[R] 2 Seemingly Simple Problems

MATT BORKOWSKI mpb170 at psu.edu
Fri May 31 15:25:41 CEST 2002

Alright...these two issues seem rather simple.  But I had trouble finding much 
about either of them in the archives.

1)  Using scan()
I'm trying to use scan to read in a large data set since read.table() is taking 
quite a bit of time.  But when I try to do this I receive a error message along
the lines of "Character where numeric expected."  Seems to me the problem is
arising because my data is composed of both characters and numbers, but R
is only expecting numerics.  I assume the key to this problem lies in the
"what=" parameter.  But I'm not sure what to set this to so that R expects 
characters or numbers.

2) Testing for 'NA' values
In this problem I have read in a large data set.  Some of the lines of data are
not as long and therefore the last few columns have been filled in with 'NA.'  
Now I'm trying to read through rows of data backwards because the parameter
I'm trying to extract from the data.frame is not always in column 5 but is always
the second real value after the 'NA's' if that makes any sense.  But I don't think
that's all that important anyway.  The point is...I'm trying to extract the second
value after the 'NA' values by ignoring the 'NA' values and couting any real
values.  I'm trying to accomplish this with:

if(data[r,c] != NA)  count <- count +1

However, I receive the error: "Value missing where logical expected".  I assume
this is happening because I'm testing for 'NA' values.  Is there anyway around
this?  Is there a way to count the number of 'NA' numbers or a way to skip over 

Thanks for you time,

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