[Matplotlib-users] find the projected distance between two curves
Hello list, I'm completely new to matplotlib and I'm not a computer scientist (not a good starting point!) but I need to solve a geometric/graphical problem. I've been asked to find a method, in Python, to find the distance between a 2D polynomial curve, derived from least squares interpolation on a set of points, and a curve locallly interpolating another set of points. - the starting line is a smooth line, while the second should describe a path passing exactly thorugh the given points. - the distance should be the one along the normal to the first line I attach a sketch to explain this. Is there an heuristic, an algorithm, to solve this problem in an efficient way (I have to apply it to thousands couples of sets from sonar and seismic acquisitions)? Is the mapltolip API useful for this? Thanks in advance, Giovanni attachment: linesnormalsketch.png-- Open Source Business Conference (OSBC), March 24-25, 2009, San Francisco, CA -OSBC tackles the biggest issue in open source: Open Sourcing the Enterprise -Strategies to boost innovation and cut costs with open source participation -Receive a $600 discount off the registration fee with the source code: SFAD http://p.sf.net/sfu/XcvMzF8H___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
[Matplotlib-users] Polar bars and matplotlib 0.98.5
hi, I'm using polar bars to plot windroses. Since the 0.98.5 version i have some issues with the plots. The 0° bar is not displayed in the good way. This bar is located between -0.26 radian and 0.26 radian but it is printed counterclockwise. It was working perfectly with matplotlib version 0.98.3. I just switched to version 0.98.5 because of the NaN bug of the previous version. Any idea how i could make it work again ? Ty!! from pylab import * nb_secteur=12 fig = figure(2,figsize=(8,8)) ax = fig.add_axes([0.1, 0.1, 0.8, 0.8], polar=True,) thetagrids([90,45,0,315,270,225,180,135], labels=[N,NE,E,SE,S,SO,O,NO]) theta = arange(0.0-pi/nb_secteur, 2*pi-pi/nb_secteur, 2*pi/nb_secteur) radii = [10.,20,10,5,3,4,3,4,6,4,2,9] width = 2*pi/nb_secteur bars = ax.bar(theta, radii, width=width, bottom=0.0 ) for r,bar in zip(radii, bars): bar.set_facecolor( 'blue') bar.set_alpha(0.3) text(1,0.69,%,transform = ax.transAxes) show() -- Open Source Business Conference (OSBC), March 24-25, 2009, San Francisco, CA -OSBC tackles the biggest issue in open source: Open Sourcing the Enterprise -Strategies to boost innovation and cut costs with open source participation -Receive a $600 discount off the registration fee with the source code: SFAD http://p.sf.net/sfu/XcvMzF8H___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] Venn diagrams
Ian Harry wrote: Hi all, Is there any simple way in matplotlib, or in any other python library, to make a simple Venn diagram, I want to show three events and their intersections? I have tried googling for any hints but didn't find anything. You can use Sage (http://www.sagemath.org or http://sagenb.org) http://wiki.sagemath.org/interact/misc#AnInteractiveVennDiagram (scroll down to see the picture; email me off-list if you'd like help in setting up an account or installing Sage; you can use Sage as a python library). Even if you don't use Sage and something like the interactive Venn diagram listed in the URL gives you relevant code for creating such a thing in matplotlib. Sage uses matplotlib in the background to actually draw the Venn diagram. Thanks, Jason -- Open Source Business Conference (OSBC), March 24-25, 2009, San Francisco, CA -OSBC tackles the biggest issue in open source: Open Sourcing the Enterprise -Strategies to boost innovation and cut costs with open source participation -Receive a $600 discount off the registration fee with the source code: SFAD http://p.sf.net/sfu/XcvMzF8H ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
[Matplotlib-users] errors when plotting random vectors
hi all, i'm trying to do something extremely simple, namely print a scatter plot of two random arrays: import matplotlib.plt as plt from numpy.random import * x = rand(1,10) scatter(x, x) this fails with the error: ValueError: Offsets array must be Nx2 what is happening here? are arrays somehow weird? do they not behave like lists? any info on this will be greatly appreciated. thank you. -- Open Source Business Conference (OSBC), March 24-25, 2009, San Francisco, CA -OSBC tackles the biggest issue in open source: Open Sourcing the Enterprise -Strategies to boost innovation and cut costs with open source participation -Receive a $600 discount off the registration fee with the source code: SFAD http://p.sf.net/sfu/XcvMzF8H___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
[Matplotlib-users] making points cross in simple plots
hi all, when plotting a simple scatter plot in matlab, points that overlap will cross in each other -- if i plot scatter(randn(1,1000),randn(1,1000)) then no point will be fully on top of the other -- if they overlap, then their edges will cross and they will look like tiny venn diagrams. in matplotlib, this is not the case, and points that overlap are placed on top of each other. for example if i use: x = randn(1,1000) plot(x, x, 'bo') how can i fix it so that it looks like matlab and points cross? more importantly, the above command in matplotlib generates many many line objects and takes forever to render. if i don't specify 'bo' and simply call plot(x, x, 'o') it makes every point in a *different color*. why is that? how can i change that? i feel like i must be doing something wrong here. thanks. -- Open Source Business Conference (OSBC), March 24-25, 2009, San Francisco, CA -OSBC tackles the biggest issue in open source: Open Sourcing the Enterprise -Strategies to boost innovation and cut costs with open source participation -Receive a $600 discount off the registration fee with the source code: SFAD http://p.sf.net/sfu/XcvMzF8H___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] errors when plotting random vectors
per freem wrote: hi all, i'm trying to do something extremely simple, namely print a scatter plot of two random arrays: import matplotlib.plt as plt from numpy.random import * x = rand(1,10) scatter(x, x) this fails with the error: ValueError: Offsets array must be Nx2 what is happening here? are arrays somehow weird? do they not behave like lists? any info on this will be greatly appreciated. Your x is 2-D; what you want is rand(10); or you can do scatter(x.ravel(), x.ravel()). Your example does point to a bug in scatter, however; it should not be failing with an obscure error message like that. (In mpl from svn trunk it still fails, but with a different obscure error message.) I don't know any good reason why it should not be able to handle the 2-D inputs. I will take a look. Eric thank you. -- Open Source Business Conference (OSBC), March 24-25, 2009, San Francisco, CA -OSBC tackles the biggest issue in open source: Open Sourcing the Enterprise -Strategies to boost innovation and cut costs with open source participation -Receive a $600 discount off the registration fee with the source code: SFAD http://p.sf.net/sfu/XcvMzF8H ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users -- Open Source Business Conference (OSBC), March 24-25, 2009, San Francisco, CA -OSBC tackles the biggest issue in open source: Open Sourcing the Enterprise -Strategies to boost innovation and cut costs with open source participation -Receive a $600 discount off the registration fee with the source code: SFAD http://p.sf.net/sfu/XcvMzF8H ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] making points cross in simple plots
per freem wrote: hi all, when plotting a simple scatter plot in matlab, points that overlap will cross in each other -- if i plot scatter(randn(1,1000),randn(1,1000)) then no point will be fully on top of the other -- if they overlap, then their edges will cross and they will look like tiny venn diagrams. in matplotlib, this is not the case, and points that overlap are placed on top of each other. for example if i use: x = randn(1,1000) plot(x, x, 'bo') how can i fix it so that it looks like matlab and points cross? So you want the interiors of the points to be transparent? Add the keyword argument mfc='none'. I may be misunderstanding the desired effect, however. more importantly, the above command in matplotlib generates many many line objects and takes forever to render. if i don't specify 'bo' and Again, you are using 2-D arrays when you should be using 1-D. In matlab, everything is a 2-D matrix (or it used to be, until higher dimensions were clumsily patched in). Numpy is designed to use as many or as few dimensions as you need. Mpl plot(x, y) with x and y being MxN is assuming each of the N columns is a line, so it is plotting N lines--as well as cycling through the colors, one per line, if you don't explicitly give a color. simply call plot(x, x, 'o') it makes every point in a *different color*. why is that? how can i change that? i feel like i must be doing something wrong here. It's just a Matlab hangover--a common malady, painful but rarely fatal. Eric -- Open Source Business Conference (OSBC), March 24-25, 2009, San Francisco, CA -OSBC tackles the biggest issue in open source: Open Sourcing the Enterprise -Strategies to boost innovation and cut costs with open source participation -Receive a $600 discount off the registration fee with the source code: SFAD http://p.sf.net/sfu/XcvMzF8H ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] find the projected distance between two curves
G. Allegri wrote: Hello list, I'm completely new to matplotlib and I'm not a computer scientist (not a good starting point!) but I need to solve a geometric/graphical problem. I've been asked to find a method, in Python, to find the distance between a 2D polynomial curve, derived from least squares interpolation on a set of points, and a curve locallly interpolating another set of points. Do you really need the distance to be relative to the interpolated curve? Why not to the points which are being interpolated? Then the answer is just: Sum_i dist(point_i,polynomial_curve) Where dist() can be arrived at in closed form... Otherwise, I guess it would depend on the interpolation, which you didn't really specify. - the starting line is a smooth line, while the second should describe a path passing exactly thorugh the given points. - the distance should be the one along the normal to the first line I attach a sketch to explain this. Is there an heuristic, an algorithm, to solve this problem in an efficient way (I have to apply it to thousands couples of sets from sonar and seismic acquisitions)? Is the mapltolip API useful for this? Thanks in advance, Giovanni -- Open Source Business Conference (OSBC), March 24-25, 2009, San Francisco, CA -OSBC tackles the biggest issue in open source: Open Sourcing the Enterprise -Strategies to boost innovation and cut costs with open source participation -Receive a $600 discount off the registration fee with the source code: SFAD http://p.sf.net/sfu/XcvMzF8H ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users -- Open Source Business Conference (OSBC), March 24-25, 2009, San Francisco, CA -OSBC tackles the biggest issue in open source: Open Sourcing the Enterprise -Strategies to boost innovation and cut costs with open source participation -Receive a $600 discount off the registration fee with the source code: SFAD http://p.sf.net/sfu/XcvMzF8H ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
