Loop for CrossTable (gmodels)

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.

David Winsemius
Alameda, CA, USA

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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David Winsemius
Alameda, CA, USA