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How to find the difference between row values starting from bottom of an R data frame?
If an R data frame contains all numerical columns and we want to find the difference between row values then we will lose first row of the data frame because that will not be subtracted from any row. This can be done by using head function and minus sign. It will work as subtracting the second last row from the last row, then subtracting third last row from the second last row and so on.
Example
Consider the below data frame −
x1<-rpois(20,2) y1<-rpois(20,3) z1<-rpois(20,5) w1<-rpois(20,8) v1<-rpois(20,10) df1<-data.frame(x1,y1,z1,w1,v1) df1
Output
x1 y1 z1 w1 v1 1 2 3 3 13 15 2 4 1 8 12 7 3 1 1 5 8 8 4 2 2 5 6 11 5 4 4 5 7 8 6 4 9 4 8 6 7 1 2 4 10 12 8 1 3 4 10 9 9 2 2 3 7 6 10 2 5 6 8 10 11 1 2 3 4 8 12 0 2 4 12 11 13 3 5 5 7 5 14 1 2 3 4 7 15 1 3 6 6 9 16 3 6 4 12 10 17 3 1 3 14 17 18 4 4 4 7 11 19 2 3 7 6 14 20 3 4 4 9 15
Finding the difference between starting from bottom −
Example
tail(df1,-1)-head(df1,-1)
Output
x1 y1 z1 w1 v1 2 2 -2 5 -1 -8 3 -3 0 -3 -4 1 4 1 1 0 -2 3 5 2 2 0 1 -3 6 0 5 -1 1 -2 7 -3 -7 0 2 6 8 0 1 0 0 -3 9 1 -1 -1 -3 -3 10 0 3 3 1 4 11 -1 -3 -3 -4 -2 12 -1 0 1 8 3 13 3 3 1 -5 -6 14 -2 -3 -2 -3 2 15 0 1 3 2 2 16 2 3 -2 6 1 17 0 -5 -1 2 7 18 1 3 1 -7 -6 19 -2 -1 3 -1 3 20 1 1 -3 3 1
Let’s have a look at another example −
Example
x2<-sample(1:10,20,replace=TRUE) y2<-sample(1:10,20,replace=TRUE) z2<-sample(1:10,20,replace=TRUE) w2<-sample(1:10,20,replace=TRUE) v2<-sample(1:10,20,replace=TRUE) df2<-data.frame(x2,y2,z2,w2,v2) df2
Output
x2 y2 z2 w2 v2 1 10 6 2 8 8 2 8 7 1 6 10 3 6 5 10 2 8 4 3 5 4 4 4 5 10 6 3 1 3 6 5 6 6 7 1 7 4 7 5 9 4 8 2 6 2 1 1 9 2 7 5 4 4 10 2 2 6 6 9 11 2 2 4 8 3 12 2 10 1 5 2 13 8 3 8 8 10 14 8 9 3 10 3 15 7 5 10 2 1 16 2 8 4 7 5 17 4 3 7 4 2 18 5 8 3 8 2 19 5 9 5 4 2 20 6 5 6 7 9
Example
tail(df2,-1)-head(df2,-1)
Output
x2 y2 z2 w2 v2 2 -2 1 -1 -2 2 3 -2 -2 9 -4 -2 4 -3 0 -6 2 -4 5 7 1 -1 -3 -1 6 -5 0 3 6 -2 7 -1 1 -1 2 3 8 -2 -1 -3 -8 -3 9 0 1 3 3 3 10 0 -5 1 2 5 11 0 0 -2 2 -6 12 0 8 -3 -3 -1 13 6 -7 7 3 8 14 0 6 -5 2 -7 15 -1 -4 7 -8 -2 16 -5 3 -6 5 4 17 2 -5 3 -3 -3 18 1 5 -4 4 0 19 0 1 2 -4 0 20 1 -4 1 3 7
Updated on: 08-Sep-2020
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