I can add 2 y-axis to a octave/matlab plot but when I try and add the x-axis at the bottom of the plot with xlabel('Frequency in Hz') it doesn't show up
[ax h1 h2]=plotyy(xx,yy,xx,yy2); %plot two y axes and 1 x-axis
axes(ax(1)); ylabel('Phase Angle in degrees');
axes(ax(2)); ylabel('Amplitude');
Anybody know how to fix this so the x-axis will also show up
I'm using octave 3.2.4 / matlab
Make sure to call xlabel() after referencing one of the specific axes on the plot. You just need to do it once, but because of the double axis, invoking x-label outside of a specific axis context won't work. The following works for me just fine in Octave 3.2.4.
xx = [1,2,3];
yy = [10,11,12];
yy2 = [-10,-11,-12];
[ax h1 h2]=plotyy(xx,yy,xx,yy2);
axes(ax(1)); xlabel('Frequency in Hz'); ylabel('Phase Angle in degrees');
axes(ax(2)); ylabel('Amplitude');
In order to add a label (either xlabel or ylabel) to certain axes you can also pass this axes reference as first argument of the command call. This way you will also guarantee that you are on the right context as #EMS pointed out.
xx = [1,2,3];
yy = [10,11,12];
yy2 = [-10,-11,-12];
[ax h1 h2]=plotyy(xx,yy,xx,yy2);
xlabel(ax(1),'Frequency in Hz'); ylabel(ax(1),'Phase Angle in degrees');
ylabel(ax(2),'Amplitude');
This is also better in terms of performance, as in case you call axes several times, you will see how everything slows considerably down.
Related
I need ideas to resize my axes to have a much more airy graph to better visualize and calculate the gain between the different curves.
I used the code : axis([0 6 1e-3 1e0]) or xlim([0 6]); ylim([1e-3 1e0])
I would like to have for example my curve with: xlim([0:0.2:6]) (just the idea, otherwise it's wrong on matlab).
Thank you!
If I understand what you want, you need more XTicks in the x limits mentioned. After you plot just:
set(gca,'XTick',0:0.2:6)
another way is to write:
h=plot(.... whatever you plot...
h.XTick=0:0.2:6
Logarithmic Plot:
To create the axes the function xticks() and yticks() can be used to set the intervals, start and endpoints. xticks() and yticks() essentially take vectors that define all the ticks on the scales/axes. Just in case you'd like to also edit the interval along the y-axis. This vector can be created by raising each element in the vector (-3,1:0) to be an exponent with a base of 10. Finally, setting gca (the current axis) to logarithmic will allow the vertical spacing between the ticks to be evenly distributed.
axis([0 6 1e-3 1e0]);
Start = 0; Interval = 0.2; End = 6;
X_Vector = (Start: Interval: End);
xticks(X_Vector);
Y_Vector = 10.^(-3: 1: 0);
yticks(Y_Vector);
set(gca, 'YScale', 'log');
title("Logarithmic Plot");
grid;
Ran using MATLAB R2019b
Question:
Write a function called point_cloud that takes one scalar as an input argument (the function does not have to check the format of the input) and has no output argument.
If it is called like this, point_cloud(100), then it plots 100 points. Each point has a random x coordinate and a random y coordinate, each of which is gotten by a call to randn, which uses a normal distribution with a standard deviation equal to 1. The range of the plot axes should be −5 to 5 in both the x and y dimensions. The grid should be turned off. The points should be plotted and displayed one at a time by calling plot with only one point specified and, following the call of plot, by a call of drawnow, which causes the point to be plotted immediately. The command hold on should be included so that all previous points are retained when a new point is plotted.
Figure 2.41 shows an example view of the plot after point_cloud(100000) has completed its point-by-point plotting on a Mac. (Note that on Windows the points are much larger. Also note that it takes a long time to plot this many points with drawnow. Finally, try zooming in the middle.)
Figure 2.41
My Code:
function point_cloud(N)
hold on
grid off
axis([-5,5,-5,5])
for ii = 1:N
plot(randn(ii));
drawnow;
end
I know this is wrong, but I'm not sure how to solve this problem. Can someone help?
Solved code:
function point_cloud(N)
figure
hold on
grid off
axis([-5,5,-5,5])
x = randn(N,1);
y = randn(N,1);
for ii = 1:N
plot(x(ii),y(ii),'b.');
drawnow;
end
You do not need the for loop at all. And drawing the plot each iteration is very time consuming. How about rather using the scatter function.
figure
hold on
grid off
axis([-5,5,-5,5])
x = randn(N,1);
y = randn(N,1);
scatter(x,y,'b.')
This will be a lot faster.
To add to the other answer, here is the code as a function, with the added functionality that the points are one pixel on Windows as well:
function point_cloud(N)
f = figure;
x = randn(N,1);
y = randn(N,1);
scatter(x,y,1/36,'b.');
f.GraphicsSmoothing = 'off';
grid off
axis([-5,5,-5,5])
axis equal
end
The size of the markers is set with the third parameter of scatter: 1/36. The graphics smoothing of the figure needs to be set to 'off' as well, to make sure that the pixels don't become blurry or lighter.
Here's a 3D version:
function point_cloud3D(N)
f = figure;
x = randn(N,1);
y = randn(N,1);
z = randn(N,1);
scatter3(x,y,z,1/36,'b.');
f.GraphicsSmoothing = 'off';
grid off
axis([-5,5,-5,5,-5,5])
axis square
view(3)
end
Is there a way to remove only the axis lines in the Matlab figure, without affecting ticks and tick labels.
I know that box toggles the upper and right axes lines and ticks and that works perfectly for me.
But my problem is that I want eliminate the bottom and left lines (only lines!) but keeping the ticks and tick labels.
Any tricks?
Yair Altman's Undocumented Matlab demonstrates a cleaner way to do this using the undocumented axes rulers:
plot(x,y);
ax1 = gca;
yruler = ax1.YRuler;
yruler.Axle.Visible = 'off';
xruler = ax1.XRuler;
xruler.Axle.Visible = 'off'; %// note you can do different formatting too such as xruler.Axle.LineWidth = 1.5;
A nice feature of this approach is that you can separately format the x and y axis lines.
Solution for Matlab versions prior to R2014b
You can introduce a new white bounding box and put it on top.
// example data
x = linspace(-4,4,100);
y = 16 - x.^2;
plot(x,y); hold on
ax1 = gca;
set(ax1,'box','off') %// here you can basically decide whether you like ticks on
%// top and on the right side or not
%// new white bounding box on top
ax2 = axes('Position', get(ax1, 'Position'),'Color','none');
set(ax2,'XTick',[],'YTick',[],'XColor','w','YColor','w','box','on','layer','top')
%// you can plot more afterwards and it doesn't effect the white box.
plot(ax1,x,-y); hold on
ylim(ax1,[-30,30])
Important is to deactivate the ticks of the second axes, to keep the ticks of the f rist one.
In Luis Mendo's solution, the plotted lines are fixed and stay at their initial position if you change the axes properties afterwards. That won't happen here, they get adjusted to the new limits. Use the correct handle for every command and there won't be much problems.
Dan's solution is easier, but does not apply for Matlab versions before R2014b.
There is another undocumented way (applicable to MATLAB R2014b and later versions) of removing the lines by changing the 'LineStyle' of rulers to 'none'.
Example:
figure;
plot(1:4,'o-'); %Plotting some data
pause(0.1); %Just to make sure that the plot is made before the next step
hAxes = gca; %Axis handle
%Changing 'LineStyle' to 'none'
hAxes.XRuler.Axle.LineStyle = 'none';
hAxes.YRuler.Axle.LineStyle = 'none';
%Default 'LineStyle': 'solid', Other possibilities: 'dashed', 'dotted', 'dashdot'
This is different from Dan's answer which uses the 'visible' property of rulers.
You could "erase" the axis lines by plotting a white line over them:
plot(1:4,1:4) %// example plot
box off %// remove outer border
hold on
a = axis; %// get axis size
plot([a(1) a(2)],[a(3) a(3)],'w'); %// plot white line over x axis
plot([a(1) a(1)],[a(3) a(4)],'w'); %// plot white line over y axis
Result:
As noted by #SardarUsama, in recent Matlab versions you may need to adjust the line width to cover the axes:
plot(1:4,1:4) %// example plot
box off %// remove outer border
hold on
a = axis; %// get axis size
plot([a(1) a(2)],[a(3) a(3)],'w', 'linewidth', 1.5); %// plot white line over x axis.
%// Set width manually
plot([a(1) a(1)],[a(3) a(4)],'w', 'linewidth', 1.5);
I'm trying to position MATLAB's ticks to line up with my grid, but I can't find a good way to offset the labels.
Also, if I run set(gca,'XTickLabel',1:10), my x tick labels end up ranging from 1 to 5. What gives?
You need to move the ticks, but get the labels before and write them back after moving:
f = figure(1)
X = randi(10,10,10);
surf(X)
view(0,90)
ax = gca;
XTick = get(ax, 'XTick')
XTickLabel = get(ax, 'XTickLabel')
set(ax,'XTick',XTick+0.5)
set(ax,'XTickLabel',XTickLabel)
YTick = get(ax, 'YTick')
YTickLabel = get(ax, 'YTickLabel')
set(ax,'YTick',YTick+0.5)
set(ax,'YTickLabel',YTickLabel)
Or if you know everything before, do it manually from the beginning:
[N,M] = size(X)
set(ax,'XTick',0.5+1:N)
set(ax,'XTickLabel',1:N)
set(ax,'YTick',0.5+1:M)
set(ax,'YTickLabel',1:M)
The marked answer works with a surf or mesh plot, however, I needed a solution which worked for a 2d plot.
This can be done by creating two axes, one to display the grid and the other to display the labels as follows
xlabels=1:1:10; %define where we want to see the labels
xgrid=0.5:1:10.5; %define where we want to see the grid
plot(xlabels,xlabels.^2); %plot a parabola as an example
set(gca,'xlim',[min(xgrid) max(xgrid)]); %set axis limits so we can see all the grid lines
set(gca,'XTickLabel',xlabels); %print the labels on this axis
axis2=copyobj(gca,gcf); %make an identical copy of the current axis and add it to the current figure
set(axis2,'Color','none'); %make the new axis transparent so we can see the plot
set(axis2,'xtick',xgrid,'XTickLabel',''); %set the tick marks to the grid, turning off labels
grid(axis2,'on'); %turn on the grid
This script displays the following figure :
I need to plot several plots along a sloped line at different positions.
For example, if I:
plot(0:200,'k');
plotpts = 5:5:200;
I would like to be able to plot a smaller plot at each of my plotpts on top of the original 0:200 line.
I know you can use hold on and plot over top that way, but I need to change my origin each time. Does anyone have any suggestions? I would really like to stay in matlab. Thanks!
Here is a flexible way I usually do it:
plot(1:10, 'k')
plotpts = 2:2:8;
mainbox = get(gca, 'Position');
xlims = get(gca, 'XLim');
ylims = get(gca, 'Ylim');
for i=1:length(plotpts)
originx = mainbox(1) + (plotpts(i) - xlims(1)) * (mainbox(3)) / (xlims(2) - xlims(1));
originy = mainbox(2) + (plotpts(i) - ylims(1)) * (mainbox(4)) / (ylims(2) - ylims(1));
axes('position', [originx originy 0.1 0.1], 'Color', 'none')
% Do some plotting here...
end
It's quite a bit of work, but you probably want to use the axes command. A figure window can host any number of axes, where each axes has it's own position, data, annotations, color etc.
The most difficult thing for the application you describe is that each axis position needs to be defined in the coordinate frame of the underlying figure, which means that some math may be required to create the illusion that the axis is correctly positioned within a parent axes/
For example, if you first create a simple plot
figure(1234); clf;
plot(1:10, rand(1,10),'.k-','linewidth',5);
xlim([1 10]);
ylim([0 1]);
set(gca,'color','y'); %This just helps demonstrate the next steps
You can place another axis directly on top of the first, and then
ha = axes('position',[.2 .3 .1 .1])
plot(linspace(0,2*pi,100), sin(linspace(0,2*pi,100)), 'b-')
xlim([0 2*pi])
You can adjust the the properties of the inset axis to suit your particular needs, for example
set(ha,'color','none'); %A transparent axis
set(ha,'xtick',[],'ytick',[]); %Remove tick labels
title(ha,'This is an inset plot')
Is the command subplot not what you're looking for?