Everyday R code (13)

If the data set regular have 2 columns ‘ID’ and ‘Answer’, but the ‘ID’ is not unique. That means one ID can have 2 or more Answer. We want to put all the Answer for the same ID into one cell, kind of grouping them into one. aggregate is useful for this case.

 

regular

##It will show

## ID Answer

## 1   A

## 2   B

## 2   C

## 3   A

## 1   D

trial<-aggregate(ANSWER ~ COMM_ID, data = regular, paste, collapse = “,,,”)

trial

##It will show

## ID Answer

## 1  A,,,D

## 2  B,,,C

## 3  A