在特定位置组合两个不同长度的数据帧

Question

我有两个数据框，一个有 7 行，另一个有 2 行。这是两个框架：

                content ChatPosition
1  This is a start line        START
2 This is a middle line       MIDDLE
3 This is a middle line       MIDDLE
4 This is the last line          END
5  This is a start line        START
6 This is a middle line       MIDDLE
7 This is the last line          END

和

  rating text_type
1 0.2324   Postive
2 0.8999   Postive

基本上我想合并两个数据框，但我想合并它们，以便 rating 和 text_type 数据框中的值与第一个数据框的第 1 行和第 5 行中的值对齐。换句话说，来自 df2 的值只能插入到 ChatPosition 值 = "START" 的位置，所以我希望得到一个如下所示的数据框：

                content ChatPosition rating text_type
1  This is a start line        START 0.2324   Postive
2 This is a middle line       MIDDLE     NA      <NA>
3 This is a middle line       MIDDLE     NA      <NA>
4 This is the last line          END     NA      <NA>
5  This is a start line        START 0.8999   Postive
6 This is a middle line       MIDDLE     NA      <NA>
7 This is the last line          END     NA      <NA>

我查看了 stackexchange，似乎有许多与解决类似问题相关的问题和答案，其中 OP 没有为要合并的两个帧指定特定的匹配标准。这里有一些有用的代码，但我无法扩展它来解决我的问题：

combining two data frames of different lengths.

我在下面添加了代码来填充两个数据框。如果有人可以提供帮助，将不胜感激。

content <- c("This is a start line" , "This is a middle line" , "This is a middle line" ,"This is the last line" ,
         "This is a start line" , "This is a middle line" , "This is the last line")
ChatPosition <- c("START" , "MIDDLE" , "MIDDLE" , "END" , "START" ,"MIDDLE" , "END")


df <- data.frame(content, ChatPosition)
df

rating <- c(0.2324, 0.8999)
text_type <- c("Postive", "Postive")
df2 <- data.frame(rating, text_type)
df2

Answer 1

例如

row.names(df2) <- c(1,5)
merge(df, df2, by="row.names", all.x=TRUE)[,-1]
#                 content ChatPosition rating text_type
# 1  This is a start line        START 0.2324   Postive
# 2 This is a middle line       MIDDLE     NA      <NA>
# 3 This is a middle line       MIDDLE     NA      <NA>
# 4 This is the last line          END     NA      <NA>
# 5  This is a start line        START 0.8999   Postive
# 6 This is a middle line       MIDDLE     NA      <NA>
# 7 This is the last line          END     NA      <NA>

Answer 2

我认为你可以通过创建空列然后有条件地填充它们来最容易地做到这一点

df3<- df
df3
df3$rating<- NA
df3$text_type<- NA

df3$rating[df3$ChatPosition=="START"]<- df2$rating
df3$text_type[df3$ChatPosition=="START"]<- as.character(df2$text_type)

df3

编辑：在此我假设您想在标记为START的行中插入评分