Split column in R to several columns based on column value

Question

I want to introduce new cols in df based on one column's values.

category col needs to be split on ',' and each split substring needs to go to newly introduced appropriate col.

Minimal example:

df <- data.frame(category=c('1, 2', '1, 3','3', '2, 3'),
                 othercolumn= c("Grealish", "Saka", "Henry", 'Jesus'))

Required df:

finaldf <- data.frame(category=c('1, 2', '1, 3','3', '2, 3'),
                      category1=c('1', '1',NA, NA),
                      category2=c('2',NA,NA, '2'),
                      category3=c(NA,'3','3', '3'),
                 othercolumn= c("Grealish", "Saka", "Henry", 'Jesus'))

category1, category2, and category3 cols will take values based on the category column, otherwise NA.

Answer 1

In base R you can do:

Using strsplt to split the numbers and convert it to numeric

setName the return in lapply and cbind to data frame

nums <- strsplit(df$category, ",") |> 
  type.convert(as.is = T)

cbind(df[1], do.call(rbind, lapply(nums, \(x){
    sq <- seq(max(unlist(nums)))
    ifelse(sq %in% x , sq, NA ) |> 
      setNames(paste0("category", sq))
  })), df[-1])

  category category1 category2 category3 othercolumn
1     1, 2         1         2        NA    Grealish
2     1, 3         1        NA         3        Saka
3        3        NA        NA         3       Henry
4     2, 3        NA         2         3       Jesus