Creating new columns using loop in R-CodePudding

Consider the following data named df:

id  v1  v2
1    3  3,4,5,3,4,5
2    2  4,5,4
3    5  5,5,5
4    3  3,3,4
5    4  4,4,6,7

Now, I want to create new data set with new columns using loop. The column names are derived from the last column (v2). That means it starts from v3 (the smallest value in v2) and ends at v7 (the largest value in v2). The value of each cell of newly created columns is the number of times that number is repeated in v2. My new data set looks like the following:

id  v1   v3   v4   v5   v6  v7
1    3    2    2    2    0   0
2    2    0    2    1    0   0
3    5    0    0    3    0   0
4    3    2    1    0    0   0
5    4    0    2    0    1   1

Any help is highly appreciated!

CodePudding user response：

Assuming the 'v2' column is character class, split the column by , and use qdapTools::mtabulate to get the frequencies

library(qdapTools)
df[paste0("v", 3:7)] <- mtabulate(strsplit(df$v2, ","))
df$v2 <- NULL

-output

> df
  id v1 v3 v4 v5 v6 v7
1  1  3  2  2  2  0  0
2  2  2  0  2  1  0  0
3  3  5  0  0  3  0  0
4  4  3  2  1  0  0  0
5  5  4  0  2  0  1  1

data

df <- structure(list(id = 1:5, v1 = c(3L, 2L, 5L, 3L, 4L), v2 = c("3,4,5,3,4,5", 
"4,5,4", "5,5,5", "3,3,4", "4,4,6,7")), class = "data.frame", 
row.names = c(NA, 
-5L))