CODEWITHSUNDEEP
rlistdataframe
Seydou GORO
Seydou GORO

Reputation: 1285

How to manipulate a list of dataframe

I have a list of dataframes

mydata1<-data.frame(ID=1:3,age=c(15,20,32),sex=c("M","F","M"))
mydata2<-data.frame(ID=11:14,age=c(35,22,14,45),sex=c("F","F","M","M"),Diagnosis=c("Pneumony","AIDS","Cancer","Asthma"))
mydata3<-data.frame(ID=21:22,age=c(24,22),sex=c("M","F"),Country=c("France","UK"))

LST<-list(mydata1=mydata1,mydata2=mydata2,mydata3=mydata3)

and I want to select certain columns (ID and ages in this case) from each of the dataframe and then stack them by rowbind() in order to have such a dataset. I want to do all the manipulations on the list directly.

  ID age
1  1  15
2  2  20
3  3  32
4 11  35
5 12  22
6 13  14
7 14  45
8 21  24
9 22  22

Upvotes: 0

Views: 105

Answers (2)

Ronak Shah
Ronak Shah

Reputation: 389265

Here is a base R option -

cols <- c('ID', 'age')
do.call(rbind, lapply(LST, `[`, cols))

Upvotes: 2

Waldi
Waldi

Reputation: 41260

You could use map_dfr from purrr:

library(dplyr)
library(purrr)


LST %>% map_dfr(~.x %>% select(ID,age))

  ID age
1  1  15
2  2  20
3  3  32
4 11  35
5 12  22
6 13  14
7 14  45
8 21  24
9 22  22

map_dfr directly binds rows for outputs of type data.frame.
The ~.x %>% select(ID,age) notation is a shorthand for function(df) df %>% select(ID,age)

Upvotes: 2

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