I'm interested in making a plot that has a category axis (e.g. set(gca,'YTickLabel', {'A', 'B', 'C'});)
However, I don't know the number of categories ahead of time. In fact, the categories are a vector of nonconsecutive numbers that I nevertheless want to plot consecutively as categories.
E.g. Vector = [5 7 9 2 6]
where Vector is a vector of integers and can be of any size.
I want to make an image() of a 2d matrix, where the Y axis has these integers applied to it as labels or categories for each tick. How can I do that?
I was able to figure it out, here is an example:
ydata=[5 7 9 2 6];
Z=rand(size(ydata,2),10); %random numbers where Y dimension is size of ydata
figure
imagesc(Z) %Make the image of Z
set(gca,'YTick',1:1:size(ydata,2)); % Set only ONE tick
% mark for each value of ydata
set(gca,'YTickLabel', ydata); %Label the tick marks with the values in ydata.
Related
Let
input = [0 0 0 5 5 7 8 8];
I now want to transform this vector into the form
output = [3 3 3 3 5 5 6 8];
Which basically is a stairs plot.
Explanation
The input vector is used to plot data points along the x-axis. The y-axis is thereby provided by 1:length(input). So the resulting plot shows the cumulative number of datapoints along the y-axis and the time of occurrence along the x-axis.
I now want to fit a model against my dataset. Therefor I need a vector that provides the correct value for a certain time (x-value).
The desired output vector basically is the result of a stairs plot. I am looking for an efficient way to generate the desired vector in matlab. The result of
[x, y] = stairs(input, 1:length(input));
did not bring me any closer.
It can be done with bsfxun as follows:
x = [0 0 0 5 5 7 8 8];
y = sum(bsxfun(#le, x(:), min(x):max(x)), 1);
This counts, for each element in 1:numel(x), how many elements of x are less than or equal to that.
I have some observational data that is relatively complete, but contains some NaN values, in an matrix in matlab and I want to interpolate them to a more evenly spaced grid using interp2
So, to keep things simple lets say I have one complete (no NaN values) matrix, and one that looks something like:
A = [ 1 2 3 4;
2 3 2 NaN;
0 2 3 4;
0 NaN 4 5 ]
with B and C being complete matrices, interp2 won't accept an input matrix with NaN values. So if I do something like this:
[AI,BI] = meshgrid(a,b) %# matrices to interpolate data to, arbitrary
CI = interp2(A,B,C,AI,BI) %# interpolation, A has NaN values
I get an error:
Error using griddedInterpolant
The coordinates of the input points must be finite values; Inf and NaN are not permitted.
Can anyone suggest either a solution, or reasonable work around that doesn't obstruct my data?
Sorry the quick fix I gave in comment does not work directly for 2D data (it does work that simply with interp1 though, if you ever need it).
For gridded data, if you have NaNs in your grid then you do not have a uniform grid and you cannot use interp2 directly. In this case you have to use griddata first, to re-interpolate your data over a uniform grid (patch the holes basically).
(1) Let's show an example inspired from the Matlab doc:
%% // define a surface
[A,B] = meshgrid(-3:0.25:3);
C = peaks(A,B);
%// poke some holes in it (in every coordinate set)
A(15,3:8) = NaN ;
B(14:18,13) = NaN ;
C(8,16:21) = NaN ;
(2) Now let's fix your data on a clean grid:
%// identify indices valid for the 3 matrix
idxgood=~(isnan(A) | isnan(B) | isnan(C));
%// define a "uniform" grid without holes (same boundaries and sampling than original grid)
[AI,BI] = meshgrid(-3:0.25:3) ;
%// re-interpolate scattered data (only valid indices) over the "uniform" grid
CI = griddata( A(idxgood),B(idxgood),C(idxgood), AI, BI ) ;
(3) Once your grid is uniform, you can then use interp2 if you want to mesh on a finer grid for example:
[XI,YI] = meshgrid(-3:0.1:3) ; %// create finer grid
ZI = interp2( AI,BI,CI,XI,YI ) ; %// re-interpolate
However, note that if this is all what you wanted to do, you could also use griddata only, and do everything in one step:
%// identify indices valid for the 3 matrix
idxgood=~(isnan(A) | isnan(B) | isnan(C));
%// define a "uniform" grid without holes (finer grid than original grid)
[XI,YI] = meshgrid(-3:0.1:3) ;
%// re-interpolate scattered data (only valid indices) over the "uniform" grid
ZI = griddata( A(idxgood),B(idxgood),C(idxgood), XI, YI ) ;
This produces the exact same grid and data than we obtained on step (3) above.
Last note: In case your NaNs are on the border of your domain, by default these functions cannot "interpolate" values for these border. To force them to do so, look at the extrapolation options of these functions, or simply interpolate on a slightly smaller grid which doesn't have NaN on the border.
I'm using the MATLAB plot feature to compare two vectors. I would like my X axis to represent 1 through 7, and then 14, 21, and then a category at the end for points with undetermined X values..(I'm also not sure how to represent these numberless point (they have Y values, just no X values) I could assign a large number outside any of my X values (1000) to these points, do the 1-7,14,21,1000 and then change the 1000 label to my 'string for un-numbered points'. ??
Here is a way to do it based on the example by The Mathworks here.
The trick is to create 2 x axis with different ranges and make one of them transparent. You can then play around with its properties. I modified a bit their code but kept most of their comments because they explain well the steps.
For the demo I used scatter to represent the points and colored the "good" points in red and the other point (here only 1) in green. You can customize all this of course. For instance I used a value of 100 and not 1000 for the x value of the 2nd axes, but I'll let you figure out how to modify it all to change the output as you wish.
clear
clc
close all
%// Create axes 1 and get its position
hAxes1 = axes;
axes_position = get(hAxes1, 'Position');
%// Create axes 2 and place it at the same position than axes 1
hAxes2 = axes('Position', axes_position);
%// Your data go here.
x = [1 7 14 21 100];
y = rand(1, length(x));
%// Plot the two sections of data on different axes objects
hPlot1 = scatter(hAxes1, x(1:4), y(1:4),40,'r','filled');
hold on
hPlot2 = scatter(hAxes2, x(end), y(end),40,'g','filled');
%// Link the y axis limits and fontsize property of the axes objects
linkaxes([hAxes1 hAxes2], 'y');
linkprop([hAxes1 hAxes2], 'FontSize');
%// Set the x range limits and tick mark positions of the first axes object
set(hAxes1, 'XLim', [1 25], ...
'XTick', [1 7 14 21])
%// Set the x range limits and tick mark positions for the second axes object.
%// Also set the background color to 'none', which makes the background
%// transparent.Add the label for the "super points".
set(hAxes2, 'Color', 'none', ...
'YTickLabel', [], ...
'XLim', [95 100], ...
'XTick', 100,'XTickLabel',{'Super Points'})
And the output:
EDIT
If you wish to add a fit line, I suggest adding a 3rd axes at the same position than the other 2, make it transparent and remove its X- and Y-ticks.
i.e. Add something like this:
hAxes3 = axes('Position', axes_position,'Color','none','YTick',[],'XTick',[]);
And in the call to polyfit/polyval, in my example you want to get only the first 4 elements (i.e. the red ones).
Hence:
p = polyfit(x(1:4),y(1:4),1);
y_poly = polyval(p,x(1:4));
And then plot the line on hAxes3:
hPlot3 = plot(x(1:4),y_poly)
Output:
I have a problem with MATLAB bar3 plots: Here is what I have:
m x n Array Values containing values of a measurement.
Another m x n Array Angles Represents the angle at which a value was measured (e.g. the 3rd value was measured at an angle of 90°). The angular values for each measurement value are stored in another variable.
I need a range for my x-axis from -180° to +180°. This alone is no problem. But how do I hand over my measurement values? I have to somehow link them to the angular values. So that each value in Values is somehow linked to it's angular value in Angles. For my y-axis, I can simply count from 0 to the amount of rows of my Values Array.
EXAMPLE:
Valueslooks like:
3 5 6
2 1 7
5 8 2
Angles looks like:
37° 38° 39°
36° 37° 38°
34° 35° 36°
Values(1,1) = 3 was measured at Angles(1,1) = 37° for example.
At each angle, the number of bars varies depending on how many measurements exist for that angle. bar3 needs a matrix input. In order to build a matrix, missing values are filled with NaN.
Warning: NaNs are usually ignored by plotting commands, but bar3 apparently breaks this convention. It seems to replace NaNs by zeros! So at missing values you'll get a zero-height bar (instead of no bar at all).
[uAngles, ~, uAngleLabels] = unique(Angles); %// get unique values and
%// corresponding labels
valuesPerAngle = accumarray(uAngleLabels(:), Values(:), [], #(v) {v});
%// cell array where each cell contains all values corresponding to an angle
N = max(cellfun(#numel, valuesPerAngle));
valuesPerAngle = cellfun(#(c) {[c; NaN(N-numel(c),1)]}, valuesPerAngle);
%// fill with NaNs to make all cells of equal lenght, so that they can be
%// concatenated into a matrix
valuesPerAngle = cat(2, valuesPerAngle{:}); %// matrix of values for each angle,
%// filled with NaNs where needed
bar3(uAngles, valuesPerAngle.'); %'// finally, the matrix can be plotted
ylabel('Angles')
xlabel('Measurement')
With your example Values and Angles this gives:
I have a Nx62 matrix with N 62-D vectors and a NX1 vector with the labels for the vectors. I am trying to plot these vectors with their labels because I want to see the behavior of these classes when plotted in a 62-dimensional space. The vectors belong to three classes according to the labels of a NX1 vector cited before.
How to to that in matlab? when i do plot(vector,classes) the result is very weird to analyse, how to put labels in the graph?
The code i am using to get the labels, vectors and plotting is the following:
%labels is a vector with labels, vectors is a matrix where each line is a vector
[labels,vectors]=libsvmread('features-im1.txt');
when I plot a three dimensional vector is simple
a=[1,2,3]
plot(a)
and then I get the result
but now i have a set of vectors and a set of labels, and i want to see the distribution of them, i want to plot each of these labels but also want to identify their classes. How to do that in matlab?
EDIT: This code is almost working. The problem is the fact that for each vector and class the plot will assign a color. I just want three colors and three labels, one per class.
[class,vector]=libsvmread('features-im1.txt');
%the plot doesn't allow negative and 0 values in the label
class=class+2;
labels = {'class -1','class 0','class 1'};
h = plot(vector);
legend(h,labels{class})
If I understand correctly, this does what you want:
N = 5;
classes = [1 2 3 1 2]; % class of each vector. Size N x 1
colors = {'r', 'g', 'b'}; % you can also define them numerically
matrix = rand(N,62); % example data. Size N x 62
labels = {'class 1','class 2','class 3'}; % class names. Size max(classes) x 1
h = plot(matrix.');
h_first = NaN(1,3); % initialization
for k = 1:max(classes)
ind = find(classes==k);
set(h(ind), 'color', colors{k}) % setting color to all plots of a given class
h_first(k) = h(ind(1)); % remember a handle of each color (for legend)
end
legend(h_first,labels)