[R] By function

From: Raoni Rodrigues <caciquesamurai_at_gmail.com>
Date: Thu, 07 Apr 2011 18:38:53 -0400


Hello all!

I have a data frame with nine variables and 293 cases. (attached goes the csv file).

I need to calculate a index using the sum of one variable (N) divided by the length of other variable (Fisherman), but for each day (Date).

I tried to use that codes:

by (cpue, cpue$Date, function (x) sum (cpue$N)/length(cpue$Fisherman))

tapply (cpue$Data, cpue$Data, function (x) {sum (x)/length(y)})

In both codes, as result, I received the same value for all Date value. And, oddly, this result is the value of calculation for all data frame, as I used just:

sum (cpue$N)/length(cpue$Fishermans)

Sorry for the basic question, but I worked on this simple code all day and can't do it work out! And have no idea why...

I'm using R 2.11 in Windows XP.

Since now, thanks for the attention and all help,

Best,

Raoni



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