Question

I have a data with the format as data_format1. Based on it, I want to convert the cases to variables to get data_format2.

you can find data_format1 here:

ArticleID<-c(1, 2, 3, 3, 4)
Word<-c("a", "b", "b", "c", "c")
Freq<-c(2, 4, 6, 3, 2)
data_format1<-cbind(ArticleID, Word, Freq)

data_format1

     ArticleID Word Freq
[1,] "1"       "a"  "2" 
[2,] "2"       "b"  "4" 
[3,] "3"       "b"  "6" 
[4,] "3"       "c"  "3" 
[5,] "4"       "c"  "2" 

data_format2 is given here:

ArticleID_t<-c(1, 2, 3, 4)
a<-c(2, 0, 0, 0)
b<-c(0, 4, 6, 0)
c<-c(0, 0, 3, 2)
data_format2<-cbind(ArticleID_t, a, b, c)
data_format2

     ArticleID_t a b c
[1,]           1 2 0 0
[2,]           2 0 4 0
[3,]           3 0 6 3
[4,]           4 0 0 2

Answer 1

This is a classical reshape problem – converting data from a tall format to a wide format. The reshape2 package is ideal for this.

Note: You need to convert your data into a data.frame first. Remember that cbind will take your data and create an array, rather than a data.frame. So in the solution I use data.frame(...) to recreate your data.

library(reshape2)
data_format1 <- data.frame(ArticleID, Word, Freq)
reshape2::dcast(data_format1, ArticleID~Word, sum)

  ArticleID a b c
1         1 2 0 0
2         2 0 4 0
3         3 0 6 3
4         4 0 0 2

See ?reshape2::dcast for more information.