[R] Replace with previous value

From: Ravi S. Shankar <ravis_at_ambaresearch.com>
Date: Wed, 26 Mar 2008 22:48:14 +0530

Hi R,

I have a dataframe with
[1] 435150 4

[1] "data.frame"
In the third column every time a number with "-" appears I need to replace with previous value
I am using the following code
s=which(substr(as.character(test[,3]),1,1)=="-")  for(i in 1:length(s)) test[s[i],3] = test[s[i]-1,3]

Is there a faster way of doing this?

R version 2.5.1 (2007-06-27)

LC_COLLATE=English_United States.1252;LC_CTYPE=English_United States.1252;LC_MONETARY=English_United
States.1252;LC_NUMERIC=C;LC_TIME=English_United States.1252

attached base packages:
[1] "stats" "graphics" "grDevices" "utils" "datasets"
[7] "base"

Thanks in advance

Ravi Shankar S  

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