Using index data to fill a matrix
24 views (last 30 days)
Show older comments
I have a matrix which I have extracted from an Excel file that contains [row_location, column_location, data]. The row and column are non conituous, so the matrix looks like this:
ExtractedData =
[8] [93] [0.1981]
[8] [94] [0.2209]
[8] [95] [0.2276]
[8] [96] [0.2276]
[9] [49] [0.2773]
[9] [50] [0.3941]
[9] [51] [0.3256]
[9] [52] [0.3135]
[9] [53] [0.2343]
[9] [54] [0.3337]
I know how big the full matrix would be from
MaxRow = max(ExtractedData(:, 1))
MaxCol = max(ExtractedData(:, 2))
So I create a NaN matrix of the size
DataToPlot = NaN(MaxRow MaxCol)
& then I would like to populate the correct entry in the DataToPlot matrix with the data from the spreadsheet i.e.
DataToPlot(8, 93) = 0.1981
DataToPlot(8, 94) = 0.2209
DataToPlot(8, 95) = 0.2276
etc
I can see that I want to use a loop to step through the ExtractedData one row at a time, but then I'm unsure of how to extract & use the index data to populate the correct location with the data.
The end goal is to generate a surface plot of the data so if there are any shortcuts or 'best practice' ways of going from extacted data to surface plot I'd appreciate a steer in the right direction.
0 Comments
Accepted Answer
Jan
on 15 Feb 2019
Edited: Jan
on 15 Feb 2019
This works with a loop easily:
D = ExtractedData; % Easier to read...
MaxRow = max(D(:, 1));
MaxCol = max(D(:, 2));
ToPlot = NaN(MaxRow, MaxCol);
for k = 1:size(D, 1)
ToPlot(D(k, 1), D(k, 2)) = D(k, 3);
end
MaxSize = max(D(:, 1:2), [], 1); % Get size as vector
ToPlot = NaN(MaxSize);
index = sub2ind(MaxSize, D(:, 1), D(:, 2)); % [EDITED, Typo: D(:,1) -> D(:,2)]
ToPlot(index) = D(:, 3);
3 Comments
Jan
on 15 Feb 2019
You are welcome. I've fixed the typo now.
Please use the section from comments to post a comment.
More Answers (0)
See Also
Categories
Find more on Resizing and Reshaping Matrices in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!