Hello,
I have a dataframe (obtained from read.table()) which looks like
ExpA ExpB ExpC Size
1 12 23 33 1
2 12 24 29 1
3 10 22 34 1
4 25 50 60 2
5 24 53 62 2
6 21 49 61 2
now I want to take all rows that have the same value in the "Size"
column and apply a function to the columns of these rows (for example
median()). The result should be a new dataframe with the medians of the
groups, like this:
ExpA ExpB ExpC Size
1 12 23 34 1
2 24 50 61 2
I tried to play with the functions by() and tapply() but I didn't get
the results I wanted so far, so any help on this would be great!
The reason why I am having this problem: (I explain this just to make
sure I don't do something against the nature of R.)
I am doing 3 simillar experiments, A,B,C and I change a parameter in the
experiment (size). Every experiment is done multiple times and I need
the median or average over all experiments that are the same. Should I
preprocess my data files so that they are completely different? Or is it
fine the way it is and I just overlooked the simple solution to the
problem described above?
Regards,
Timo
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