有条件地连接多行字符串

Question

我从包含多行字符串的 PDF 中提取了多个表格。我使用了 tabulizer 包中的 extract_table() 函数，唯一的问题是字符串作为单独的行导入。

例如

action <- c(1, NA, NA, 2, NA, 3, NA, NA, NA, 4, NA)

description <- c("a", "b", "c", "a", "b", "a", "b", "c", "d", "a", "b")

data.frame(action, description)

       action description
1       1           a
2      NA           b
3      NA           c
4       2           a
5      NA           b
6       3           a
7      NA           b
8      NA           c
9      NA           d
10      4           a
11     NA           b

我想连接字符串，使它们显示为相同的元素，例如：

  action description
1      1       a b c
2      2         a b
3      3     a b c d
4      4         a b

希望有道理，感谢任何帮助！

Answer 1

您可以像这样使用 zoo 和 dplyr 包

library(zoo)
library(dplyr)
action <- c(1, NA, NA, 2, NA, 3, NA, NA, NA, 4, NA)
description <- c("a", "b", "c", "a", "b", "a", "b", "c", "d", "a", "b")
df = data.frame(action, description)
df$action = na.locf(df$action)
df = 
    df %>% 
    group_by(action) %>% 
    summarise(description = paste(description, collapse = ' '))

Answer 2

tidyverse 方法是 fill action 具有先前非 NA 值的列然后 group_by Action 和 paste description在一起。

library(tidyverse)

df %>%
 fill(action) %>%
 group_by(action) %>%
 summarise(description = paste(description, collapse = " "))


#  action description
#   <dbl> <chr>      
#1     1. a b c      
#2     2. a b        
#3     3. a b c d    
#4     4. a b

Answer 3

一个base R选项

dat <- data.frame(action, description)
aggregate(
  description ~ action,
  transform(dat, action = cumsum(!is.na(dat$action))),
  FUN = paste,
  ... = collapse = " "
)
#  action description
#1      1       a b c
#2      2         a b
#3      3     a b c d
#4      4         a b

要使 aggregate 正常工作，我们需要将 action 更改为 cumsum(!is.na(dat$action))) 返回的内容，即

cumsum(!is.na(dat$action)))
#[1] 1 1 1 2 2 3 3 3 3 4 4

Answer 4

这里有一个选项 data.table

library(data.table)
setDT(df1)[, .(description = paste(description, collapse = ' ')), 
                  .(action = cumsum(!is.na(action)))]
#   action description
#1:      1       a b c
#2:      2         a b
#3:      3     a b c d
#4:      4         a b

或使用 zoo

中的 na.locf

library(zoo)
setDT(df1)[, .(description = paste(description, collapse = ' ')),
              .(action = na.locf(action))]

数据

df1 <- data.frame(action, description)

有条件地连接多行字符串

Conditionally concatenate string over multiple rows

string

r

string-concatenation

数据