split comma separated values to columns in r

Question

here's a sample of my data:

> a
   sample(dt$r, 10)
1                                  5
2                              2,5,6
3                                  5
4                               <NA>
5                               <NA>
6                                  5
7                                2,6
8                                  5
9                               <NA>
10                              <NA>

I want to seperate these values that convert them into columns. The dataframeshould look like this:

                                       2      5    6
    1                              FALSE    TRUE  FALSE
    2                              TRUE     TRUE  FALSE
    3                              FALSE    FALSE FALSE 
    4                              FALSE    FALSE FALSE 
    5                              FALSE    FALSE FALSE 
    6                              FALSE    TRUE  FALSE 
    7                              TRUE     FALSE TRUE
    8                              FALSE    TRUE  FALSE 
    9                              FALSE    FALSE FALSE 
    10                             FALSE    FALSE FALSE 

I'm trying to use tidyr::spread or strsplit but can't seem to find how

Answer 1

If you have to generalize, it's not the best answer.

Data

data <- data.frame(aux = c("5","2,5,6","5",NA,NA,"2,6"))

Code

library(dplyr)
library(stringr)

data %>%
  mutate(
    `2` = if_else(str_detect(aux,"2"),TRUE,FALSE),
    `5` = if_else(str_detect(aux,"5"),TRUE,FALSE),
    `6` = if_else(str_detect(aux,"6"),TRUE,FALSE)
  ) %>% 
  replace_na(list(`2` = FALSE,`5` = FALSE,`6` = FALSE))

Output

    aux     2     5     6
1     5 FALSE  TRUE FALSE
2 2,5,6  TRUE  TRUE  TRUE
3     5 FALSE  TRUE FALSE
4  <NA> FALSE FALSE FALSE
5  <NA> FALSE FALSE FALSE
6   2,6  TRUE FALSE  TRUE

Answer 2

Using strsplit this is one approach.

First get the data frame as a strsplit list, then get the values without <NA> , finally look for matches with sapply .

df_split <- strsplit(df$r, ",")

df_split_val <- sort(unique(unlist(df_split)))[2:4]

setNames(data.frame(t(sapply(df_split, function(x) 
  df_split_val %in% x))), df_split_val)
       2     5     6
1  FALSE  TRUE FALSE
2   TRUE  TRUE  TRUE
3  FALSE  TRUE FALSE
4  FALSE FALSE FALSE
5  FALSE FALSE FALSE
6  FALSE  TRUE FALSE
7   TRUE FALSE  TRUE
8  FALSE  TRUE FALSE
9  FALSE FALSE FALSE
10 FALSE FALSE FALSE

Data

df <- structure(list(r = c("5", "2,5,6", "5", "<NA>", "<NA>", "5",
"2,6", "5", "<NA>", "<NA>")), class = "data.frame", row.names = c(NA,
-10L))

Answer 3

A more general solution:

1. Identify all unique items present in your column

dt <- data.frame(r = c("5","2,5,6","5",NA,NA,"2,6"))
items <- sort(unique(unlist(strsplit(unique(dt$r), ","))))
items
[1] "2" "5" "6"

2. Create columns for each unique item by finding in-string matches using grepl

dt2 <- as.data.frame(sapply(items, function(item) grepl(item, dt$r, fixed=TRUE)))
dt2
      2     5     6
1 FALSE  TRUE FALSE
2  TRUE  TRUE  TRUE
3 FALSE  TRUE FALSE
4 FALSE FALSE FALSE
5 FALSE FALSE FALSE
6  TRUE FALSE  TRUE