MATLAB: Help with reshaping a matrix variable

reshape

Hello friends,
I have drawn to give better understanding of problem and also detailely explained below. If any one of you know possible solution that I missed, please feel free to let me know and if I lissed anything please feel fre to ask me.
Problem Definition:
I had a variable named Interpreted_power_1st_column = 105120 X 1 ;
  • This is the power availablitiy data at a location collected at every 5 mins interval for whole year.( 8760*12=105120) (there are 12 5 mins intervals in 1 hour ,and 8760 hours in 365 days)
  • I want the data to be avaerged to 1 hour interval, so I used reshape function in matlab( code below) to sum the 12 consequtive data points multiply by 5 and then divide the whole summation by 60….this is actually good way to get average data for 1 hour interval.
hourly_wind_energy1=zeros(8750,1); 
hourly_wind_energy1=((sum(reshape(Interpreted_power*5,12,8760)))/60); %Hourly Wind energy generated from intepretation of power curve KW-hr
hourly_wind_energy1=hourly_wind_energy1';%%Hourly Wind energy generated from intepretation of power curve KW-hr
Now I have to do the same but Interpreted_power = 105120 X 5 (5 columns)
I have be trying various ways like for loops but couldnot achieve my final result.
Possible solution 1 : any experts who are well aware of reshape function help me with a possible way to do the process I have done in problem definityin for an variable with several columns (for now 105120 X 5, 5 columns)
Possible solution 2:
  • to create 5 different variables (Interpreted_power_1st_column, Interpreted_power_2nd_column, Interpreted_power_3rd_column, Interpreted_power_4th_column, Interpreted_power_5th_column)
  • Interpreted_power_1st_column has 1st column of Interpreted_power = 105120 X 5
  • Interpreted_power_2nd_column has 2nd column of Interpreted_power = 105120 X 5
  • Interpreted_power_3rd_column has 3rd column of Interpreted_power = 105120 X 5
  • Interpreted_power_4th_column has 4th column of Interpreted_power = 105120 X 5
  • Interpreted_power_5th_column has 5th column of Interpreted_power = 105120 X 5
Now follow the same procedure used in Problem definition ( Use reshape function 5 times for 5 of these variables, then combine all the results into single variable with 8760 X 5 )
Problem with solution 2 : I am having trouble creating individual column variables,
Interpreted_power_1st_column=Interpreted_power(1:end);
Interpreted_power_1st_column=Interpreted_power_1st_column'; %% this is giving 1st column elements
Interpreted_power_2st_column=Interpreted_power(2:end);
Interpreted_power_2st_column=Interpreted_power_2st_column'; %% but all below are not exactly the required column elements 
Interpreted_power_3st_column=Interpreted_power(3:end);
Interpreted_power_3st_column=Interpreted_power_3st_column';
Interpreted_power_4st_column=Interpreted_power(4:end);
Interpreted_power_4st_column=Interpreted_power_4st_column';
Interpreted_power_5st_column=Interpreted_power(5:end);
Interpreted_power_5st_column=Interpreted_power_5st_column';
Thanks in advance

Best Answer

Hi Venkat,
For the problem with solution 2, following code can be used to extract individual column variables from ‘Interpreted_power’:
Interpreted_power_1st_column=Interpreted_power(:,1);
Interpreted_power_2st_column=Interpreted_power(:,2);
Interpreted_power_3st_column=Interpreted_power(:,3);
Interpreted_power_4st_column=Interpreted_power(:,4);
Interpreted_power_5st_column=Interpreted_power(:,5);
For more details, refer following documentation link on how to index a particular row/column:https://www.mathworks.com/help/matlab/math/array-indexing.html?searchHighlight=indexing&s_tid=doc_srchtitle
However, a more efficient approach would be writing a ‘for’ loop to traverse through all the columns of the variable ‘Interpreted_power’ and calculate ‘hourly_wind_energy’using the code below,
Interpreted_power = ones(105120,5); % put your interpreted power matrix here
hourly_wind_energy = ones(8760,5);  % Dummy variable pre-allocation
for i=1:5
    temp_interp = Interpreted_power(:,i);
    temp_hourly =((sum(reshape(temp_interp*5,12,8760)))/60);
    hourly_wind_energy(:,i) = temp_hourly';
end
HTH!
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