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How to randomly sample rows from an R data frame using sample_n?
To randomly sample rows from an R data frame using sample_n, we can directly pass the sample size inside sample_n function of dplyr package. For example, if we have data frame called df then to create a random sample of 5 rows in df can be done by using the command −
df%>%sample_n(5)
Example1
Consider the below data frame −
x1<-rnorm(20,21,3.24) x2<-rnorm(20,5,2.1) df1<-data.frame(x1,x2) df1
Output
x1 x2 1 21.17214 4.256648 2 24.41776 4.835844 3 22.57051 5.943711 4 18.80514 3.365967 5 21.49105 1.583063 6 20.04658 8.334448 7 16.03291 5.094798 8 21.71183 3.497276 9 18.27658 6.657804 10 15.75965 3.092517 11 24.15690 3.618473 12 25.91623 4.283104 13 24.65660 3.759834 14 18.80581 6.551064 15 25.15142 2.812932 16 20.48691 6.844323 17 25.56193 5.479819 18 22.22655 4.492731 19 20.56847 7.983841 20 23.24853 5.266284
Loading dplyr package and randomly sampling 10 rows in df1 −
library(dplyr) df1%>%sample_n(10)
x1 x2 1 18.80581 6.551064 2 25.91623 4.283104 3 16.03291 5.094798 4 15.75965 3.092517 5 18.27658 6.657804 6 18.80514 3.365967 7 22.57051 5.943711 8 20.04658 8.334448 9 24.41776 4.835844 10 24.15690 3.618473
Example2
y1<-sample(0:1,20,replace=TRUE) y2<-sample(LETTERS[1:5],20,replace=TRUE) df2<-data.frame(y1,y2) df2
Output
y1 y2 1 0 E 2 0 B 3 1 E 4 0 E 5 0 D 6 1 A 7 0 D 8 1 A 9 0 E 10 0 C 11 1 E 12 1 C 13 0 A 14 0 A 15 1 D 16 0 C 17 1 D 18 0 E 19 0 D 20 0 E
Randomly sampling 10 rows in df2 −
df2%>%sample_n(10)
y1 y2 1 0 E 2 0 C 3 1 E 4 1 A 5 0 A 6 1 E 7 0 D 8 0 D 9 0 D 10 0 B
Updated on: 06-Mar-2021
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