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How to convert a data frame to data.table in R?
Since operations with data.table are sometimes faster than the data frames, we might want to convert a data frame to a data.table object. The main difference between data frame and data.table is that data frame is available in the base R but to use data.table we have to install the package data.table. We can do this with the help setDT function in the data.table package.
Example
Consider the below data frame −
> set.seed(1) > x1<-rnorm(20,0.5) > x2<-rnorm(20,0.8) > x3<-rpois(20,2) > x4<-rpois(20,5) > x5<-runif(20,5,10) > df<-data.frame(x1,x2,x3,x4,x5) > df x1 x2 x3 x4 x5 1 -0.1264538 1.7189774 2 6 9.959193 2 0.6836433 1.5821363 3 4 7.477968 3 -0.3356286 0.8745650 1 4 7.421748 4 2.0952808 -1.1893517 1 11 5.867212 5 0.8295078 1.4198257 3 6 8.774105 6 -0.3204684 0.7438713 1 3 7.269477 7 0.9874291 0.6442045 3 3 7.555849 8 1.2383247 -0.6707524 0 5 6.037726 9 1.0757814 0.3218499 1 8 6.143291 10 0.1946116 1.2179416 1 5 7.978560 11 2.0117812 2.1586796 1 10 7.874361 12 0.8898432 0.6972123 0 6 5.385322 13 -0.1212406 1.1876716 2 4 5.177703 14 -1.7146999 0.7461950 4 4 8.213977 15 1.6249309 -0.5770596 3 3 9.643076 16 0.4550664 0.3850054 3 1 7.990462 17 0.4838097 0.4057100 2 6 7.804504 18 1.4438362 0.7406866 2 2 7.630139 19 1.3212212 1.9000254 3 5 9.925476 20 1.0939013 1.5631757 2 6 7.538209
Loading data.table package −
> library(data.table)
Converting data frame df to data.table?
> setDT(df)
Checking whether df is a data.table or not −
> is.data.table(df) [1] TRUE
Let’s have a look at one more example −
> y1<-letters[1:20]
> y2<-rep(c("Group1","Group2","Group3","Group4"),times=5)
> y3<-1:20
> df_new<-data.frame(y1,y2,y3)
> df_new
y1 y2 y3
1 a Group1 1
2 b Group2 2
3 c Group3 3
4 d Group4 4
5 e Group1 5
6 f Group2 6
7 g Group3 7
8 h Group4 8
9 i Group1 9
10 j Group2 10
11 k Group3 11
12 l Group4 12
13 m Group1 13
14 n Group2 14
15 o Group3 15
16 p Group4 16
17 q Group1 17
18 r Group2 18
19 s Group3 19
20 t Group4 20
> setDT(df_new)
> is.data.table(df_new)
[1] TRUE
Updated on: 11-Aug-2020
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