CODEWITHSUNDEEP
rdataframelistdplyrmutate
Violin125
Violin125

Reputation: 133

How do I create a dataframe column that constitutes a list of multiple separate column entries?

I would like to create a fifth column in the below sample dataset that contains a list of columns 2:4 for each row. The desired output would be c(20,40,14) for the first row and c(13,13,0) for the second row.

My current attempt (shown in reproducible example below) yields the error "in mutate(): ℹ In argument: list_column = list(fastballs, sliders, curves). Caused by error: ! list_column must be size 2 or 1, not 3.

Any and all help appreciated.

library(tidyverse)

df <- data.frame(name = c('Bob','AJ'),
                fastballs = c(20,13),
                sliders = c(40,13),
                curves = c(14,0)) %>% 
mutate(list_column = list(fastballs,sliders,curves))

Upvotes: 3

Views: 74

Answers (3)

Jon Spring
Jon Spring

Reputation: 66880

Another option is tidyr::nest, which creates a list-column of data frames, which can be useful for some workflows but might not be what you want.

data.frame(name = c('Bob','AJ'),
                 fastballs = c(20,13),
                 sliders = c(40,13),
                 curves = c(14,0)) %>% 
  nest(list_column = -name)


df$list_column

#[[1]]
## A tibble: 1 × 3
#  fastballs sliders curves
#      <dbl>   <dbl>  <dbl>
#1        20      40     14
# 
#[[2]]
## A tibble: 1 × 3
#  fastballs sliders curves
#      <dbl>   <dbl>  <dbl>
#1        13      13      0

Upvotes: 3

lroha
lroha

Reputation: 34586

Two possible options:

library(purrr)
library(dplyr)

df |>
  mutate(list_column  = pmap(pick(fastballs:curves), c))

or:

df |>
  rowwise() |>
  mutate(list_column = list(c(c_across(fastballs:curves)))) |>
  ungroup()

Upvotes: 5

Ric
Ric

Reputation: 5721

What about using Map

library(dplyr)

df <- data.frame(name = c('Bob','AJ'),
                 fastballs = c(20,13),
                 sliders = c(40,13),
                 curves = c(14,0)) %>% 
  mutate(list_column = Map(f=list, fastballs,sliders,curves))

df

Upvotes: 1

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