CODEWITHSUNDEEP
rdataframe
Carbo
Carbo

Reputation: 916

report the value of a numbered column depending on the number specified in another column in R

What I have:

data

 0_x  1_x  2_x ...10_x num_col 
 0.2  0.3  0.4          2
 0.3. 0.5  0.3          1
 0    0.2  0.8          3

what I want:

      0_x  1_x  2_x ...10_x num_col value
      0.2  0.3  0.4      .   2       0.3
      0.3. 0.5  0.3      .   1       0.3
      0    0.2  0.8      .   3       0.8

basically I want to create a column with the value corresponding to the column indicated by "num_col"

Upvotes: 1

Views: 31

Answers (1)

tmfmnk
tmfmnk

Reputation: 39858

One option involving dplyr could be:

df %>% 
 rowwise() %>% 
 mutate(value = get(paste0(num_col-1, "_x"))) %>%
 ungroup()

  `0_x` `1_x` `2_x` num_col value
  <dbl> <dbl> <dbl>   <int> <dbl>
1   0.2   0.3   0.4       2   0.3
2   0.3   0.5   0.3       1   0.3
3   0     0.2   0.8       3   0.8

It does, however, assume that your columns are named in a certain way.

Sample data:

df <- structure(list(`0_x` = c(0.2, 0.3, 0), `1_x` = c(0.3, 0.5, 0.2
), `2_x` = c(0.4, 0.3, 0.8), num_col = c(2L, 1L, 3L)), class = "data.frame", row.names = c(NA, 
                                                                                           -3L))

Upvotes: 1

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