I have a matrix for example A=rand(60,60). I want to set the x-axis and y-axis value with step size: 1:2:119 in 3d bar (matlab bar3). I already tried to make it but it doesn't work for large matrix. Note, y-axis is perfect but x-axis is not, it shows from 1 to 60. For example:
Z = rand(60,60);[r,c] = size(Z);
Y = 1:2:119; % y-axis value
X = 1:2:119; % x-axis value
bar3(Y,Z); set(gca,'XTick', X)
See: xlim and ylim
Z = rand(60,60);
[r,c] = size(Z);
Y = 1:2:119; % y-axis value
X = 1:2:119; % x-axis value
bar3(Y,Z);
xlim([X(1), X(end)]);
set(gca,'XTick', X)
ylim([Y(1), Y(end)]);
set(gca,'YTick', Y)
The ticks are super crowded but I'm just going with what you specified in your example.
Related
How can I build my own function in Matlab that does the same work as the Matlab built-in function 'semilogx'?
Example: in this example both fig.1 and fig.2 plot x as a log scale but the values on the x-axis of fig.1 are not correct. So the question is "how can I make the values in fig.1 same as the values in fig.2 without using semilogx?"
x = 0:1000;
y = 2*x;
figure(1), plot(log10(x), y)
figure(2), semilogx(x,y)
I guess in my example above: in Fig.1 x limit is between [0,3] and in Fig.2 x limit is between [0,1000]. What I understand is that x limit should be [0:1000] but when we use log scale this would change to [0,3] so the semilogx function only maps the [0,3] limit to [0,1000]
Basically you have to reconstruct the x-axis tick mark locations and the corresponding tick labels on a log-scaled grid:
% Some data
x = 1:1000;
y = cumsum(rand(size(x)));
% For comparison
subplot(311); plot(log10(x), y)
subplot(312); semilogx(x,y)
% Simulated semilogx plot
subplot(313); plot(log10(x), y)
ax = gca; % Get a handle to the axis for tick modifications
% Compute tick mark locations in log10 scale
logxmax = ceil(log10(x(end)));
ticks = log10(1:9);
ticks = ticks' + (0:logxmax-1);
ticks = [ticks(:); logxmax];
% Set tick marks and labels
ax.XTick = ticks;
ax.XLim = [0 logxmax];
% Reset tick labels
ax.XTickLabel(:) = ''; % clear all tick labels
I = 1+9*(0:logxmax); % Tick labels for 10^n locations
S = arrayfun(#(x)'10^{'+string(x)+'}', (0:logxmax), 'UniformOutput', false);
ax.XTickLabel(I) = S;
I want to change the y axis of the histogram to show percentages ranging from 0 to 1. this is what I've tried, but it doesn't seem to be working.
myTolerance=1e-12; % in erg units.
nbins=50;
for j=1:ntM/100:ntM
H = histfit(Wkinet(abs(Wkinet(:,j))>myTolerance, j) * erg2eV, nbins);
%Select from column j all rows in column j whose absolute values are
%greater than the tolerance.
H(1).delete; %%Remove bins, only keep the fit.
set(gca, 'YScale', 'log');
set(gca, 'XScale', 'log'); % Make logarithmic X
yt = get(gca, 'YTick');
set(gca, 'YTick', yt, 'YTickLabel',
yt/numel(Wkinet(abs(Wkinet(:,j))>myTolerance)))
pause;
end
This is what is currently looks like:
This is what I want:
Just to simplify the discussion below, the line
H = histfit(Wkinet(abs(Wkinet(:,j))>myTolerance, j) * erg2eV, nbins);
is equivalent to
data = Wkinet(abs(Wkinet(:,j))>myTolerance, j) * erg2eV;
H = histfit(data, nbins);
This means below we'll assume data is a vector.
histfit computes and plots a histogram though histogram, then fits a function to it through fitdist. Since you don't want to plot the histogram itself, just stick to fitdist:
pd = fitdist(data,'Normal'); % this is the default distribution used in `histfit`, is it correct?
x = linspace(min(data),max(data),200); % 200 points in the graph, you might want to change this?
y = pdf(pd,x);
plot(x,y);
Now it's simple to normalize the plot however we want. For example set the first element to 1:
pd = fitdist(data,'Normal');
x = linspace(min(data),max(data),200);
y = pdf(pd,x);
y = y/y(1); % <<< Normalize
plot(x,y);
You can set limits on your y-axis using
ylim([1e-3 1]) %lower limit is nonzero since it's plotted on log scale
or
set(gca, 'ylim', [1e-3 1])
I am trying to reproduce the Dirac Delta function:
my code:
x = -30:1:30;
y = zeros(1,numel(x)); %sets all values initially to zero
y(x==0)= inf; % the point corresponding to x=0 is set to inf
plot(x,y,'d')
axis([-40 40 0 inf])
My code produces:
You can do this with stem, specifying its 'Marker' as an up arrow...
% Open figure
figure;
% Blue stem plot at x=0, to y=75. Marker style is up arrow
stem(0, 75,'color','b','linewidth',2,'marker','^')
% Add infinity label at x=0, y = 82 = 75 + fontsize/2, where we plotted up to 75
text(0,82,'∞','FontSize',14)
% Set axes limits
xlim([-40,40])
ylim([0,90])
You can see the output plot here, but see the edit below for an improved version.
Note, of course you should choose a y value which is large relative to any other data on the plot. In this example I chose 75 to roughly match your desired example plot. MATLAB can't plot a value at inf because, well, where does infinity sit on the y axis?
Edit: You can indicate the y-axis is broken with additional '≈' characters as suggested by Marco in the comments. Combining xlim and ylim into one axis call, and changing the y-axis ticks to help indicate the axis break, we get this result:
stem(0, 80,'color','b','linewidth',2,'marker','^')
text([-42,0,38], [80,87,80], {'≈','∞','≈'}, 'Fontsize', 14)
axis([-40, 40, 0, 100])
yticks(0:20:60)
To show infinity, you should not set y to infinity. To do this, you can set y to a large value proportional to the axis values. For example if axis would be like [min_x max_x min_y max_y], you can set y(x==0) = max_y*10.
In your case you will have:
x = -30:1:30; min_x = min(x) - 10; max_x = max(x) + 10;
y = zeros(1,numel(x));
% compute values of y here
% ...
min_y = min(y) - 10; max_y = max(y) + 10;
y(x==0)= 10 * max_y;
plot(x,y,'d');
axis([min_x max_x min_y max_y]);
Use the tick property in Matlab plot as described below
Solution posted below function to plot bar 3 with separate x, y values and separate width and height values
bar3(x,y,z,xWidth,yWidth)
We are currently working on a project that allow one to visualize the area under a 3d function, f(x,y). The purpose of this is to demonstrate how the bars cut a 3d surface. Indirectly to visualize the desired integral.
We wish to have the bars match up with the intervals of the surface grid.
Below is a rough demonstration of the idea.
bar3 only has input for the x-values bar3(x,z), where as surf has a input for both the x and y surf(x,y,z)
Unfortunately this is what we are getting. - this is because bar3 cant be in terms of x and y
CODE:
clc;
cla;
d=eval(get(handles.edtOuterUpperB,'string'));
c=eval(get(handles.edtOuterLowerB,'string'));
b=eval(get(handles.edtInnerUpperB,'string'));
a=eval(get(handles.edtInnerLowerB,'string'));
n=eval(get(handles.edtInnerInterval,'string'));
m=eval(get(handles.edtOuterInterval,'string'));
h=(b-a)/n;
k=(d-c)/m;
[x,y] = meshgrid(a:h:b, c:k:d);
f=eval(get(handles.edtFunc,'string'));
surf(x,y,f);
hold on
bar3(f,1);
If you look closely, you will see that the XData and YData are different from the mesh to the 3D bar plot. This is because your mesh uses "real" x and y values while the bar plot uses indexes for the x and y values.
To fix this, you will want to change one or the other. For your case, the easiest one to change is going to be the surface. You can actually just omit the x and y inputs and the indexed x and y values will be used instead by default when generating the surface.
surf(f);
From the documentation for surf:
surf(Z) creates a three-dimensional shaded surface from the z components in matrix Z, using x = 1:n and y = 1:m, where [m,n] = size(Z). The height, Z, is a single-valued function defined over a geometrically rectangular grid. Z specifies the color data, as well as surface height, so color is proportional to surface height.
Update
If you want to keep the non-indexed values on the x and y axes, you will want to convert the bar3 plot instead. Unfortunately, MATLAB provides a way to specify the x axis bot not the y axis. You can take one of two approaches.
Change the XData
You can get the XData property of the resulting bar objects and change them to the data you want.
x = a:h:b;
y = c:k:d;
%// Anonymous function to scale things for us
scaler = #(vals)x(1) + ((vals-1) * (x(end) - x(1)) / (numel(x) - 1));
%// Create the bar plot
bars = bar3(y, f);
%// Change the XData
xdata = get(bars, 'XData');
xdata = cellfun(scaler, xdata, 'uni', 0);
set(bars, {'XData'}, xdata);
set(gca, 'xtick', x)
%// Now plot the surface
surf(x,y,f);
And just to demonstrate what this does:
x = linspace(0.5, 1.5, 5);
y = linspace(2.5, 4.5, 4);
f = rand(4,5);
scaler = #(vals)x(1) + ((vals-1) * (x(end) - x(1)) / (numel(x) - 1));
bars = bar3(y, f);
set(bars, {'XData'}, cellfun(scaler, get(bars, 'XData'), 'uni', 0))
set(gca, 'xtick', x)
axis tight
Change the XTickLabels
Instead of changing the actual data, you could simply change the values that are displayed to be what you want them to be rather than the indexed values.
x = a:h:b;
y = c:k:d;
labels = arrayfun(#(x)sprintf('%.2f', x), x, 'uni', 0);
bar3(y, f);
set(gca, 'xtick', 1:numel(x), 'xticklabels', labels);
hold on
%// Make sure to use the INDEX values for the x variable
surf(1:numel(x), y, f);
We found a user contributed function scatterbar3, which does what we want, in a different way than what bar3 uses:
http://www.mathworks.com/matlabcentral/fileexchange/1420-scatterbar3
There was however a slight hiccup that we had to correct:
hold on
scatterbar3(x,y,f,h);
scatterbar3 does not have separate inputs for the width and height of the bars, thus large gaps occur when the intervals do not equal one another. Demonstrated below.
We thus edited the scatterbar3 function in order to take both the width and height of the bars as inputs:
Edited scatterbar3 function:
function scatterbar3(X,Y,Z,widthx,widthy)
[r,c]=size(Z);
for j=1:r,
for k=1:c,
if ~isnan(Z(j,k))
drawbar(X(j,k),Y(j,k),Z(j,k),widthx/2,widthy/2)
end
end
end
zlim=[min(Z(:)) max(Z(:))];
if zlim(1)>0,zlim(1)=0;end
if zlim(2)<0,zlim(2)=0;end
axis([min(X(:))-widthx max(X(:))+widthx min(Y(:))-widthy max(Y(:))+widthy zlim])
caxis([min(Z(:)) max(Z(:))])
function drawbar(x,y,z,widthx,widthy)
h(1)=patch([-widthx -widthx widthx widthx]+x,[-widthy widthy widthy -widthy]+y,[0 0 0 0],'b');
h(2)=patch(widthx.*[-1 -1 1 1]+x,widthy.*[-1 -1 -1 -1]+y,z.*[0 1 1 0],'b');
h(3)=patch(widthx.*[-1 -1 -1 -1]+x,widthy.*[-1 -1 1 1]+y,z.*[0 1 1 0],'b');
h(4)=patch([-widthx -widthx widthx widthx]+x,[-widthy widthy widthy -widthy]+y,[z z z z],'b');
h(5)=patch(widthx.*[-1 -1 1 1]+x,widthy.*[1 1 1 1]+y,z.*[0 1 1 0],'b');
h(6)=patch(widthx.*[1 1 1 1]+x,widthy.*[-1 -1 1 1]+y,z.*[0 1 1 0],'b');
set(h,'facecolor','flat','FaceVertexCData',z)
Finally the working solution in action:
hold on
scatterbar3(x,y,f,h,k);
It is necessary for me that plot a rectangular in MATLAB by contour. But when I plot this, the figure is like square and no rectangular.
In fact the length of X axis and Y axis are true, but figure is not rectangular.
How could I find a rectangular figure?
Once before I needed to plot a n eliptical by countour and it was like circle, by setting axes([xmin xmax ymin ymax]) this problem was solved but know this command do not work.
Here is my code u0,x,y are 3 vectors of length nx*ny. and nx and ny are the number of points in x axis and y axis.
figure
for i=1:ny
z(i,:)=u0((i-1)*nx+1:i*nx);
x1(i,:)=x((i-1)*nx+1:i*nx);
y1(i,:)=y((i-1)*nx+1:i*nx);
end;
cMap = [0.45 0.6 0.65;1 1 1]; % [green;yellow] on rgb-color
colormap(cMap);
axis equal
contourf(x1,y1,z,'LineColor','none')
colorbar
Let 's=0:0.1:0.2' and 'x=repmat(s,1,ny)' and 'd=0:0.1:1', 'y=repmat(d,1,nx)'
'u0=x+y'
I think the problem is the size of the vector you are using. Check out this example:
x = linspace(0,2,20);
y = linspace(0,1,10);
z = meshgrid(x,y);
contourf(x,y,z,20);
axis equal
it gives the following result:
Now if we check the sizes:
>> size(x)
ans =
1 20
>> size(y)
ans =
1 10
>> size(z)
ans =
10 20
if the size of x vector is equal to the size of the y vector it gives you a square obviously! in your case first check the size of x1, y1, z just before using the contourf an make sure that you are using axis equal after that.