How do I create dummy variables in a dataframe from a vector of characters?

Question

I have a data frame where a variable is a list of other variables.

data <- data.frame(
  id = c(10, 20, 30, 40),
  x = c("a,b", "a,d", "b,c", "d,b")
)
data <- data %>% mutate(x = strsplit(x, ",", fixed = TRUE))

  id   x
1 10 a,b
2 20 a,d
3 30 b,c
4 40 d,b

I want an easy way to create dummy variables based off of whether the variable is in the list or not, and put those results inside the original data frame.

For example,

  id a b c d
1 10 1 1 0 0
2 20 1 0 0 1
3 30 0 1 1 0
4 40 0 1 0 1

This is very similar to the question here, but I can't find a way to get any suggested method to work with data frames. I've looked at the dummies package, qdapTools, fastDummies, but nothing seems to have what I'm looking for.

Thank you so much for any help!

Don't run the `strsplit` step. Run this directly on `data`. `result <- splitstackshape::cSplit_e(data, "x", type = 'character', fill = 0)` — Ronak Shah, Nov 26 '20 at 04:50

score 0 · Accepted Answer · answered Nov 26 '20 at 04:50

Does this work:

library(dplyr)
library(tidyr)
data %>% separate_rows(x, sep = ',') %>% mutate(val = 1) %>% 
+   pivot_wider(names_from = x, values_from = val, values_fill = list(val = 0)) %>% 
+   select(1,2,3,5,4)
# A tibble: 4 x 5
     id     a     b     c     d
  <dbl> <dbl> <dbl> <dbl> <dbl>
1    10     1     1     0     0
2    20     1     0     0     1
3    30     0     1     1     0
4    40     0     1     0     1

How do I create dummy variables in a dataframe from a vector of characters?

1 Answers1