Remove 2D array elements outside of a range

Question

KCE 2022-3-30

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1684739-remove-2d-array-elements-outside-of-a-range

评论： Voss 2022-5-28

Hi,

I am attempting to remove array elements that fall outside of specified ranges. The array I am working with is 199x199 (wmax), and there are subsequent 199x199 arrays that contain both longitudes (x_pts) and latitudes (y_pts).

Essentially I want to create a smaller array that only includes data within 2 given latitudes and longitudes. Whenever I try this, it returns an N x 1 array, but I am hoping for a 2D array to be returned.

wmax(x_pts>-103&x_pts<-100&y_pts>34.75&y_pts<36.5;

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Answer 1

Voss 2022-3-30

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https://ww2.mathworks.cn/matlabcentral/answers/1684739-remove-2d-array-elements-outside-of-a-range#answer_930834

在 MATLAB Online 中打开

Try one of these two things, depending on whether x_pts corresponds to the rows or columns of wmax:

% if x_pts corresponds to the rows of wmax and y_pts is the columns:
wmax(x_pts>-103 & x_pts<-100, y_pts>34.75 & y_pts<36.5);
% if x_pts corresponds to the columns of wmax and y_pts is the rows:
wmax(y_pts>34.75 & y_pts<36.5, x_pts>-103 & x_pts<-100);

Example:

x_pts = 1:10;
y_pts = 102:109;
% x_pts goes with rows, y_pts goes with columns, in this case
wmax = randn(numel(x_pts),numel(y_pts))
wmax = 10×8
    0.1245   -1.1668   -0.0475    0.5001   -0.2800    1.3163    0.6479    1.2807
    1.5173    0.6925   -1.1350    0.5612    2.2336    0.8672    0.3282   -0.2573
   -0.6798    1.2087    1.1384    1.8517    1.2552   -0.5807   -0.5476    1.7234
    1.1392   -0.7541    0.5278   -0.1743   -0.3634   -0.0129   -1.1077   -0.0505
   -0.9966    0.0368    0.0110   -1.2554    0.4684   -2.0030    2.2644   -0.1099
    0.0899   -0.0061   -1.2089   -0.4280   -0.8558    1.5466   -0.7792    0.3896
   -0.6317    0.0086    0.9400    0.1565   -0.5707    0.1088   -0.5228   -1.4621
    0.1477    0.7005    0.1280    0.1691   -0.8256    0.9573    0.7240    1.3552
    0.5469   -0.5682    0.0907    1.2396   -1.5674   -0.7999   -1.1673    0.6018
    0.7427   -0.5076    1.3764   -1.8479   -0.4785    0.0112   -1.8359    0.3773
wmax(x_pts>3 & x_pts<7, y_pts>105 & y_pts<108)
ans = 3×2
   -0.3634   -0.0129
    0.4684   -2.0030
   -0.8558    1.5466

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KCE 2022-5-27

I have tried this along with multiple combinations, and they all seem to return a 1D answer.

Voss 2022-5-28

在 MATLAB Online 中打开

Make sure you have the comma where you had an & before:

wmax(x_pts>-103 & x_pts<-100, y_pts>34.75 & y_pts<36.5);
%                           ^

If that's not the problem, then can you demonstrate it here, with an example? Either construct a small matrix along with two vectors to use for indexing into the matrix, or save your variables to a mat file and upload it (with the paperclip button).

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