using the %in% operator on multiple columns-CodePudding

I have a set, W <- c("a","b","c") And a dataframe

df <- data.frame(col1 = c(1,2,3), col2 = c("a","b","c"), col3 =c("t","b","p"))

I want to run the %in% operator on multiple columns to return TRUE/FALSE for columns 2 and 3. I want column 1 to remain the same.

I know I can do

>df$col1 <- df$col1 %in% W

and

>df$col2 <- df$col2 %in% W

I'm unsure how I can do this in one line. I am also fairly new to R and programming in general.

CodePudding user response：

You could apply a function across both of the columns:

library(tidyverse)

W <- c("a","b","c")
df <- tibble(col1 = c(1,2,3), col2 = c("a","b","c"), col3 =c("t","b","p"))

df |>
  mutate(across(c(col2, col3), \(x) x %in% W))
#> # A tibble: 3 x 3
#>    col1 col2  col3 
#>   <dbl> <lgl> <lgl>
#> 1     1 TRUE  FALSE
#> 2     2 TRUE  TRUE 
#> 3     3 TRUE  FALSE

CodePudding user response：

You can try:

df[,2:3] <- apply(df[,2:3], 2, function(x) x %in% W)

#  col1 col2  col3
#1    1 TRUE FALSE
#2    2 TRUE  TRUE
#3    3 TRUE FALSE

The 2 in apply applies the function across columns (1 would apply across rows). The df[,2:3] identifies only the second and third columns (could also do df[,-1]).

CodePudding user response：

lapply is designed for such operations on data frames.

apply is actually designed for matrices, and works slow on data frames.

The %in% operator is actually the function `%in%`() (try help(`%in%`)), so we may use it's name in the lapply and don't need an anonymous function (those with function(x) ...).

df[2:3] <- lapply(df[2:3], `%in%`, W)
df
#   col1 col2  col3
# 1    1 TRUE FALSE
# 2    2 TRUE  TRUE
# 3    3 TRUE FALSE

CodePudding user response：

Here is a variation of the given solutions:

library(dplyr)
df %>% 
  mutate(across(-col1, ~. %in% W))

  col1 col2  col3
1    1 TRUE FALSE
2    2 TRUE  TRUE
3    3 TRUE FALSE

CodePudding user response：

Try as.matrix

> df[-1] <- as.matrix(df[-1]) %in% W

> df
  col1 col2  col3
1    1 TRUE FALSE
2    2 TRUE  TRUE
3    3 TRUE FALSE