为什么我的 for 循环不遍历整个列表？

Question

本质上，我正在制作一个情绪列表，并尝试将列表中的每种情绪复制 6 次，然后将它们添加到一个向量中。例如：

emotions<-c("Happy","Sad","Angry")

看起来像：

emotions2<-c("Happy","Happy","Happy","Happy","Happy","Happy","Sad","Sad","Sad","Sad","Sad","Angry","Angry","Angry","Angry","Angry","Angry")

现在要做到这一点，我正在使用 for 循环，但出于某种原因，它只是复制了第一种情绪，创建了向量， emotions2<-c("Happy","Happy","Happy","Happy","Happy","Happy").

我的代码如下所示： pmd.df3 是我的数据框，Emotions 是其中的新列，我将在其中存储此信息。

  pmd.df3$Emotions<-(
     for(ele in emotions){
       new.column<-replicate(6,ele)
       print(new.column)
     }
   )

如果你能帮上忙，请告诉我！

Answer 1

为此，您可以使用 lapply（将函数应用于 list/vector 的每个元素）和 unlist（展平列表的结果列表）：

pmd.df3$Emotions <- unlist(lapply(emotions, function(x) { rep(x, 6) }))

完整示例：

emotions <- c("Happy", "Sad", "Angry")
pmd.df3 = data.frame(id = seq(1, 18))

pmd.df3$Emotions <- unlist(lapply(emotions, function(x) { rep(x, 6) }))
pmd.df3 
#    id Emotions
# 1   1    Happy
# 2   2    Happy
# 3   3    Happy
# 4   4    Happy
# 5   5    Happy
# 6   6    Happy
# 7   7      Sad
# 8   8      Sad
# 9   9      Sad
# 10 10      Sad
# 11 11      Sad
# 12 12      Sad
# 13 13    Angry
# 14 14    Angry
# 15 15    Angry
# 16 16    Angry
# 17 17    Angry
# 18 18    Angry

Answer 2

借助 shambalambala 的回答，rep 可以在本机处理此问题，而无需 lapply 或 for 循环。

emotions <- c("Happy", "Sad", "Angry")
pmd.df3 = data.frame(id = seq(1, 18))
pmd.df3$Emotions <- rep(emotions, each = 6)

   id Emotions
1   1    Happy
2   2    Happy
3   3    Happy
4   4    Happy
5   5    Happy
6   6    Happy
7   7      Sad
8   8      Sad
9   9      Sad
10 10      Sad
11 11      Sad
12 12      Sad
13 13    Angry
14 14    Angry
15 15    Angry
16 16    Angry
17 17    Angry
18 18    Angry

为什么我的 for 循环不遍历整个列表？

Why won't my for loop iterate over the whole list?

loops

for-loop

r

replicate