R help - Jun 2009 - Warning messages when using rbind

Hello,

I have been using a very simple rbind approach (simple enough for me to
understand) to combine data files within R.

It seems to work fine, but then generates warning messages for reasons that
I can't begin to understand.  The text below shows the issue.  

testread12=read.table("C:/Files/Test100.txt", head = T)
testread11=read.table("C:/Files/Test101.txt", head = T)
testbind1=rbind(testread12,testread11)
testbind2=rbind(testread11,testread12)

The testrbind1 line generates the following message:

"Warning message:
In `[<-.factor`(`*tmp*`, ri, value = c(0.00557998, -0.058016069,  :
  invalid factor level, NAs generated"

However the testrbind2 line works fine.  Although the data in the files is
different, the format (columns, etc) should be identical.  The fact that it
works in one order, but not the other, makes it very difficult for me to
understand what the problem is.

Files attached.  Any suggestions gratefully received.  Thanks,

Guy Green
http://www.nabble.com/file/p24130996/Test101.txt Test101.txt 
http://www.nabble.com/file/p24130996/Test100.txt Test100.txt 
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Hi,


You seem to have a glitch in one file,

testread12=read.table("Test100.txt", head = T)
str(testread12) # Column131 is converted to a factor
 # $ Column131: Factor w/ 2920 levels "--","-0.000122393",..

combining the second data set with this one will convert the new data 
into factor for this column but some (most) levels were not present in 
the first file.

HTH,

baptiste

gug wrote:
> Hello,
>
> I have been using a very simple rbind approach (simple enough for me to
> understand) to combine data files within R.
>
> It seems to work fine, but then generates warning messages for reasons that
> I can't begin to understand.  The text below shows the issue.  
>
> testread12=read.table("C:/Files/Test100.txt", head = T)
> testread11=read.table("C:/Files/Test101.txt", head = T)
> testbind1=rbind(testread12,testread11)
> testbind2=rbind(testread11,testread12)
>
> The testrbind1 line generates the following message:
>
> "Warning message:
> In `[<-.factor`(`*tmp*`, ri, value = c(0.00557998, -0.058016069,  :
>   invalid factor level, NAs generated"
>
> However the testrbind2 line works fine.  Although the data in the files is
> different, the format (columns, etc) should be identical.  The fact that it
> works in one order, but not the other, makes it very difficult for me to
> understand what the problem is.
>
> Files attached.  Any suggestions gratefully received.  Thanks,
>
> Guy Green
> http://www.nabble.com/file/p24130996/Test101.txt Test101.txt 
> http://www.nabble.com/file/p24130996/Test100.txt Test100.txt 
>   

-- 
_____________________________

Baptiste Augui?

School of Physics
University of Exeter
Stocker Road,
Exeter, Devon,
EX4 4QL, UK

Phone: +44 1392 264187

http://newton.ex.ac.uk/research/emag