Datenum Mystery - different date formats - but results are the same

Question

Ms. Mat 2012-12-23

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/57254-datenum-mystery-different-date-formats-but-results-are-the-same

Background

I have an excel sheet with different date formats (in excel some are in General format, some in date format totally random)

example: 10/05/2005 , 10/5/2005, 10/05/05, 05/12/2005 and so on.

I read the XL file into MATLAB as follows:

[dta_num , dta_txt , dta_raw] = xlsread(...)

I need to work with the dates in the excel sheet subsequently.

Actual Problem

I tried out the following commands

datenum('10/5/2005') datenum('10/05/2005') datenum('10/05/05') datenum(dta_txt(2,2))

All of them return the same answer. (732590) But I realized that 732590 is read as 05-Oct-2005 when I ran

datestr(732590)

However the dates in my data sheet needs to be read as dd/mm i.e 10-May-2005.

If I choose to specify the format, datenum('10/5/2005','dd/mm/yyyy') ans = 732442 datenum('10/05/2005','dd/mm/yyyy') ans = 732442 datenum('10/05/05','dd/mm/yyyy') ans = 1957

Originally I thought I will convert the dates using datenum and the after my manipulations using functions such as month(datenum(dta_txt(2,2),'dd/mm/yyyy')) I will use datestr and I will have all the dates in the same format. But now I am back to square 1 since datestr(1957) gives me a 2 digit year.

Is the only solution is to go over the length of the dta_txt contents using cellfun('length',dta_txt(:,2)) and change it to 4 year format.

To summarize my requirements are;

1. date format which takes less resource as I might want to extract and make comparisons of the the month and year later. 2. Have a consistent date format preferably dd/mm/yyyy.