[Matplotlib-users] streamplot: vectors not pointing in the right direction!
Hi, I have problems with streamplot I want to use a 3d vector field in coordinates (x,y,z) stored in a numpy array, and plot slices of it with streamplot. To test it I wanted to use a vector field with arrows pointed up in the z0 region and pointed down in the z0 region. import numpy as np import matplotlib.pyplot as plt from math import * max = 100 min = -100 X = np.linspace(min, max, num=100) Y = np.linspace(min, max, num=100) Z = np.linspace(min, max, num=100) N = X.size #single components in the 3D matrix Bxa = np.zeros((N, N, N)) Bya = np.zeros((N, N, N)) Bza = np.zeros((N, N, N)) for i, x in enumerate(X): for j, y in enumerate(Y): for k, z in enumerate(Z): Bxa[ i, j, k] = 0.0 #x Bya[ i, j, k] = 0.0 #y Bza[ i, j, k] = z #I take a slice close to Y=0 Bx_sec = Bxa[:,N/2,:] By_sec = Bya[:,N/2,:] Bz_sec = Bza[:,N/2,:] fig = plt.figure() ax = fig.add_subplot(111) ax.streamplot(X, Z, Bx_sec, Bz_sec, color='b') ax.set_xlim([X.min(), X.max()]) ax.set_ylim([Z.min(), Z.max()]) plt.show() But I obtain something that looks like if I have put Bza = x! I tried to invert the order of vectors but it is unuseful! I attach the picture. Do you understand why? (the code I posted should run) Gabriele -- One dashboard for servers and applications across Physical-Virtual-Cloud Widest out-of-the-box monitoring support with 50+ applications Performance metrics, stats and reports that give you Actionable Insights Deep dive visibility with transaction tracing using APM Insight. http://ad.doubleclick.net/ddm/clk/290420510;117567292;y___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] streamplot: vectors not pointing in the right direction!
The documentation for streamplot: ``` *x*, *y* : 1d arrays an *evenly spaced* grid. *u*, *v* : 2d arrays x and y-velocities. Number of rows should match length of y, and the number of columns should match x. ``` Note that the rows in *u* and *v* should match *y*, and the columns should match *x*. I think your *u* and *v* are transposed. Cheers! Ben Root On Fri, May 22, 2015 at 2:50 AM, Gabriele Brambilla gb.gabrielebrambi...@gmail.com wrote: Hi, I have problems with streamplot I want to use a 3d vector field in coordinates (x,y,z) stored in a numpy array, and plot slices of it with streamplot. To test it I wanted to use a vector field with arrows pointed up in the z0 region and pointed down in the z0 region. import numpy as np import matplotlib.pyplot as plt from math import * max = 100 min = -100 X = np.linspace(min, max, num=100) Y = np.linspace(min, max, num=100) Z = np.linspace(min, max, num=100) N = X.size #single components in the 3D matrix Bxa = np.zeros((N, N, N)) Bya = np.zeros((N, N, N)) Bza = np.zeros((N, N, N)) for i, x in enumerate(X): for j, y in enumerate(Y): for k, z in enumerate(Z): Bxa[ i, j, k] = 0.0 #x Bya[ i, j, k] = 0.0 #y Bza[ i, j, k] = z #I take a slice close to Y=0 Bx_sec = Bxa[:,N/2,:] By_sec = Bya[:,N/2,:] Bz_sec = Bza[:,N/2,:] fig = plt.figure() ax = fig.add_subplot(111) ax.streamplot(X, Z, Bx_sec, Bz_sec, color='b') ax.set_xlim([X.min(), X.max()]) ax.set_ylim([Z.min(), Z.max()]) plt.show() But I obtain something that looks like if I have put Bza = x! I tried to invert the order of vectors but it is unuseful! I attach the picture. Do you understand why? (the code I posted should run) Gabriele -- One dashboard for servers and applications across Physical-Virtual-Cloud Widest out-of-the-box monitoring support with 50+ applications Performance metrics, stats and reports that give you Actionable Insights Deep dive visibility with transaction tracing using APM Insight. http://ad.doubleclick.net/ddm/clk/290420510;117567292;y ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users -- One dashboard for servers and applications across Physical-Virtual-Cloud Widest out-of-the-box monitoring support with 50+ applications Performance metrics, stats and reports that give you Actionable Insights Deep dive visibility with transaction tracing using APM Insight. http://ad.doubleclick.net/ddm/clk/290420510;117567292;y___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] streamplot: vectors not pointing in the right direction!
Thanks! you are right! I didn't notice this detail Gabriele On Fri, May 22, 2015 at 3:58 PM, Benjamin Root ben.r...@ou.edu wrote: The documentation for streamplot: ``` *x*, *y* : 1d arrays an *evenly spaced* grid. *u*, *v* : 2d arrays x and y-velocities. Number of rows should match length of y, and the number of columns should match x. ``` Note that the rows in *u* and *v* should match *y*, and the columns should match *x*. I think your *u* and *v* are transposed. Cheers! Ben Root On Fri, May 22, 2015 at 2:50 AM, Gabriele Brambilla gb.gabrielebrambi...@gmail.com wrote: Hi, I have problems with streamplot I want to use a 3d vector field in coordinates (x,y,z) stored in a numpy array, and plot slices of it with streamplot. To test it I wanted to use a vector field with arrows pointed up in the z0 region and pointed down in the z0 region. import numpy as np import matplotlib.pyplot as plt from math import * max = 100 min = -100 X = np.linspace(min, max, num=100) Y = np.linspace(min, max, num=100) Z = np.linspace(min, max, num=100) N = X.size #single components in the 3D matrix Bxa = np.zeros((N, N, N)) Bya = np.zeros((N, N, N)) Bza = np.zeros((N, N, N)) for i, x in enumerate(X): for j, y in enumerate(Y): for k, z in enumerate(Z): Bxa[ i, j, k] = 0.0 #x Bya[ i, j, k] = 0.0 #y Bza[ i, j, k] = z #I take a slice close to Y=0 Bx_sec = Bxa[:,N/2,:] By_sec = Bya[:,N/2,:] Bz_sec = Bza[:,N/2,:] fig = plt.figure() ax = fig.add_subplot(111) ax.streamplot(X, Z, Bx_sec, Bz_sec, color='b') ax.set_xlim([X.min(), X.max()]) ax.set_ylim([Z.min(), Z.max()]) plt.show() But I obtain something that looks like if I have put Bza = x! I tried to invert the order of vectors but it is unuseful! I attach the picture. Do you understand why? (the code I posted should run) Gabriele -- One dashboard for servers and applications across Physical-Virtual-Cloud Widest out-of-the-box monitoring support with 50+ applications Performance metrics, stats and reports that give you Actionable Insights Deep dive visibility with transaction tracing using APM Insight. http://ad.doubleclick.net/ddm/clk/290420510;117567292;y ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users -- One dashboard for servers and applications across Physical-Virtual-Cloud Widest out-of-the-box monitoring support with 50+ applications Performance metrics, stats and reports that give you Actionable Insights Deep dive visibility with transaction tracing using APM Insight. http://ad.doubleclick.net/ddm/clk/290420510;117567292;y___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
