[R] aggregate counting variable factors

Kai Mx
Wed, 16 Sep 2015 20:43:16 -0000

Hi everybody,

>From a questionnaire, I have a dataset  like this one with some 40 items:

df1 <- data.frame(subject=c('user1','user2', 'user3',
'user4'),
item1=c(0,1,2,5), item2=c(1,2,1,2), item3=c(2,3,4,0), item4=c(0,3,3,2),
item5=c(5,5,5,5))

Users can choose an answer from 0 to 5 for each item.

Now I want to reshape the dataset to have the items in rows and the count
of each of the result factors in columns:

result <- data.frame (item=c("item1", "item2",
"item3", "item4", "item5"),
result0=c(1,0,1,1,0), result1=c(1,2,0,0,0), result2=c(1,2,1,1,0),
result3=c(0,0,1,2,0), result4=c(0,0,1,0,0), result5=c(1,0,0,0,4))

I have been fiddling around with melt/plyr, but haven't been able to figure
it out. What's the most elegant way to do this (preferably without typing
in all the item names).

Thanks so much!

Best,

Kai

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