MATLAB Answers


Naming individual fields in a struct

Asked by mashtine on 24 Feb 2014
Latest activity Edited by Walter Roberson
on 24 Feb 2014
Hi everyone,
I have this block of code:
HWFiles = {'midas_wind_197901-197912.txt',............'midas_wind_201301-201312.txt'};
for k=1:numel(HWFiles);
fid = fopen(HWFiles{k}, 'r');
tmp = textscan(fid,'%s %*s %*f %*f %*s %*f %f %*f %f %f %f %f %f %*f %*f %*f %*f %*f %*f %*f %*f %*s %*f', 'Delimiter',',');
HWData(k).data = tmp ;
Not pasting well sorry. HWData becomes a 1 x 35 struct and I wanted to change each field name to the year from the file, eg 1979, 1980 .... 2013. Any ideas with this?


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2 Answers

Answer by Walter Roberson
on 24 Feb 2014
 Accepted Answer

Are you asking to create a structure of length 1, HWData, with field names 1979, 1980, and so on? If so then you cannot do that as field names must start with a letter. If you wanted to be able to look up by year then you could use a common prefix such as 'Y', so Y1979, Y1980, and so on. Or you could use
TO use the prefix,
prefix = 'Y';
and in the loop,
filename = HWFiles{k};
underpos = find(filename, '_', 1, 'last');
fieldname = [prefix filename(underpos+1:underpos+3)];
HWData.(fieldname) = tmp;


I got this fixed by removing the 1 in the filename and adjusting the parameters used in the fieldname. Thank you!
However, I believe indexing this in a loop to manipulate and work with the data is probably a bit too complicated (or perhaps I just don't know it yet)
Opps, should have had
underpos = find(filename == '_', 1, 'last');
Indexing by a non-consecutive number (eg. year) to work in a loop is going to be very nearly as much trouble.
Recall that you can use fieldnames() to get the names of the fields. And sort() of a cell array of strings would give the fieldnames sorted numerically provided they were all the same length.

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Answer by Image Analyst
on 24 Feb 2014

If you have R2013b, why not use a table. You can use struct2table to convert your structure to a possibly more convenient table. Table is a brand new data type.

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I wish I could but I am stuck with R2010 unfortunately.

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