如何在 r 中使用 dplyr 将具有条件的多行折叠成一行？答案

【问题标题】：How to collapse multiple rows with condition into one row using dplyr in r?如何在 r 中使用 dplyr 将具有条件的多行折叠成一行？
【发布时间】：2021-11-25 08:03:10
【问题描述】：

我会用一个例子来说明我的问题。

样本数据：

df <- data.frame(ID = 1:5, Description = c("'foo' is a dog", "'bar' is a dog", "'foo' is a cat", "'foo' is not a cat", "'bar' is a fish"), Category = c("A", "A", "B", "B", "C"))

> df
 ID      Description Category
1  1     'foo' is a dog        A
2  2     'bar' is a dog        A
3  3     'foo' is a cat        B
4  4     'foo' is not a cat    B
5  5     'bar' is a fish       C

我想要做的是折叠相同类别的相似描述/ID，预期输出：

 ID  Description          Category
1 3     B        ‘foo’ is a cat    
2 1,2   A        ‘foo,bar’ is a dog
3 5     C        ‘bar’ is a fish   
4 4     B        ‘foo’ is not a cat

我想开始使用 dplyr，但我无法完全了解如何实现这一点，谁能帮助我？

df %>% 
  group_by(Category) %>% 
  ## some condition to check if content outside of single quote are the same. 
  ## If so, collapse them into one row, otherwise, leave as it is. 
  ## The regex to get the content outside of single quote 
     `gsub("^'(.*?)'.*", "\\2", x)` 
  ## then collapse 
  summarise(new description = paste())

【问题讨论】：

我会以这个为起点：df %>% group_by(Category) %>% summarize(Description = stringr::str_c(Description, collapse = ", "), ID = stringr::str_c(ID, collapse = ","))

标签： r dplyr tidyverse reshape

【解决方案1】：

这是实现输出的另一种方法。

library(tidyverse)

df %>%
  mutate(value = str_extract(Description, "'\\w+'"), 
         Description = trimws(str_remove(Description, value))) %>%
  group_by(Description, Category) %>%
  summarise(ID = toString(ID), 
            value = sprintf("'%s'", toString(gsub("'", "", value)))) %>%
  unite(Description, value, Description, sep = ' ')

#  Description         Category ID   
#  <chr>               <chr>    <chr>
#1 'foo' is a cat      B        3    
#2 'foo, bar' is a dog A        1, 2 
#3 'bar' is a fish     C        5    
#4 'foo' is not a cat  B        4

【讨论】：

【解决方案2】：

只要弄清楚，请随时提出更好的解决方案：

df %>% 
  mutate(sec = gsub("^'.*?'(.*)", "\\1", Description),
         content = gsub("^'(.*?)'.*", "\\1", Description)) %>% 
  group_by(sec, Category) %>%
  summarise(
    ID=str_c(unique(ID), collapse=","),
    content=str_c(unique(content), collapse=",")) %>%
  mutate(Description=str_c(sQuote(content), sec)) %>%
  ungroup() %>%
  dplyr::select(ID, Category, Description)

【讨论】：