how to convert a matix in .xlx specific julian day format?

The .mat file contains the data of max and min temperature. 1977 is the year 1 to 31 are the days, column 2to 13 have the max and min data of january to june (column 2 tmax, column 3 tmin of january). same furhter 6 months data is repeated at the bottom of matrix below. How can i convert this to 01/01/1977 to 12/31/1997 in 3 columns. first column as date,2nd as tmax and third as tmin. i have to repeat this process for multpile year like 1920 to 2015

Answer 1

[Arun]

Hey Mohsin,

I understand you would like to rearrange the ‘tmax’ and ‘tmin’ data along with the corresponding dates, where the data should be in ‘mm/dd/yyyy’ format. Currently, the data is organized into two sets, each containing data for six months.

“setDefaultFormats” function can be used to set the datetime to required format.

Here is a sample code that you can use to arrange the data to as required:

% get date for column 1 for required data 
datetime.setDefaultFormats('defaultdate','MM/dd/yyyy') 
startDate = datetime(1977,1,1); 
endDate = datetime(1977,12,31); 
dateValues = (startDate:endDate)'; 
% Extract data  
% get column 2 & 3 for the required data 
tempValues = [0 0];         %temprature values for 6 months 
tempValues = double.empty(tempValues); 
% random Sample data representing your 13 columns 
filedata = randi(12,31,13); 
for i=2:2:12 
    tempValues=[tempValues;filedata(:,i:i+1)]; 
end 

%similarly calculate the temp2Values for the next six months using correct row number 
%I am using the same values for next six months 
temp2Values=tempValues; 
tempCombined=[tempValues;temp2Values];     %data for 12 months
T=table; 
T=addvars(T,dateValues); 
T=addvars(T,tempCombined(1:365,1)); 
T=addvars(T,tempCombined(1:365,2)); 
T.Properties.VariableNames = ["Date","tmax", 'tmin']; 

%Output the data 
T

T = 365×3 table
       Date       tmax    tmin
    __________    ____    ____

    01/01/1977      1       1 
    01/02/1977      8       6 
    01/03/1977     11       8 
    01/04/1977      3       2 
    01/05/1977      3       9 
    01/06/1977     12      11 
    01/07/1977     12       3 
    01/08/1977      6       7 
    01/09/1977     12      10 
    01/10/1977     10       8 
    01/11/1977      7       4 
    01/12/1977      2       2 
    01/13/1977      5      11 
    01/14/1977      9       9 
    01/15/1977      5      11 
    01/16/1977     10       1 

For doing it for multiple years, use this code as a function with datafile and year as input and the result as output.

Please refer the shared MathWorks documentation link for more “setDefaultFormats” related details: https://www.mathworks.com/help/matlab/matlab_prog/set-display-format-of-date-and-time-arrays.html

Hope this helps.