By the way, here is a more succinct version, which uses readtable instead of xlsread (which is no longer recommended) and uses arrays (cell arrays, tables) instead of sequences of numbered variables (x1, x2, x3, ...):
sheet_names = sheetnames('DSC03765.xlsx');
N = numel(sheet_names);
C = cell(1,N);
for ii = 1:N
% read sheet
T = readtable('DSC03765.xlsx','Sheet',ii);
% rename table variables
T = renamevars(T,1:width(T),{'x','y','foo','bar','errorx','errory'});
% calculate magnitude
T.magnitude = sqrt(T.errorx.^2+T.errory.^2);
% store table in cell array
C{ii} = T;
end
% concatenate values of magnitude in one array
magnitude_total = vertcat(C{:}).magnitude;
% calculate min and max magnitude
mag_res = 0.05;
magnitudelim = [ ...
floor(min(magnitude_total)/mag_res) ...
ceil(max(magnitude_total)/mag_res) ...
]*mag_res;
% define a color map
n_colors = 4;
cmap = jet(n_colors);
% calculate the magnitude thresholds
mthresholds = linspace(magnitudelim(1),magnitudelim(2),n_colors+1);
nm = [570 525 850 490 550];
common_scale_factor = 50;
for ii = 1:numel(C)
plot_image(C{ii}.x, C{ii}.y, common_scale_factor*C{ii}.errorx, common_scale_factor*C{ii}.errory, ...
C{ii}.magnitude, mthresholds, cmap, magnitudelim, n_colors, nm(ii));
end
% plot function
function plot_image(x, y, errorx, errory, magnitude, mthresholds, cmap, magnitudelim, n_colors, nm)
figure
hold on
% for each color, find the indicies of the magnitudes at this color level
for ii = 1:n_colors
idx = magnitude >= mthresholds(ii) & magnitude < mthresholds(ii+1);
% generate an arrow of the corresponding color
quiver(x(idx), y(idx), errorx(idx), errory(idx), 'off', 'Color', cmap(ii,:));
end
% set up the colorbar
colormap(cmap);
colorbar();
caxis(magnitudelim);
xlim([0 2836])
ylim([0 2778])
title(sprintf('%d nm',nm));
hold off
end
