如何在mutate语句中对两列进行排序和粘贴? [英] How do you sort and paste two columns in a mutate statement?

问题描述

我正在寻找将两列排序并粘贴到新列中的方法.

I'm looking to sort and paste two columns into a new column.

test = data.frame('a'='jump','b'='jam') 
test %>% mutate(new=paste(sort(a,b)))

预期输出是具有三列的数据帧:

expected output is data frame with three columns:

'a'='jump','b'='jam','c'='jamjump'

推荐答案

您必须使用 rowwise 以逐行方式粘贴字符串.

You have to use rowwise to paste the string in a row-wise fashion.

library(dplyr)

test %>%
  rowwise() %>%
  mutate(c = paste0(sort(c(a, b)), collapse = ''))

#   a     b     c      
#  <chr> <chr> <chr>  
#1 jump  jam   jamjump
#2 b     a     ab     

在较大的数据集上，

rowwise 往往会比较慢，为避免使用它，可以在粘贴之前先使用 pmin / pmax 对字符串进行排序

rowwise tend to be slower on larger datasets, to avoid using it you can use pmin/pmax to sort the string first before pasting.

test %>% 
  mutate(col1 = pmin(a, b), col2 = pmax(a, b), 
         c = paste0(col1, col2)) %>%
  select(a, b, c)

数据

test = data.frame('a'=c('jump', 'b'),'b'=c('jam', 'a'))

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