根据 cumsum 索引重复数据帧行

Question

我有一个数据框如下：

data.frame(title="Title", bk=c("Book 1", "Book 1", "Book 3"), ch=c("Chapter 1", "Chapter 2", "Chapter 1"))

  title     bk        ch
1 Title Book 1 Chapter 1
2 Title Book 1 Chapter 2
3 Title Book 3 Chapter 1

我如何根据下面的 cumsum 指数重复每个观察：

id=c(1,1,1,2,2,3,3,3,3)

以便可以扩展数据框以容纳生成 cumsum 索引的源向量？

  title     bk        ch   source_vector
1 Title Book 1 Chapter 1   ...
1 Title Book 1 Chapter 1   
1 Title Book 1 Chapter 1   
2 Title Book 1 Chapter 2   
2 Title Book 1 Chapter 2   
3 Title Book 3 Chapter 1   
3 Title Book 3 Chapter 1   
3 Title Book 3 Chapter 1   
3 Title Book 3 Chapter 1

Answer 1

一个选项是使用 separate_rows

library(tidyverse)
df1 %>%
    separate_rows(content)
#  title     bk        ch content
#1 Title Book 1 Chapter 1    This
#2 Title Book 1 Chapter 1      is
#3 Title Book 1 Chapter 1     the
#4 Title Book 1 Chapter 2 content
#5 Title Book 1 Chapter 2      of
#6 Title Book 3 Chapter 1    each
#7 Title Book 3 Chapter 1 chapter
#8 Title Book 3 Chapter 1      in
#9 Title Book 3 Chapter 1   books

如果我们需要复制原始行

df1 %>% 
    uncount(str_count(content, "\w+")) %>%
    as_tibble
# A tibble: 9 x 4
#  title bk     ch        content              
#  <fct> <fct>  <fct>     <fct>                
#1 Title Book 1 Chapter 1 This is the          
#2 Title Book 1 Chapter 1 This is the          
#3 Title Book 1 Chapter 1 This is the          
#4 Title Book 1 Chapter 2 content of           
#5 Title Book 1 Chapter 2 content of           
#6 Title Book 3 Chapter 1 each chapter in books
#7 Title Book 3 Chapter 1 each chapter in books
#8 Title Book 3 Chapter 1 each chapter in books
#9 Title Book 3 Chapter 1 each chapter in books

Answer 2

在 base 中你可以使用 do.call of r.bind，在你完成每一行的 strsplit 和 cbind 之后喜欢：

x <- data.frame(title="Title", bk=c("Book 1", "Book 1", "Book 3"), ch=c("Chapter 1", "Chapter 2", "Chapter 1"), content=c("This is the", "content of", "each chapter in books"))
do.call("rbind", by(x, 1:nrow(x), function(x) {cbind(x[-ncol(x)], str_split_content=strsplit(as.character(x$content[1]), " ")[[1]])}))
#    title     bk        ch str_split_content
#1.1 Title Book 1 Chapter 1              This
#1.2 Title Book 1 Chapter 1                is
#1.3 Title Book 1 Chapter 1               the
#2.1 Title Book 1 Chapter 2           content
#2.2 Title Book 1 Chapter 2                of
#3.1 Title Book 3 Chapter 1              each
#3.2 Title Book 3 Chapter 1           chapter
#3.3 Title Book 3 Chapter 1                in
#3.4 Title Book 3 Chapter 1             books

Answer 3

如果您只想根据 content 中的字数扩展行，那么这里有一种方法，

library(splitstackshape)
expandRows(ddf, lengths(gregexpr("\W+", ddf$content)) + 1, count.is.col = FALSE)

#    title     bk        ch               content
#1   Title Book 1 Chapter 1           This is the
#1.1 Title Book 1 Chapter 1           This is the
#1.2 Title Book 1 Chapter 1           This is the
#2   Title Book 1 Chapter 2            content of
#2.1 Title Book 1 Chapter 2            content of
#3   Title Book 3 Chapter 1 each chapter in books
#3.1 Title Book 3 Chapter 1 each chapter in books
#3.2 Title Book 3 Chapter 1 each chapter in books
#3.3 Title Book 3 Chapter 1 each chapter in books

Answer 4

这更接近我要找的东西：

df %>%
  mutate(str_split_content = str_split(content, " ")) %>%
  unnest()

有人发帖，然后 revised/removed 不久前。

原来的str_split内容实际上是标点符号。所以不完全是纯粹按字数拆分。

根据 cumsum 索引重复数据帧行

Repeat dataframe rows based on cumsum index

r

cumsum