R help - Feb 2011 - substring and paste character with a for loop

Hello R users,

I have a little problem with a for loop.
Below there is an simple example of my problem.

I want to delet the commas in the character string. Fore this reason I
create a for loop to unpick the string and rebuild him without the commas.
The problem is, that "paste" does not work in the loop as I expected.

text <- "aaa,bbb,ccc,ddd"

characterseq <- seq(1,15,4)

for (i in characterseq ){
m <- paste(substring(text,i,i+2),sep = "")
}
> m
[1] "ddd"


m should be "aaabbbcccddd" and not just "ddd"



with best regards

Chris
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Chris82 <rubenbauar <at> gmx.de> writes:
> 
> 
> Hello R users,
> 
> I have a little problem with a for loop.
> Below there is an simple example of my problem.
> 
> I want to delet the commas in the character string. Fore this reason I
> create a for loop to unpick the string and rebuild him without the commas.
> The problem is, that "paste" does not work in the loop as I
expected.
> 
> text <- "aaa,bbb,ccc,ddd"
> 
> characterseq <- seq(1,15,4)
> 
> for (i in characterseq ){
> m <- paste(substring(text,i,i+2),sep = "")
> }
> 
> > m
> [1] "ddd"
> 
> m should be "aaabbbcccddd" and not just "ddd"
> 
  If you want to delete commas, what about

 gsub(",","",c("aaa,bbb,ccc,ddd"))
[1] "aaabbbcccddd"

?

  The problem with your loop is that you are not building m; you
would need paste(m,substring(text,i,i+2),sep="")

Hi Chris,
'gsub' does exactly what you want:

gsub(",","",text)

so there is no need for a loop.

Btw. your loop assigns a new value to m in each step and you see only
the last assignment.
you could do something like

m <- paste(m,substring(text,i,i+2),sep = "")

hth

Am 03.02.2011 17:35, schrieb Chris82:
> 
> Hello R users,
> 
> I have a little problem with a for loop.
> Below there is an simple example of my problem.
> 
> I want to delet the commas in the character string. Fore this reason I
> create a for loop to unpick the string and rebuild him without the commas.
> The problem is, that "paste" does not work in the loop as I
expected.
> 
> text <- "aaa,bbb,ccc,ddd"
> 
> characterseq <- seq(1,15,4)
> 
> for (i in characterseq ){
> m <- paste(substring(text,i,i+2),sep = "")
> }
> 
>> m
> [1] "ddd"
> 
> 
> m should be "aaabbbcccddd" and not just "ddd"
> 
> 
> 
> with best regards
> 
> Chris

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