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From: Andrew McDonald on 3 Jun 2010 15:29
Hi all,

Below is an example of the set of XYZ data I am working with:

XYZdata = [ 1 1 0.4
1 2 0.2
1 3 0
2 1 0
2 2 0.8
2 3 0.7 ]

I would like to find all Z values that are zero and replace the zero with the term 'No Data'. What is the best way to do this? I have been tinkering with cell arrays to no avail so far. I am working on some code to write this data to a text file, however the machine that I need to export this data to requires the zeroes to be shown as 'No Data' so it won't plot these points.

Thanks!

Andrew
From: Walter Roberson on 3 Jun 2010 15:41
Andrew McDonald wrote:

> Below is an example of the set of XYZ data I am working with:
>
> XYZdata = [ 1 1 0.4
> 1 2 0.2
> 1 3 0
> 2 1 0
> 2 2 0.8
> 2 3 0.7 ]
> I would like to find all Z values that are zero and replace the zero
> with the term 'No Data'. What is the best way to do this? I have been
> tinkering with cell arrays to no avail so far. I am working on some code
> to write this data to a text file, however the machine that I need to
> export this data to requires the zeroes to be shown as 'No Data' so it
> won't plot these points.

T = str2num(' %7g', XYZdata);
T(find(XYZData(:,3) == 0), end-6:end) = 'No Data';

Easier than I thought...

From: Andrew McDonald on 4 Jun 2010 08:49
I may be missing something, but I'm getting an error with the solution you posted, Walter. Not really sure what I'm doing wrong here, but I get an error with your first line due to too many input arguments in the str2num function, and even when I remove the ' %7g' input argument from the str2num function call I still get an error because my XYZdata matrix is a numerical matrix, not a string. I'm sorry that I didn't communicate that very well in my first post.

The matrix I am working with is a numerical matrix with three columns of data (x, y, and z). I need to write this data to a text file, but the caveat is that for every Z value that is equal to 0 I need to write to the file as 'No Data'.

How much more complicated does this become? As I mentioned before, I'm very novice at using cell arrays, but it seems to me that I will need to convert my numerical matrix to a cell array so I can maintain my integer data in columns 1 and 2 (x and y data) and have a mixture of double data and string data in column 3 (z data).

I really appreciate the help.
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