Complicated For Loop (to me)

Since you did not follow the posting and provide data, here is a way
that you can split by race & region and perform operations on each
subset of the data frame:
# test data
n <- 4500
x <- data.frame(race=sample(c('a','b','c'), n, TRUE),
+                 region=sample(1:9, n, TRUE), values=runif(n))
# split into race & region
x.s <- split(x, list(x$race, x$region), drop=TRUE)
# average for each subset
sapply(x.s, function(.df) mean(.df$values))
a.1       b.1       c.1       a.2       b.2       c.2       a.3
     b.3       c.3       a.4
0.4832214 0.4792623 0.4846138 0.5098792 0.4997666 0.5212905 0.5068535
0.5140438 0.5580490 0.4849455
      b.4       c.4       a.5       b.5       c.5       a.6       b.6
     c.6       a.7       b.7
0.4952947 0.4639553 0.4798192 0.5030650 0.4889465 0.4839610 0.5080325
0.5176548 0.4788206 0.5300395
      c.7       a.8       b.8       c.8       a.9       b.9       c.9
0.4799252 0.4871341 0.4675535 0.4899783 0.5172642 0.4968789 0.5499326

I've looked through ?split and run all of the code, but I am not sure that I
can use it in such a way to make it do what I need. ?Another suggestion was
using "lists", but again, I am sure that the process can do what I need, but
I am not sure it would work with so many observations.

I might have been too simple in my code. ?Let me try to explain it more
clearly:

I've got a data set of 4500 observations. ?I have already subset it into
race/ethnicity (which I did by simple code). ?Now I needed to subset each
race/ethnicity again into 9 separate regions. ?I again did this by simple
code.

The problem is now, I need to calculate a percentage for three different
variables for all 9 regions for each race. ?I was trying to do this through
a loop command.

So a snippet of my code is :

names <- c("white", "black", "asian", "hispanic")
for(j in 1:length(names)){
for(i in 1:9){
names[j].cd[i].es.wash <- subset(names[j].cd[i], SLUNCH==1)
es.cd[i].names.w <-
sum(names.cd[i].es.wash$NWEIGHT)/sum(names.cd[i]$NWEIGHT)
}
}

Maybe that makes it clearer. ?If not, I apologize. ?Thanks for the help that
I have already received. ?It is greatly appreciated.

Tony

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and provide commented, minimal, self-contained, reproducible code.

Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?

Complicated For Loop (to me)

Thread (9 messages)