Columns to dummies in R, example provided

Question

I have a dataframe which looks like this

uid     language_name
1   333        English
2   333        French
3   333        Dutch   
4   654        Spanish 
5   546        English
6   546        French 
7   432        Afrikaans  
8   302        German
9   302        Dutch

And I want it looking like this:

uid     English              French               Dutch         ..........
1   333        1                   1                    1
2   654        0                   0                    0
3   546        1                   1                    0
4   432        0                   0                    0
5   302        0                   0                    1

So I want to change my language_name column into different dummy columns with the languages as their names. Is there a quick and easy way to do this?

I tried working with the 'dummies' package. But I wasn't able to keep the 'uid' variable in. Also 'model.matrix', same problem. (I'm not that good at R) — Nicolas Vermeulen, Jan 11 '16 at 08:42

Marta · Accepted Answer · 2016-01-11T08:56:08.380

1

Try with reshape2. Like here:

library("reshape2")

dcast(cbind(z, ile=1), 
      uid~language_name, value.var="ile", fill=0) -> t

colnames(t)[-1] <- paste("Language_", colnames(t)[-1], sep="")

edited Jan 11 '16 at 08:56

answered Jan 11 '16 at 08:44

Marta

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This works! Thanks a lot. Do you know how I could get 'Language' in front of every column name? – Nicolas Vermeulen Jan 11 '16 at 08:54
I've edited my answer to show you, how to change column names. – Marta Jan 11 '16 at 08:56

score 0 · Answer 2 · answered Jan 11 '16 at 08:50

0

Usually better way for such dummy coding is to use sparse matrices and Matrix::sparse.model.matrix :

Matrix::sparse.model.matrix(uid ~ -1 + ., data=your_data_frame)

answered Jan 11 '16 at 08:50

Dmitriy Selivanov

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Columns to dummies in R, example provided

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