Assignment (in-place modifier) operators

Modify the stored value of the left-hand-side object in place. These are the equivalent of operators such as +=, -=, *=, and /= in languages like C++ or 'Python'. %+=% and %-=% also work with strings, and %-=% accepts regular expressions.

Usage

x %+=% y

x %-=% y

x %*=% y

x %/=% y

x %^=% y

x %log=% y

x %root=% y

Arguments

x

a stored value

y

value to modify the stored value by

Value

Used for the side effect of reassigning x in the calling environment; returns the new value of x invisibly.

Author

Ben Wiseman, benjamin.h.wiseman@gmail.com

Examples

x <- 1
x %+=% 2
x == 3 # TRUE
#> [1] TRUE

x %-=% 3
x == 0 # TRUE
#> [1] TRUE

# Or with data frames...
test <- iris

# Simply modify in place
test$Sepal.Length[test$Species == 'setosa' & test$Petal.Length < 1.5] %+=% 1

# Which is much nicer than typing:
test$Sepal.Length[test$Species == 'setosa' & test$Petal.Length < 1.5] <-
test$Sepal.Length[test$Species == 'setosa' & test$Petal.Length < 1.5] + 1
# ...which is over the 100 character limit for R documentation!

# %+=% and %-=% also work with strings
x <- "ab"
x %+=% "c"
x %-=% "b"
x == "ac" # TRUE
#> [1] TRUE

# %-=% can also take regular expressions
x <- "foobar"
x %-=% "[fb]"
print(x)
#> [1] "ooar"
# "ooar"