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How to find the sum of a column values up to a value in another column in R?
To find the sum of a column values up to a particular value in another column, we can use cumsum function with sum function.
For example, if we have a data frame called df that contains two columns say x and y and we want to find the sum of x values until y is equal to 2 then we can use the following command −
sum(df$x[cumsum(df$y==2)==0])
Example 1
Following snippet creates a sample data frame −
x1<-rpois(20,5) x2<-rpois(20,2) df1<-data.frame(x1,x2) df1
Output
The following dataframe is created −
x1 x2 1 9 4 2 1 2 3 5 3 4 5 2 5 4 2 6 14 2 7 11 3 8 2 2 9 6 1 10 6 2 11 1 2 12 3 3 13 3 0 14 6 2 15 6 0 16 9 3 17 5 1 18 6 4 19 5 2 20 2 2
To find the sum of x1 until x2 reached 0, add the following code to the above snippet −
x1<-rpois(20,5) x2<-rpois(20,2) df1<-data.frame(x1,x2) sum(df1$x1[cumsum(df1$x2==0)==0])
Output
If you execute all the above given snippets as a single program, it generates the following output −
[1] 67
Example 2
Following snippet creates a sample data frame −
y1<-round(rnorm(20),1) y2<-round(rnorm(20),1) df2<-data.frame(y1,y2) df2
Output
The following dataframe is created −
y1 y2 1 2.4 -0.7 2 0.1 2.7 3 -0.7 0.0 4 1.6 -1.9 5 0.2 -1.0 6 0.2 1.7 7 0.7 0.7 8 -0.1 -0.3 9 -0.2 -0.2 10 -1.3 1.4 11 -2.5 -0.4 12 1.2 0.9 13 0.8 -0.4 14 0.8 -1.3 15 0.6 0.5 16 -0.8 -1.8 17 0.4 -0.4 18 0.4 0.6 19 -1.0 0.2 20 0.3 0.6
To find the sum of y1 until y2 reached 0.5, add the following code to the above snippet −
y1<-round(rnorm(20),1) y2<-round(rnorm(20),1) df2<-data.frame(y1,y2) sum(df2$y1[cumsum(df2$y2==0.5)==0])
Output
If you execute all the above given snippets as a single program, it generates the following output −
[1] 3.2
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