I have a table (data.frame) with numerical data & factors data of which several are character variables (e.g. 'species', 'Fam_name', 'gear') where I want to calculate the subtotals (sum) for the 'weight' and 'number' variables for each 'ss'.
I have tried using the 'aggregate' function, but I have failed to get it to return the character value for the 'gear' variable.
Below is the head of my table
survey station ss species weight number bdep lon lat Sci_name Fam_name gear
1 2012901 1 2012901001 CARSC04 11.20 20 23 37.61650 19.14900 Scomberoides lysan CARANGIDAE TB
2 2012901 1 2012901001 SCMGR02 0.98 2 23 37.61650 19.14900 Grammatorcynus bilineatus SCOMBRIDAE TB
3 2012901 2 2012901002 NOCATCH 0.00 0 6 38.48333 18.71667 NO CATCH NO CATCH TB
4 2012901 3 2012901003 LUTLU06 5.65 1 6 38.48333 18.71667 Lutjanus bohar LUTJANIDAE TB
5 2012901 3 2012901003 SHACAB1 4.00 1 6 38.48333 18.71667 Triaenodon obesus CARCHARHINIDAE TB
6 2012901 4 2012901004 NOCATCH 0.00 0 9 38.48333 18.71667 NO CATCH NO CATCH TB
I tried using the following code with the intent of combining the two using bind,
catch1<-aggregate(cbind(weight, number) ~ ss, data = catch, FUN = sum)
catch2<-aggregate(cbind(survey, station, bdep, lon, lat, gear) ~ ss, data = catch, FUN=median)
but while the first line does what I want it to - sums for each 'ss', the other results in numerical median for 'gear' whereas I want it to return the 'gear' code for that particular 'ss'.
Reconstruction of the 'gear' factor (thanks to BrodieG):
catch2$gear <- factor(levels(catch$gear)[catch2$gear], levels=levels(catch$gear))
Problem solved :-)
Your problem is that gear is a factor, so median is returning the median of the numerical values of the factor. Try:
catch2$gear <- factor(levels(catch$gear)[catch2$gear], levels=levels(catch$gear))
or something like it to reconstruct the factor for catch2.