Formating strings using named tokens

With regexp a struct can be obtained with named tokens where all information about the token names is in the expression (https://nl.mathworks.com/help/matlab/ref/regexp.html#btqhkwj-7)

Example:

str = '01/11/2000  20-02-2020  03/30/2000  16-04-2020';
expression = ['(?<month>\d+)/(?<day>\d+)/(?<year>\d+)|'...
              '(?<day>\d+)-(?<month>\d+)-(?<year>\d+)'];
tokenNames = regexp(str,expression,'names');
for k = 1:length(tokenNames)
   disp(tokenNames(k))
end

    month: '01'
      day: '11'
     year: '2000'

    month: '02'
      day: '20'
     year: '2020'

    month: '03'
      day: '30'
     year: '2000'

    month: '04'
      day: '16'
     year: '2020'

I am now looking for the inverse: specify this expression, and fill in the tokens at the correct location.(like formatting in python https://docs.python.org/3/tutorial/inputoutput.html)

I want to do something like:

tokenName.month = '02' 
tokenName.day = '20' 
tokenName.year = '2020'
sprintf('(?<month>\d+)/(?<day>\d+)/(?<year>\d+)', tokenName)

Results:

2020/20/02

My usecase is that I define pattern in one location in my scripts to parse filenames, and that in a later moment I want to generate comparable filenames. It is very convinient to have to specify that only once, and not twice with slightly different notation.

Answer 1

[Star Strider]

I am not exactly certain what you want.

Using an anonymous function is one option --

DMY = @(d,m,y) sprintf('%02d-%02d-%4d',d,m,y);

day = 19;
month = 1;
year = 1807;

str = DMY(day,month,year)

str = '19-01-1807'

.

[Vasco]

See original question for a clarification

Answer 2

[Stephen23]

Given:

tokenName.month = '02';
tokenName.day   = '20';
tokenName.year  = '2020';

expr = '(?<month>\d+)/(?<day>\d+)/(?<year>\d+)';

You could do:

out = regexprep(expr, '\(\?<(\w+)>[^)]*\)', '${tokenName.($1)}')

out = '02/20/2020'