this is the first time that I post something on stackoverflow, so please excuse me if the post is not top quality.
I am trying to make a figure in MATLAB with some interconnected nodes arranged in a circle, and I would like to label each of these nodes (for example, 1 2 3, etc.). When I use this sample code with the "Rotation" commented out (last line), I get badly aligned text labels. What can I do to have them equidistantly placed from the node plot without having to rotate the text? Thank you all in advance! (I attach the figure that the code is generating).
%# 60-by-60 sparse adjacency matrix
A = bucky();
N = length(A);![enter image description here][1]
%# x/y coordinates of nodes in a circular layout
r = 1;
theta = linspace(0,2*pi,N+1)'; theta(end) = [];
xy = r .* [cos(theta) sin(theta)];
%# labels of nodes
txt = cellstr(num2str((1:N)','%02d'));
%# show nodes and edges
figure(123)
line(xy(:,1), xy(:,2), 'LineStyle','none', ...
'Marker','.', 'MarkerSize',15, 'Color','g')
hold on
gplot(A, xy, 'b-')
axis([-1 1 -1 1]); axis equal off
hold off
%# show node labels
h = text(xy(:,1).*1.05, xy(:,2).*1.05, txt, 'FontSize',8);
%set(h, {'Rotation'},num2cell(theta*180/pi))
I think the issue is your text is aligned left. You put your text boxes at all the points around the circle plus some radial offset. This causes your text labels to appear off center with the left alignment. If you change the text alignment to center this will alleviate this issue.
The following is an example edit to your code you can use to achieve what you want. Note, I also increased the radial offset a little too.
%# show node labels
h = text(xy(:,1).*1.08, xy(:,2).*1.08, txt, 'FontSize',8);
set(h, {'HorizontalAlignment'},{'center'})
Related
I have a bar graph with 2 different data (each with a different color as you can see on the picture). I would like to move the x-axis so it crosses at y=-100 (for example). So if a data = -40, I would like to have a bar from -100 to -40.
An other question : is it possible to write each value of the x-axis vertically (because with all the values, we can't see anything).
The last question : is it possible to have 2 different scales for the x_axis ?
Thank you in advance,
Best regards,
Here is some code to get you going. Everything is commented so that should be easy to follow:
clear
clc
close all
%// Generate dummy data
y = -90*rand(1,20);
NumY = numel(y);
HalfData = round(NumY/2);
%// Loop to color half in pink and half in blue
hold all
for k = 1:NumY
hBar = bar(k,y(k));
if k <= HalfData
set(hBar,'FaceColor',[1 0 1])
else
set(hBar,'FaceColor',[0 0 1])
end
end
hold off
%// Get xtick labels and position for future use
xtLabels = cellstr(get(gca,'XTickLabel')).';
xtPos = get(gca,'XTick');
%// Change baseline value
set(hBar,'BaseValue',-40)
%// Get baseline to change its properties if you want
hBaseL = get(hBar,'Baseline');
set(hBaseL,'LineStyle','--','Color','k','LineWidth',3)
%// Adjust axis limits. Remove labels to place them vertically
set(gca,'XLim',[0 NumY],'XTickLabel',{''})
%// Get correct position for xlabel text
YLimPoArrays = min(get(gca,'YLim'));
YLimPoArrays = repmat(YLimPoArrays,numel(xtPos),1);
%// Place text positioned vertically with a small y offset
text(xtPos,YLimPoArrays-3,xtLabels,'HorizontalAlignment','center','Rotation',90,'FontSize',15)
And the output:
Hope that helps!
I am trying to create area plots with 2 y-axis using plotyy by using 'area' function. I don't want to have any tick marks or labels or titles but I just want the outside box. I would also like to save just the plot (not the entire figure window) as a png file.
When I turn off the x and y-axis ticks and labels, the box looks thin on the bottom and left, thick on the top and right. What am I doing wrong?
Also, if I try to make the box 'LineWidth' fat, I see two tick marks at the bottom left and bottom right - which ruin the plot and I am unable to remove. Can someone help?
My test code is below:
x = 1:100;
y1 = rand(size(x));
y2 = 100*rand(size(x));
fig_handle = figure('units','inches','position',[1 1 9 3]);
[a,p1,p2] = plotyy(x,y1,x,y2,'area');
c1 = get(p1,'child');
c2 = get(p2,'child');
set(c1,'facea',0.5,'FaceColor','b','EdgeColor',[0 0 0]);
set(c2,'facea',0.5,'FaceColor','r','EdgeColor',[0 0 0]);
set(c1,'Line','None');
set(c2,'Line','None');
set(a,'Layer','top')
set(a,'XTick',[]);
set(a(1),'YTick',[]);
set(a(2),'YTick',[]);
set(a,'TickDir','in')
set(a,'LineWidth',5);
Also, notice how the left Y-axis has red area on it, while the right Y-axis doesn't. Is this fix-able?
Any help would be appreciated! Also, I am new to StackOverflow - so, if these are too many questions in one post, please pardon me and I will post them as separate requests/questions.
Here is a workaround for the red appearing on the left Y-axis.
Since the axes line is quite thick, the data displayed close to it is drawn over it. To avoid this, you can slightly shift the x limits of the axes to make more room for the data. Do so by changing the XLim property of either axes since they share the same x limit:
XL = get(a,'Xlim');
xl = XL{1}; %// here XL{1} and XL{2} are the same...[1 100]
set(a(:),'Xlim',[xl(1)-.5 xl(2)+.5])
As for the annoying tick marks at the bottom of the plot, I must say that I don't know how to remove them while keeping the axes visible.
As an alternative solution to plotyy, here is a way to obtain a good result (I think) without plotyy. The trick is to superimpose 2 axes and make both of them not visible, then set the figure's color to white and add a black rectangle surrounding the plot.
Here is the code:
clear
clc
close all
x = 1:100;
y1 = rand(size(x));
y2 = 100*rand(size(x));
H1 = area(x,y1);
%// Set the figure color to white
set(gcf,'Color','w')
%// Plot data and set different properties for each axes
A1 = gca;
A2 = axes('Position',get(A1,'Position'));
H2 = area(x,y2);
set(A2,'YAxisLocation','right','Color','none','XTickLabel',[]);
set(A2,'XLim',get(A1,'XLim'),'XTick',[],'YTick',[]);
set(A1,'XTick',[],'YTick',[]);
%// Make both axes not visible.
set(A2,'Visible','off')
set(A1,'Visible','off')
axes(A1)
%// Get axes limits
XL = get(gca,'XLim');
YL= get(gca,'YLim');
%// Create rectangle as a bounding box
rectangle('Position',[XL(1) YL(1) XL(2)-1 YL(2)],'LineWidth',5)
%//===
%// Change the data color/properties
hP = findobj('Type','patch');
set(hP(1),'FaceColor','b','FaceAlpha',.5,'EdgeColor',[0 0 0],'line','none')
set(hP(2),'FaceColor','r','FaceAlpha',.5,'EdgeColor',[0 0 0],'line','none')
And the output:
It's not perfect but hope that helps!
I have a curve in which the minimum point is not obvious to the naked eye. For that reason I'm looking to highlight the minimum point using a marker.
Ideally I would highlight the point with a marker and also have its coordinates displayed in text on the figure.
You can do it this way:
%// Example plot
x = 1:10;
y = randn(1,10);
plot(x,y)
%// Marker at minimum
[ymin imin] = min(y);
xmin = x(imin);
hold on
style = 'ro'; %// red circle. Change as needed
markersize = 10; %// change as needed
plot(x(imin), ymin, style, 'markersize', markersize)
%// Text with coordinates of minimum
offset = -.05; %// vertical offset as a fraction of y-axis span. Change as needed.
text(x(imin),ymin+diff(ylim)*offset,['(' num2str(x(imin)) ',' num2str(ymin) ')'])
%// Enlarge y axis so that text is properly seen, if offset is negative
ylim(ylim+[diff(ylim)*offset*(offset<0) 0])
You might also want to enlarge the x axis if the text is close to the left or to the right. It could be done with xlim in a similar way.
Assuming you know the coordinates of that point, you can do something like:
hold on; % add things to the current figure
plot(x_coord, y_coord, '+r')
This will put a red plus sign at that point.
This should plot the minimum point(s), assuming you have data like y and x,
plot(x(y==min(y)),min(y),'o')
adding the text could be trickier depending on what you want, but at least these are the coordinates.
I need to know how to align an image in Matlab for further work.
for example I have the next license plate image and I want to recognize all
the digits.
my program works for straight images so, I need to align the image and then
preform the optical recognition system.
The method should be as much as universal that fits for all kinds of plates and in all kinds of angles.
EDIT: I tried to do this with Hough Transform but I didn't Succeed. anybody can help me do to this?
any help will be greatly appreciated.
The solution was first hinted at by #AruniRC in the comments, then implemented by #belisarius in Mathematica. The following is my interpretation in MATLAB.
The idea is basically the same: detect edges using Canny method, find prominent lines using Hough Transform, compute line angles, finally perform a Shearing Transform to align the image.
%# read and crop image
I = imread('http://i.stack.imgur.com/CJHaA.png');
I = I(:,1:end-3,:); %# remove small white band on the side
%# egde detection
BW = edge(rgb2gray(I), 'canny');
%# hough transform
[H T R] = hough(BW);
P = houghpeaks(H, 4, 'threshold',ceil(0.75*max(H(:))));
lines = houghlines(BW, T, R, P);
%# shearing transforma
slopes = vertcat(lines.point2) - vertcat(lines.point1);
slopes = slopes(:,2) ./ slopes(:,1);
TFORM = maketform('affine', [1 -slopes(1) 0 ; 0 1 0 ; 0 0 1]);
II = imtransform(I, TFORM);
Now lets see the results
%# show edges
figure, imshow(BW)
%# show accumlation matrix and peaks
figure, imshow(imadjust(mat2gray(H)), [], 'XData',T, 'YData',R, 'InitialMagnification','fit')
xlabel('\theta (degrees)'), ylabel('\rho'), colormap(hot), colorbar
hold on, plot(T(P(:,2)), R(P(:,1)), 'gs', 'LineWidth',2), hold off
axis on, axis normal
%# show image with lines overlayed, and the aligned/rotated image
figure
subplot(121), imshow(I), hold on
for k = 1:length(lines)
xy = [lines(k).point1; lines(k).point2];
plot(xy(:,1), xy(:,2), 'g.-', 'LineWidth',2);
end, hold off
subplot(122), imshow(II)
In Mathematica, using Edge Detection and Hough Transform:
If you are using some kind of machine learning toolbox for text recognition, try to learn from ALL plates - not only aligned ones. Recognition results should be equally well if you transform the plate or dont, since by transforming, no new informations according to the true number will enhance the image.
If all the images have a dark background like that one, you could binarize the image, fit lines to the top or bottom of the bright area and calculate an affine projection matrix from the line gradient.
Let's say I have 9 MxN black and white images that are in some way related to one another (i.e. time lapse of some event). What is a way that I can display all of these images on one surface plot?
Assume the MxN matrices only contain 0's and 1's. Assume the images simply contain white lines on a black background (i.e. pixel value == 1 if that pixel is part of a line, 0 otherwise). Assume images are ordered in such a way as to suggest movement progression of line(s) in subsequent images. I want to be able to see a "side-view" (or volumetric representation) of these images which will show the surface that a particular line "carves out" in its movement across the images.
Coding is done in MATLAB. I have looked at plot (but it only does 2D plots) and surf, which does 3D plots but doesn't work for my MxNx9 matrix of images. I have also tried to experiment with contourslice, but not sure what parameters to pass it.
Thanks!
Mariya
Are these images black and white with simple features on a "blank" field, or greyscale, with more dense information?
I can see a couple of approaches.
You can use movie() to display a sequence of images as an animation.
For a static view of sparse, simple data, you could plot each image as a separate layer in a single figure, giving each layer a different color for the foreground, and using AlphaData to make the background transparent so all the steps in the sequenc show through. The gradient of colors corresponds to position in the image sequence. Here's an example.
function plotImageSequence
% Made-up test data
nLayers = 9;
x = zeros(100,100,nLayers);
for i = 1:nLayers
x(20+(3*i),:,i) = 1;
end
% Plot each image as a "layer", indicated by color
figure;
hold on;
for i = 1:nLayers
layerData = x(:,:,i);
alphaMask = layerData == 1;
layerData(logical(layerData)) = i; % So each layer gets its own color
image('CData',layerData,...
'AlphaData',alphaMask,...
'CDataMapping','scaled');
end
hold off
Directly showing the path of movement a "line" carves out is hard with raster data, because Matlab won't know which "moved" pixels in two subsequent images are associated with each other. Don't suppose you have underlying vector data for the geometric features in the images? Plot3() might allow you to show their movement, with time as the z axis. Or you could use the regular plot() and some manual fiddling to plot the paths of all the control points or vertexes in the geometric features.
EDIT: Here's a variation that uses patch() to draw each pixel as a little polygon floating in space at the Z level of its index in the image sequence. I think this will look more like the "surface" style plots you are asking for. You could fiddle with the FaceAlpha property to make dense plots more legible.
function plotImageSequencePatch
% Made-up test data
nLayers = 6;
sz = [50 50];
img = zeros(sz(1),sz(2),nLayers);
for i = 1:nLayers
img(20+(3*i),:,i) = 1;
end
% Plot each image as a "layer", indicated by color
% With each "pixel" as a separate patch
figure;
set(gca, 'XLim', [0 sz(1)]);
set(gca, 'YLim', [0 sz(2)]);
hold on;
for i = 1:nLayers
layerData = img(:,:,i);
[x,y] = find(layerData); % X,Y of all pixels
% Reshape in to patch outline
x = x';
y = y';
patch_x = [x; x+1; x+1; x];
patch_y = [y; y; y+1; y+1];
patch_z = repmat(i, size(patch_x));
patch(patch_x, patch_y, patch_z, i);
end
hold off