On May 12, 2013, at 10:44 AM, David Winsemius wrote:
>
> On May 12, 2013, at 10:30 AM, arun wrote:
>
>> Hi,
>> According to the error, the variables should have the same length.
>> For example:
>> set.seed(24)
>> dat1<-
>> cbind(RACE=sample(1:10,10,replace=TRUE),as.data.frame(matrix(sample(1:100,20*10,replace=TRUE),ncol=20)))
>> lapply(dat1[,-1],function(x)
>> CrossTable(x,dat1$RACE,format="SPSS",prop.chisq=FALSE,digits=2,dnn=c("VAR","RACE")))
>> # prints cross tables.
>>
>> #or
>> lapply(names(dat1)[-1],function(x)
>> CrossTable(dat1[,x],dat1[,"RACE"],format="SPSS",prop.chisq=FALSE,digits=2,dnn=c(x,"RACE")))
>> A.K.
>>> Hi,
>>>
>>> I have 20 variables in a data frame (VAR1 ... VAR20) which I would like to
>>> crosstab against the variable RACE.
>>> I would like to use a loop structure instead of 20 statements like:
>>> CrossTable(VAR1, RACE, format = "SPSS", prop.chisq = FALSE, digits = 2)
>>>
>>>
>>> I have tried following syntax, but failed:
>>>
>>> library(gmodels)
>>> for(i in 1:20){
>>> columnname <- ("VAR",i)
>>> CrossTable(columnname, RACE, format = "SPSS", prop.chisq = FALSE, digits =
>>> 2)
>>> }
>>>
>>> I receive following Error:
>>> Error in CrossTable(columnname, RACE, format = "SPSS", prop.chisq = FALSE,
>>> :
>>> x and y must have the same length
>
> It might be productive in learning R to understand what you were doing wrong
> and how you could have used that control for-loop structure. It does appear
> that you have `attach`-ed a data.frame and are referring to the column names.
> Yes? If so, you should realize that is not a particularly safe practice, but
> let's push on.
>
> columnname is just a character vector with a single element, "VAR1" the
> first time around. R does not do a double-evaluation to first figure out that
> `columnname` is "VAR1" and then proceed further to look up its value. To do
> that you would need to add `get`:
>
> for(i in 1:20){
> columnname <- ("VAR",i)
> CrossTable( get(columnname), RACE, format = "SPSS", prop.chisq = FALSE,
> digits = 2)
> }
>
> The get function does the extra step of converting the character value to an
> object name and returning the value of that named data-object.
>
>>> Any idea how to get 20 crosstables within a loop?
>
> That should do it. It would have been better if you had used dput() to
> produce a workable small example of a few of the columns.
(I probably should have made it clear that the "you" I was addressing was
Stefan, whose message has not yet shown up on my mail-client but to whom Arun
was responding to the list. I see a lot of messages from Arun that are
responses to messages that never make it to the list. I guessed (correctly) he
was replying to Nabble postings that are blocked because of the filters on the
Nabble-spam-conduit. So in this case the original message may never make it to
the archives, because I just cleared the moderation queue of a single spam
message and did not see the original posting.)
Actually that single revision to the argument to CrossTable won't do it. When I
built my own data example, I also find that Stefan failed to properly construct
`columnname` using paste0 and didn't do anything with the value of CrossTable.
Since for() is a function, the value needs to either be printed or saved as
something.
res<-list()
for(i in 1:3){
columnname <- paste0("VAR",i)
res[[i]] <- CrossTable( get(columnname), RACE, format = "SPSS", prop.chisq =
FALSE, digits = 2)
}
res[[1]]
Cell Contents
|-------------------------|
| Count |
| Row Percent |
| Column Percent |
| Total Percent |
|-------------------------|
Total Observations in Table: 10
| RACE
get(columnname) | 1 | 2 | 3 | Row Total |
----------------|-----------|-----------|-----------|-----------|
3 | 0 | 0 | 1 | 1 |
| 0.00% | 0.00% | 100.00% | 10.00% |
| 0.00% | 0.00% | 20.00% | |
| 0.00% | 0.00% | 10.00% | |
----------------|-----------|-----------|-----------|-----------|
4 | 0 | 0 | 2 | 2 |
| 0.00% | 0.00% | 100.00% | 20.00% |
| 0.00% | 0.00% | 40.00% | |
| 0.00% | 0.00% | 20.00% | |
----------------|-----------|-----------|-----------|-----------|
7 | 0 | 0 | 1 | 1 |
| 0.00% | 0.00% | 100.00% | 10.00% |
---- snipped rest of output.
>
> David Winsemius
> Alameda, CA, USA
>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
David Winsemius
Alameda, CA, USA
______________________________________________
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