MATLAB: How to read PRE tag and create cellarray with NaN - regex

Question

I am trying to read data from html file
The data are delimmited by <PRE></PRE> tag
e.g.:
<pre>
12.0 29132 -60.3 -91.4 1 0.01 260 753.2 753.3 753.2
10.0 30260 -57.9 1 0.01 260 58 802.4 802.5 802.4
9.8 30387 -57.7 -89.7 1 0.01 261 61 807.8 807.9 807.8
6.0 33631 -40.4 -77.4 1 0.17 260 88 1004.0 1006.5 1004.1
5.9 33746 -40.3 -77.3 1 0.17 1009.2 1011.8 1009.3
</pre>
t = regexp(html, '<PRE[^>]*>(.*?)</PRE>', 'tokens');
where t is a cell of char
Well, now I would to replace the blank space with NaN and to obtain:
12.0 29132 -60.3 -91.4 1 0.01 260 Nan 753.2 753.3 753.2
10.0 30260 -57.9 Nan 1 0.01 260 58 802.4 802.5 802.4
9.8 30387 -57.7 -89.7 1 0.01 261 61 807.8 807.9 807.8
6.0 33631 -40.4 -77.4 1 0.17 260 88 1004.0 1006.5 1004.1
5.9 33746 -40.3 -77.3 1 0.17 NaN NaN 1009.2 1011.8 1009.3
This data will be saved on mydata.dat file

Answer 1

If you have the HTML file hosted somewhere, then:
url = 'http://www.myDomain.com/myFile.html';
html = urlread(url);
% Use regular expressions to remove undesired HTML markup.
txt = regexprep(html,'<script.*?/script>','');
txt = regexprep(txt,'<style.*?/style>','');
txt = regexprep(txt,'<pre.*?/pre>','');
txt = regexprep(txt,'<.*?>','')
Now you should have the date in text format in txt variable. You can use textscan to parse the txt var and you can scan for the whitespace or for the numbers.
More Info:
- urlread
- regexprep

Answer 2

This isn't the perfect solution but it seems to get you there.
Assuming t is one long string, the delimiter is white space, and you know the number of columns:
numcols = 7;
sample = '1 2 3 4 5 7 1 3 5 7';
test = textscan(sample,'%f','delimiter',' ','MultipleDelimsAsOne',false);
test = test{:}; % Pull the double out of the cell array
test(2:2:end) = []; % Dump out extra NaNs
test2 = reshape(test,numcols,length(test)/numcols)'; % Have to mess with it a little to reshape rowwise instead of columnwise
Returns:
test2 =
1 2 3 4 5 NaN 7
1 NaN 3 NaN 5 NaN 7
This is assuming the delimiter is white space and constant. Textscan doesn't allow you to stack whitespace as a delimiter, so it throws a NaN after each white space character if there isn't data present. In your example data there are two white space characters between each data point, so every other NaN (or, more generically, n_whitespace - 1) can be thrown out, leaving you with the NaNs you actually want.