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rdataframesumrowlong-format-data

calculate the sum in a data.frame (long format)

I want to calculate the sum for this data.frame for the years 2005 ,2006, 2007 and the categories a, b, c.

year <- c(2005,2005,2005,2006,2006,2006,2007,2007,2007)
category <- c("a","a","a","b","b","b","c","c","c")
value <- c(3,6,8,9,7,4,5,8,9)
df <- data.frame(year, category,value, stringsAsFactors = FALSE)

The table should look like this:

year category value
2005 a 1
2005 a 1
2005 a 1
2006 b 2
2006 b 2
2006 b 2
2007 c 3
2007 c 3
2007 c 3
2006 a 3
2007 b 6
2008 c 9

Any idea how this could be implemented? add_row or cbind maybe?

Solution

  • A base R solution using aggregate

    rbind( df, aggregate( value ~ year + category, df, sum ) )

   year category value
1  2005        a     3
2  2005        a     6
3  2005        a     8
4  2006        b     9
5  2006        b     7
6  2006        b     4
7  2007        c     5
8  2007        c     8
9  2007        c     9
10 2005        a    17
11 2006        b    20
12 2007        c    22