# [R] Using a 'for' loop : there should be a better way in R

From: John Kane <jrkrideau_at_yahoo.ca>
Date: Fri 25 Aug 2006 - 07:30:32 EST

I need to apply a yearly inflation factor to some wages and supply some simple sums by work category. I have gone at it with a brute force "for" loop approach  which seems okay as it is a small dataset. It looks a bit inelegant and given all the warnings in the Intro to R, etc, about using loops I wondered if anyone could suggest something a bit simpler or more efficent?

Example:

```cat1 <- c( 1,1,6,1,1,5)
cat2 <- c( 1,2,3,4,5,6)
cat3 <- c( 5,4,6,7,8,8)
cat4 <- c( 1,2,1,2,1,2)
```

years <- c( 'year1', 'year2', 'year3', 'year3', 'year1', 'year1')
id <- c('a','a','b','c','c','a')
df1 <- data.frame(id,years,cat1,cat2, cat3, cat4)

nn <- levels(df1\$id) # levels for outer loop hh <- levels(df1\$years) # levels for inter loop

mp <- c(1, 5, 10) # inflation factor

tt <- data.frame(matrix(NA, length(nn), 2)) names(tt) <- c("s1","s2")
rownames(tt) <- nn

for (i in 1:length(nn)){
scat <- data.frame(matrix(NA, length(hh),2)) dd1 <- subset(df1, id==nn[i])
for (j in 1:length(hh)){

```dd2 <- subset(dd1, dd1\$years==hh[j])
s1 <- sum(dd2\$cat1,dd2\$cat2, na.rm=T)
s2 <- sum(dd2\$cat3,dd2\$cat4,na.rm=T)
```

scat[j,] <- c(s1,s2) *mp[j] # multiply by the inflation factor
}

crush <- apply(scat, 2, sum)
tt[i,] <- crush
}

tt

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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Fri Aug 25 12:32:16 2006

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