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

Question

Essentially, I am taking a list of emotions and trying to replicate each emotion on the list 6 times and then add them to a vector. For example:

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

will look like:

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

Right now to do this, I am using a for loop but for some reason it's only replicating the first emotion, creating the vector, emotions2<-c("Happy","Happy","Happy","Happy","Happy","Happy").

My code looks like this: pmd.df3 is my data frame and Emotions is the new column in it where I'll store this info.

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

Please let me know if you can help!

Please include on your question what programming language you are using. — Ricardo Paixao, Jun 27 '17 at 21:20
Suggestion : Mention the programming language your code is in. It will help you get the solution faster as right developers will be able to see your code. Always tag your questions with right kind of tags. — Chandan Purbia, Jun 27 '17 at 21:24

score 0 · Accepted Answer · answered Jun 27 '17 at 21:26

0

To achieve that, you can use lapply (to apply a function to each element of a list/vector) and unlist (to flatten the resulting list of lists):

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

Full example:

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

answered Jun 27 '17 at 21:26

Aurélien Gasser

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Can you tell me why my code did NOT work? It was working when I said "print" but as soon as I saved it as a vector it deleted all emotions but for the first one (which it did replicate 6 times). – Andrew Colin Jun 27 '17 at 21:38
@AndrewColin I'm not too familiar with using `print` in the code like you did, but I *think* what was going on is you didn't aggregate all the emotions in a single vector (`pmd.df3$Emotions <-` is expecting a single vector, not several). Also, if my answer is the correct one, feel free to mark it as accepted ;) – Aurélien Gasser Jun 27 '17 at 21:42
That logic makes sense to me. Thanks for the answer and explanation! – Andrew Colin Jun 28 '17 at 12:04

score 0 · Answer 2 · answered Jun 27 '17 at 21:44

To piggyback off of shambalambala's answer, rep can handle this natively without needing lapply or a for loop.

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

This worked as well. Thank you for sharing this option too! – Andrew Colin Jun 28 '17 at 12:04 — Andrew Colin, Jun 28 '17 at 12:04

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

2 Answers2