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I have a data set of previous 3 month average stock returns of 200 firms for 92 months. Months are in rows and firms are in columns. Now i have to calculate mean of the top 20 percent of firms given that the values are non-zero. Following is the code: 

mmt1<-mean(as.numeric(comb[1,1:40]))

I need to know how to exclude zero values from mean calculation.

J_F
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Tayyaba Sami
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  • Welcome to StackOverflow! Please read the info about [how to ask a good question](http://stackoverflow.com/help/how-to-ask) and how to give a [reproducible example](http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example/5963610). This will make it much easier for others to help you. – Jaap Oct 27 '16 at 09:46

1 Answers1

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mmt1<-mean(as.numeric(comb[, which(colSums(comb)!=0)]))
user124123
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