Remove leading zeros from dates strings

Hello

I need to find the number of times a set of dates is included in a large text file. The problem is that the text file does not use leading zeros for months and days.

My code should look something like this:

myText=fileread('largeFile.txt');
dayOne=datetime('06/05/20','InputFormat','MM/dd/yy')
for it=1:10
    numberOfTimes(it)=size(regexp(myText, datestr(dayOne+days(it), 'mm/dd/yy')), 2);
end

Thanks

[jonas]

Why not simply count the dates with hist?

Answer 1

[jonas]

You can use histogram() to count occurences, either with datetime or categoricals as input.

dates = datetime(2010,1,12) + rand(1000,1)*days(365);

% with categoricals
dates_cell = cellstr(datestr(dates,'mm/dd/yy'));
dates_cat = categorical(dates_cell);
H = histogram(dates_cat)

[Santiago Costantino]

Thank you Jonas. My problem is not about how to count the occurrences, but how to generate date strings that lack the leading zeros for months and days as in the text file.

[Walter Roberson]

You could use mm and then use regexp to strip out leading 0. But it hardly seems worth it considering that datetime() can handle the situation

dates = datetime(2010,1,12) + rand(10,1)*days(365);
dates.Format = 'M/d/yy';
dates_cat = categorical(cellstr(dates));
histogram(dates_cat);

[Santiago Costantino]

That does it. Thank you, Walter.

Answer 2

[Steven Lord]

Use M instead of MM and d instead of dd in the input format. According to the description of the Format property on the documentation page (which is referenced in the documentation for 'InputFormat'), M handles "Month, numerical using one or two digits" as opposed to MM which handles "Month, numerical using two digits".

>> datetime('07-16-2020', 'InputFormat', 'M-dd-yyyy')
ans = 
  datetime
   16-Jul-2020

>> datetime('7-16-2020', 'InputFormat', 'M-dd-yyyy')
ans = 
  datetime
   16-Jul-2020

[Santiago Costantino]

Sorry, I guess my question was not clear enough.

The dates in the text file are written as '4/7/20' for April 7th 2020. I need to find the number of occurrences of each one of many different and consecutive dates in the text.