How to collapse data frame rows in R by summing using dplyr?

To collapse data frame rows by summing using dplyr package, we can use summarise_all function of dplyr package. For example, if we have a data frame called df that has a categorical column say Group and one numerical column then collapsing of rows by summing can be done by using the command −

df%>%group_by(Group)%>%summarise_all(funs(sum))

Consider the below data frame −

Example

 Live Demo

Group<-sample(LETTERS[1:6],25,replace=TRUE) Response<-rnorm(25,3,0.24) df1<-data.frame(Group,Response) df1

Output

  Group Response 1  F   2.920793 2  C   2.898450 3  C   3.347825 4  A   3.174100 5  B   3.089882 6  C   2.918084 7  D   3.274836 8  F   2.709450 9  F   3.349442 10 F   2.995712 11 C   3.081089 12 A   3.123781 13 C   2.947828 14 C   3.096281 15 E   2.990183 16 E   3.061462 17 C   3.279717 18 C   2.932549 19 F   2.772635 20 B   2.993549 21 F   2.956203 22 E   2.920117 23 F   3.244469 24 F   3.376968 25 B   3.072305

Loading dplyr package and summing the rows of df1 based on Group column −

Example

library(dplyr) df1%>%group_by(Group)%>%summarise_all(funs(sum)) # A tibble: 6 x 2

Output

Group Response <chr> <dbl> 1 A  6.30 2 B  9.16 3 C  24.5 4 D  3.27 5 E  8.97 6 F  24.3

Example

 Live Demo

Region<-sample(c("Asia","Oceania","Africa","America"),25,replace=TRUE) Y<-rpois(25,5) df2<-data.frame(Region,Y) df2

Output

   Region   Y 1  Asia     2 2  America  4 3  Africa   4 4  Oceania  5 5  America  6 6  Asia     5 7  Oceania  9 8  Asia     4 9  Asia     4 10 America  5 11 Oceania  2 12 Africa   6 13 Asia     4 14 Oceania  7 15 Africa   7 16 America  2 17 Asia     5 18 Africa   2 19 America  3 20 Oceania  3 21 Oceania  4 22 Africa   5 23 Africa   5 24 Africa   5 25 America  6

Summing the rows of df2 based on Region column −

Example

df2%>%group_by(Region)%>%summarise_all(funs(sum)) # A tibble: 4 x 2

Output

    Region Y  <chr>    <int> 1 Africa   34 2 America  26 3 Asia   24 4 Oceania  30