detecting null values in a CSV file

Hello all,

I have a CSV file, that is 2411 columns wide. There are certain instances in
teh file, where null values are located. That is: two commas together,
without anything in the middle. In a certain section, the only possible
values are NULL, 0,1,and 2. I need to be able to detect these NULL's and be
able to have them counted. For example, in a frequency table. How can I
accomplish this?

Thanks in advance for the help.

--
Jason Thibodeau

       [[alternative HTML version deleted]]

On a related note, I am trying to do some matching using conditional
statements. These NULL values are being brought in to my data frame as NA,
as expected, but in a conditional if() statement, I cannot compare then to a
integer value, it fails the program. Here is a small snippet of where the
error occurs.

 while(col_loop<1570)
                       {
                               data_filter <- data[c(col_loop)]
                               print(data_filter)
                               if(data_filter == trigger)
                               {
                                       trigger_count <- trigger_count +1
                               }
                               col_loop <- col_loop +1

                       }

Here: trigger_count, and trigger are both integers. The print statement was
debug to see why it was failing and this is what it returned:
<snip>
 V1415
1     0
 V1416
1     0
 V1417
1     1
 V1418
1     1
 V1419
1     1
 V1420
1    NA
Error in if (data_filter == trigger) { :
 missing value where TRUE/FALSE needed

Thanks for any help you can provide.

On Thu, Sep 18, 2008 at 2:12 PM, Hutchinson,David [PYR] <
David.Hutchinson at ec.gc.ca> wrote:

Try length(na.omit(<the particular data column>))

Here's an example:

data <- runif(100,0,10)
data[runif(20,0,100)] <- NA
file.contents <- matrix(data, ncol = 5, byrow = TRUE)
for (i in 1:5) {
 print (length(na.omit(file.contents[,i])))
}


-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of Jason Thibodeau
Sent: Thursday, September 18, 2008 10:12 AM
To: r-help at r-project.org
Subject: [R] detecting null values in a CSV file

Hello all,

I have a CSV file, that is 2411 columns wide. There are certain
instances in
teh file, where null values are located. That is: two commas together,
without anything in the middle. In a certain section, the only possible
values are NULL, 0,1,and 2. I need to be able to detect these NULL's and
be
able to have them counted. For example, in a frequency table. How can I
accomplish this?

Thanks in advance for the help.

--
Jason Thibodeau

        [[alternative HTML version deleted]]

--
Jason Thibodeau

       [[alternative HTML version deleted]]