I have a data frame with several binary variables: x1, x2, ... x100. I want to replace the entry 1 in each column with the number in the name of the column, i.e.:
data$x2[data$x2 == 1] <- 2
data$x3[data$x3 == 1] <- 3
data$x4[data$x4 == 1] <- 4
data$x5[data$x5 == 1] <- 5
...
How can I achieve this in a loop?
Using col:
# example data
set.seed(1); d <- as.data.frame(matrix(sample(0:1, 12, replace = TRUE), nrow = 3))
names(d) <- paste0("x", seq(ncol(d)))
d
# x1 x2 x3 x4
# 1 0 0 0 1
# 2 1 1 0 0
# 3 0 0 1 0
ix <- d == 1
d[ ix ] <- col(d)[ ix ]
d
# x1 x2 x3 x4
# 1 0 0 0 4
# 2 1 2 0 0
# 3 0 0 3 0
dplyr approach (using zx8754's data):
library(dplyr)
d %>%
mutate(across(starts_with('x'), ~ . * as.numeric(gsub('x', '', cur_column()))))
#> x1 x2 x3 x4
#> 1 0 0 0 4
#> 2 1 2 0 0
#> 3 0 0 3 0
Created on 2021-05-26 by the reprex package (v2.0.0)
Here is a base R solution with a lapply loop.
data[-1] <- lapply(names(data)[-1], function(k){
n <- as.integer(sub("[^[:digit:]]*", "", k))
data[data[[k]] == 1, k] <- n
data[[k]]
})
data
set.seed(2021)
data <- replicate(6, rbinom(10, 1, 0.5))
data <- as.data.frame(data)
names(data) <- paste0("x", 1:6)
A solution based on a simple for loop is below (otherwise similar to the accepted answer using lapply):
for (i in 2:100) {
k <- paste0('x', i)
data[data[[k]] == 1, k] <- i
}