Why does the following function produce error (Index in position 2 exceeds array bounds)?

Question

Priyank Goel 2021-7-10

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/876058-why-does-the-following-function-produce-error-index-in-position-2-exceeds-array-bounds

编辑： Priyank Goel 2021-7-12

在 MATLAB Online 中打开

Why does the following function produce error-

Index in position 2 exceeds array bounds.

Error in POD_DMD (line 47)

imagesc(reshape(Phi(1:r*c,mode),r,c));axis

image;set(gca,'Ydir','Normal')

close all
figure('name','POD')
subplot(figs,1,1)
imagesc(reshape(Phi(1:r*c,mode),r,c));axis image;set(gca,'Ydir','Normal')
title(['\Phi',sprintf('_%i (u-component)',mode)])
subplot(figs,1,2-d)
if com == 2 
    imagesc(reshape(Phi(r*c+1:end,mode),r,c));axis image;set(gca,'Ydir','Normal')
    title(['\Phi',sprintf('_%i (v-component)',mode)]);
end

Please suggest possible solution.

Thanks!

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Priyank Goel 2021-7-10

在 MATLAB Online 中打开

Thanks for your responce,

This is the complete code.

clear all;
clc;
%%%%%%%%%%%%%%%%%%  INPUT  %%%%%%%%%%%%%%%%%%%%%
freq = 5; %Hz; aquisition frequency
example = '4_68_image'; % input case 
mode=2; % which mode to plot and extract DMD from
%%%%%%%%%%%%%%%%%%% SCRIPT %%%%%%%%%%%%%%%%%%%%%
% Import the images from folder. The images are extracted from the Schlieren 
% video for wedge_4_68 at Mach 2.5.  
data = [];
% if strcmp(example,'image')
    directory = '4_68_image';
    count = 1;
    while exist(sprintf('%s/scene_%0.4d.bmp',directory,count)) ~= 0
        data(:,:,count) = imread(sprintf('%s/scene_%0.4d.bmp',directory,count));
        count = count +1;
    end
    r = size(data,1); c = size(data,2);
    % Transform the data into column vectors.
    data=reshape(data,r*c,size(data,3)); 
% end    
% if strcmp(example,'groynes') 
%     directory = '4_68_image';
%     count = 1;
%     while exist(sprintf('%s/scene_%0.4d.bmp',directory,count)) ~= 0
%         load(sprintf('%s/scene_%0.4d.bmp',directory,count))
%         data_u(:,:,count) = u;
%         data_v(:,:,count) = v;
%         count = count +1;
%     end
%     r = size(data_u,1); c = size(data_u,2);
%     % Transform the data into column vectors.
%     data=[reshape(data_u,r*c,size(data_u,3));reshape(data_v,r*c,size(data_v,3))];
%%%%%%%%%%%%%%%%%%% POD %%%%%%%%%%%%%%%%%%%%%%
% Perform the POD - this is mean subtracted for POD not for DMD
[Phi ,~, C]=svd(data-repmat(mean(data,2),[1 size(data,2)]),'econ');
% Plot the figures
figs = 3;com=1;d=1;
close all
figure('name','POD')
subplot(figs,1,1)
imagesc(reshape(Phi(1:r*c,mode),r,c));axis image;set(gca,'Ydir','Normal')
title(['\Phi',sprintf('_%i (u-component)',mode)])
subplot(figs,1,2-d)
if com == 2 
    imagesc(reshape(Phi(r*c+1:end,mode),r,c));axis image;set(gca,'Ydir','Normal')
    title(['\Phi',sprintf('_%i (v-component)',mode)]);
end
subplot(figs,1,3-d)
plot(C(:,mode))
title(sprintf('C_%i',mode))
subplot(figs,1,4-d)
[px, fx]=pwelch(C(:,mode),round(0.9*size(data,2)),round(0.8*size(data,2)),...
    2^12,freq);
plot(fx,px);
title(sprintf('P(C_%i)',mode))
set(figure(1),'position',[246    66   370   732])
waitfor(msgbox('Please select the peak of the POD coefficient spectra (bottom image) you would like to extract'))
[x, y]=ginput(1);
[locs, vals]=findpeaks(px); 
[v, l]=min(abs(fx(vals)-x)); 
hold on
plot(fx(vals(l)),locs(l),'ro')

Priyank Goel 2021-7-12

Dear Walter,

I was able to read directory

K>> ls(directory)

. scene_0016.bmp scene_0033.bmp scene_0050.bmp

.. scene_0017.bmp scene_0034.bmp scene_0051.bmp

scene_0001.bmp scene_0018.bmp scene_0035.bmp scene_0052.bmp

scene_0002.bmp scene_0019.bmp scene_0036.bmp scene_0053.bmp

scene_0003.bmp scene_0020.bmp scene_0037.bmp scene_0054.bmp

scene_0004.bmp scene_0021.bmp scene_0038.bmp scene_0055.bmp

scene_0005.bmp scene_0022.bmp scene_0039.bmp scene_0056.bmp

scene_0006.bmp scene_0023.bmp scene_0040.bmp scene_0057.bmp

scene_0007.bmp scene_0024.bmp scene_0041.bmp scene_0058.bmp

scene_0008.bmp scene_0025.bmp scene_0042.bmp scene_0059.bmp

scene_0009.bmp scene_0026.bmp scene_0043.bmp scene_0060.bmp

scene_0010.bmp scene_0027.bmp scene_0044.bmp scene_0061.bmp

scene_0011.bmp scene_0028.bmp scene_0045.bmp scene_0062.bmp

scene_0012.bmp scene_0029.bmp scene_0046.bmp

scene_0013.bmp scene_0030.bmp scene_0047.bmp

scene_0014.bmp scene_0031.bmp scene_0048.bmp

scene_0015.bmp scene_0032.bmp scene_0049.bmp

But now the issue is: Unable to perform assignment because the indices on the left side are not

compatible with the size of the right side.

Error in POD_DMD (line 17)

data(:,:,count) =

imread(sprintf('%s/scene_%04d.bmp',directory,count));

Please help as I am not experienced in Matlab.

Walter Roberson 2021-7-12

在 MATLAB Online 中打开

        data(:,:,count) =
rgb2gray(imread(sprintf('%s/scene_%04d.bmp',directory,count))) ;

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Answer 1

Priyank Goel 2021-7-12

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/876058-why-does-the-following-function-produce-error-index-in-position-2-exceeds-array-bounds#answer_745138

编辑：Priyank Goel 2021-7-12

Thanks a lot Walter, now I am able to run it.

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Why does the following function produce error (Index in position 2 exceeds array bounds)?

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Why does the following function produce error (Index in position 2 exceeds array bounds)?

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