Delete row from struct on string condition

Hi all, I try to remove rows from a dataset structure based on a condition in a string. I converted a cell array to a structure. The first field of the structure is 'Country', here country codes are listed as strings. The other 12 columns contain numbers (doubles) of railway usage during the last years. Now I want to delete rows from the structure that have a specific countrycode (because the other dataset (ie. length of railwaylines) doesn't have data for that country). However I can't seem that to work. Country codes that need to be deleted: 'CY', 'EU27', 'EU28', 'LI', 'ME' and 'MT'.

For example for the country 'CY' I tried this:

for i = 1:size(PaxUsage_struct,2)
      if isequal(PaxUsage_struct(i).Country,'CY')
          PaxUsage_struct(i) = []
      end
  end

However the code

isequal(PaxUsage_struct(i).Country,'CY')

does seem to work, when I type it in the command window myself (with i = 6) it returns 1, with i = 5 it returns 0. So now row 6 needs to be removed. So why does the removing not work?

Running the script does not return an error, just nothing changes in the structure.

Answer 1

[Stephen23]

You should simply use ismember:

idx = ismember({PaxUsage_struct.Country}, {'CY', 'EU27', 'EU28', 'LI', 'ME','MT'});
PaxUsage_struct = PaxUsage_struct(~idx);

Answer 2

[Jan]

This is a bad idea:

for i = 1:size(PaxUsage_struct,2)
    if isequal(PaxUsage_struct(i).Country,'CY')
        PaxUsage_struct(i) = []
    end
end

Imagine the PaxUsage_struct(2) is removed. Then PaxUsage_struct is shorter and the loop will fail, when it runs until the original size(PaxUsage_struct,2). Better:

toRemove = strcmp({PaxUsage_struct.Country}, 'CY');
PaxUsage_struct(toRemove) = [];

I cannot follow your explanations concerning "does seem to work". Please provide some test data or use the debugger to examine this by your own.