如何合并一列中的行以匹配另一列中的非空行？答案

【问题标题】：How to merge rows in one column to match non-empty rows in the other column?如何合并一列中的行以匹配另一列中的非空行？
【发布时间】：2017-11-25 11:41:46
【问题描述】：

我有一个包含两列的 .csv 文件。第一个是 ID，第二个是文本字段。但是，文本字段中的文本被拆分为延伸到另一行的句子，因此文件如下所示：

ID TEXT
TXT_1 This is the first sentence
NA This is the second sentence
NA This is the third sentence
TXT_2 This is the first sentence of the second text
NA This is the second sentence of the second text

我想做的是合并文本字段，使其看起来像这样：

ID TEXT
TXT_1 This is the first sentence This is the second sentence This is the third sentence
TXT_2 This is the first sentence of the second text This is the second sentence of the second text

在 R 中有一个简单的解决方案吗？

【问题讨论】：

标签： r csv text

【解决方案1】：

我们根据“ID”和paste“TEXT”中的非NA元素一起创建分组变量

library(dplyr)
df1 %>% 
    group_by(Grp = cumsum(!is.na(ID))) %>% 
    summarise(ID = ID[!is.na(ID)], TEXT = paste(TEXT, collapse = ' ')) %>%
    ungroup() %>%
    select(-Grp)  
# A tibble: 2 x 2
#     ID                                                                                         TEXT
#    <chr>                                                                                        <chr>
#1 TXT_1            This is the first sentence This is the second sentence This is the third sentence
#2 TXT_2 This is the first sentence of the second text This is the second sentence of the second text

或者按照@Jaap 的建议

df1 %>% 
   group_by(ID = zoo::na.locf(ID)) %>%
   summarise(TEXT = paste(TEXT, collapse = ' '))

【讨论】：

或：df1 %>% group_by(ID = zoo::na.locf(ID)) %>% summarise(TEXT = paste(TEXT, collapse = ' '))