[R] calculate difference of consecutive cells in vector

Max Kauer MaximilianOtto at gmx.at
Wed Mar 22 21:35:34 CET 2006

in dataframe I want to subtract the "next" value in the list from the former
one to get this:

name     var1  output
a           9    506
b         515    512
c        1027    453

so I subtract: table$var1[2]-table$var1[1] and write it into table$output[1]

I did this with:
for (i in 1:(length(table$var1)){
	table$output[i] <- table$var1[i+1]-table$var1[i] }

it works but it get extremely slow for a large table.

I bet there is a better way to do this in R with "sapply" or something
similiar, but I couldn't figure out how.

I'd apprechiate any idea

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