# Re: [R] write a loop for tallies

From: Erik Iverson <eriki_at_ccbr.umn.edu>
Date: Thu, 24 Jun 2010 18:13:36 -0500

On average, any data manipulation that can be described in a sentence or two of English can be programmed in one line in R. If you find yourself writing a long 'for' loop to do something that sounds simple, take a step back and research if an existing combination of functions can easily handle your request.

john polo wrote:
> Dear R users,
>
> I have a list of numbers such as
>
> > n
> [1] 3000 4000 5000 3000 5000 6000 4000 5000 7000 5000 6000 7000
>
> and i'd like to set up a loop that will keep track of the number of
> occurences of each of the values that occur in the list, e.g.
>
> 3000: 2
> 4000: 2
> 5000: 4
>
> I came up with the following:
>
> a<- for (i in 1:length(n)) {
> r<-0
> s<-0
> t<-0
> u<-0
> v<-0
> ifelse(n[i] == "3000", r <- r+1,
> ifelse(n[i] == "4000", s <- r+1,
> ifelse(n[i] == "5000", t <- r+1,
> ifelse(n[i] == "6000", u <- r+1,
> ifelse(n[i] == "7000", v <- r+1, NA)))))
> r<-sum(r)
> s<-sum(s)
> t<-sum(t)
> u<-sum(u)
> v<-sum(v)
> cat("r = ", r, "\n")
> cat("s = ", s, "\n")
> cat("t = ", t, "\n")
> cat("u = ", u, "\n")
> cat("v = ", v, "\n")
> }
>
> However, this is the output:
>
> r = 1
> s = 0
> t = 0
> u = 0
> v = 0
> r = 0
> s = 1
> t = 0
> u = 0
> v = 0
> r = 0
> s = 0
> t = 1
> u = 0
> v = 0
> r = 1
> s = 0
> t = 0
> u = 0
> v = 0
> r = 0
> s = 0
> t = 1
> u = 0
> v = 0
> r = 0
> s = 0
> t = 0
> u = 1
> v = 0
> r = 0
> s = 1
> t = 0
> u = 0
> v = 0
> r = 0
> s = 0
> t = 1
> u = 0
> v = 0
> r = 0
> s = 0
> t = 0
> u = 0
> v = 1
> r = 0
> s = 0
> t = 1
> u = 0
> v = 0
> r = 0
> s = 0
> t = 0
> u = 1
> v = 0
> r = 0
> s = 0
> t = 0
> u = 0
> v = 1
>
> How should i write this loop, please? I've tried variations with "if"
> instead of "ifelse" and receive errors about "unexpected {" or
> "unexpected )".
>
> regards,
> john
>
> ______________________________________________
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R-help_at_r-project.org mailing list
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 Thu 24 Jun 2010 - 23:16:37 GMT

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