelse(test = c(-5L:5L < 0L, NA), yes = 1L, no = 0L, na = 2L)

# Example showing both 'yes' and 'no' arguments are evaluated, unlike ifelse
fifelse(1 == 1, print("yes"), print("no"))
ifelse(1 == 1, print("yes"), print("no"))

data.table documentation built on Oct. 10, 2024, 5:07 p.m.