Home/ Questions/Q 9225143
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-06-18T04:30:21+00:00

I have a sample dataframe sample.data as follows: x y z 1 0 1

  • 0

I have a sample dataframe sample.data as follows: 

x   y   z
1   0   1
1   0   1
1   0   1
1   0   1
1   0   2
1   0   2
1   0   2
1   0   2
1   0   2
0   1   2

I need to find the max and sum of x and y for each category of z (z is like 1,2,…600). I use ddply from plyr for this:

library(plyr)
z.group<-ddply (sample.data,.(z),summarize,max_x=max(x), max_y=max(y), sum_x=sum(x), sum_y=sum(y))

z.group 
 z   max_x  max_y  sum_x    sum_y
  1    1    0   4   0
  2    1    1   5   1

Now, I need to insert these sum_x, sum_y, max_x, and max_y as the columns of sample.data under the related rows. For example, if max_x is 1 for z=1, then I insert max_x is 1 for all rows with z=1. The expected output is 

x   y   z   max_x  max_y    sum_x  sum_y
1   0   1   1   0   4   0
1   0   1   1   0   4   0
1   0   1   1   0   4   0
1   0   1   1   0   4   0
1   0   2   1   1   5   1
1   0   2   1   1   5   1
1   0   2   1   1   5   1
1   0   2   1   1   5   1
1   0   2   1   1   5   1
0   1   2   1   1   5   1

I wonder how do I get the expected output?

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    You can do it directly in one step , using transform

    .group<-ddply (sample.data,.(z),transform,max_x=max(x), max_y=max(y), sum_x=sum(x), sum_y=sum(y))
> z.group
   x y z max_x max_y sum_x sum_y
1  1 0 1     1     0     4     0
2  1 0 1     1     0     4     0
3  1 0 1     1     0     4     0
4  1 0 1     1     0     4     0
5  1 0 2     1     1     5     1
6  1 0 2     1     1     5     1
7  1 0 2     1     1     5     1
8  1 0 2     1     1     5     1
9  1 0 2     1     1     5     1
10 0 1 2     1     1     5     1
    • 0