MATLAB: Extracting data from a text for further analysis

MATLABtext file reader

Hi,

I am new to importing data from text files to MATLAB for data processing. I have experience doing this process from excel to MATLAB, however this seems a bit more tedius.

I have a text file which I need to extract the 1st line of numeral text (line 11) as the Y coordinate matrix, the second line of numerical text (line 12) as the X coordinate matrix and lines 3-7 (lines 13-17) as the Z coordinate Matrix. This data will then be plotted on a contour plot (code already completed and found below). I also need to extract the 1st line of text (line 3) to insert as the figure's title (a below).

Code:

%plotting MSI yacht 1
figure
contourf(N_X1,N_Y1,N_Z1,50,'edgecolor','none')
title(a);
colormap cool %map colour style
xlabel('Peak Period (t)');
ylabel('Heading (deg)');
c = colorbar('southoutside');
c.Label.String = ('MSI%');

Best Answer

textChar = fileread('example.txt'); 
textCell = strsplit(textChar,'\n')'; 
y = str2num(textCell{11}); 
x = str2num(textCell{12}); 
z = str2num([textCell{13:17}]); 
titleStr = textCell{3};
titleStr = strrep(titleStr, 'Graph Title - ', ''); %Remove Graph Title -

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MATLAB: Common color range for surface.m and surf.m for subplots

The first problem is quite simple. You just need to specify the limit of the color axis. If you set the same limits for all axes, then, value at the same level will have the same color. Try this code

[X,Y] = meshgrid(linspace(-1/2*pi,1/2*pi));
Z1 = cos(X).*cos(Y);
Z2 = 2*cos(X).*cos(Y);
% 2D figure

figure;
subplot(1,2,1);
surface(X,Y,Z1,'EdgeColor','flat','LineStyle','none','FaceColor','flat');
caxis([0 2]) % <---- this line



subplot(1,2,2);
surface(X,Y,Z2,'EdgeColor','flat','LineStyle','none','FaceColor','flat');
caxis([0 2]) % <---- this line
% 3D figure

figure;
subplot(1,2,1);
surf(X,Y,Z1,'EdgeColor','flat','LineStyle','none','FaceColor','flat');
caxis([0 2]) % <---- this line
subplot(1,2,2);
surf(X,Y,Z2,'EdgeColor','flat','LineStyle','none','FaceColor','flat');
caxis([0 2]) % <---- this line

The second problem is a bit complicated. You need to create your own colormap such that the color appears to be discrete. Try the following code. I divided the interval [0,2] into 5 portions. This code used random colors for each portion, you can define your own RGB colors equal to the number of portions.

[X,Y] = meshgrid(linspace(-1/2*pi,1/2*pi));
Z1 = cos(X).*cos(Y);
Z2 = 2*cos(X).*cos(Y);
% define the custom discrete colormap
color_edges = [0 0.4 0.8 1.2 1.6 2.0]; % 5 intervals
colors = rand(5,3); % define as many rgb colors as the number of intervals
resolution_colormap = 100;
t = linspace(min(color_edges), max(color_edges), resolution_colormap);
c_idx = discretize(t, color_edges);
c_map = colors(c_idx, :);
% 2D figure
figure;
subplot(1,2,1);
surface(X,Y,Z1,'EdgeColor','flat','LineStyle','none','FaceColor','flat');
colormap(c_map);
caxis([0 2])
subplot(1,2,2);
surface(X,Y,Z2,'EdgeColor','flat','LineStyle','none','FaceColor','flat');
colormap(c_map);
caxis([0 2])
% 3D figure
figure;
subplot(1,2,1);
surf(X,Y,Z1,'EdgeColor','flat','LineStyle','none','FaceColor','flat');
colormap(c_map);
caxis([0 2])
subplot(1,2,2);
surf(X,Y,Z2,'EdgeColor','flat','LineStyle','none','FaceColor','flat');
colormap(c_map);
caxis([0 2])

MATLAB: Center align multi-line title in latex format

Using Latex forces left-alignment of lines in cell array of strings . (This may have been changed in the newest versions of Matlab. I use 2014b.) I think you can get most (or all) the effects you need by using the standard Tex formatting, which will center both lines. Example:

str1 = sprintf('\\gamma = %3.1f',1.4);
str2 = sprintf('s_k=%d, a_k=%d',2,3)
figure;title({str1,str2});

Best Answer

Related Solutions

MATLAB: Common color range for surface.m and surf.m for subplots

MATLAB: Center align multi-line title in latex format

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