.. note:: :class: sphx-glr-download-link-note Click :ref:`here ` to download the full example code .. rst-class:: sphx-glr-example-title .. _sphx_glr_gallery_images_contours_and_fields_plot_streamplot.py: ========== Streamplot ========== A stream plot, or streamline plot, is used to display 2D vector fields. This example shows a few features of the :meth:`~.axes.Axes.streamplot` function: * Varying the color along a streamline. * Varying the density of streamlines. * Varying the line width along a streamline. * Controlling the starting points of streamlines. * Streamlines skipping masked regions and NaN values. .. code-block:: default import numpy as np import matplotlib.pyplot as plt import matplotlib.gridspec as gridspec w = 3 Y, X = np.mgrid[-w:w:100j, -w:w:100j] U = -1 - X**2 + Y V = 1 + X - Y**2 speed = np.sqrt(U**2 + V**2) fig = plt.figure(figsize=(7, 9)) gs = gridspec.GridSpec(nrows=3, ncols=2, height_ratios=[1, 1, 2]) # Varying density along a streamline ax0 = fig.add_subplot(gs[0, 0]) ax0.streamplot(X, Y, U, V, density=[0.5, 1]) ax0.set_title('Varying Density') # Varying color along a streamline ax1 = fig.add_subplot(gs[0, 1]) strm = ax1.streamplot(X, Y, U, V, color=U, linewidth=2, cmap='autumn') fig.colorbar(strm.lines) ax1.set_title('Varying Color') # Varying line width along a streamline ax2 = fig.add_subplot(gs[1, 0]) lw = 5*speed / speed.max() ax2.streamplot(X, Y, U, V, density=0.6, color='k', linewidth=lw) ax2.set_title('Varying Line Width') # Controlling the starting points of the streamlines seed_points = np.array([[-2, -1, 0, 1, 2, -1], [-2, -1, 0, 1, 2, 2]]) ax3 = fig.add_subplot(gs[1, 1]) strm = ax3.streamplot(X, Y, U, V, color=U, linewidth=2, cmap='autumn', start_points=seed_points.T) fig.colorbar(strm.lines) ax3.set_title('Controlling Starting Points') # Displaying the starting points with blue symbols. ax3.plot(seed_points[0], seed_points[1], 'bo') ax3.axis((-w, w, -w, w)) # Create a mask mask = np.zeros(U.shape, dtype=bool) mask[40:60, 40:60] = True U[:20, :20] = np.nan U = np.ma.array(U, mask=mask) ax4 = fig.add_subplot(gs[2:, :]) ax4.streamplot(X, Y, U, V, color='r') ax4.set_title('Streamplot with Masking') ax4.imshow(~mask, extent=(-w, w, -w, w), alpha=0.5, interpolation='nearest', cmap='gray', aspect='auto') ax4.set_aspect('equal') plt.tight_layout() plt.show() .. image:: /gallery/images_contours_and_fields/images/sphx_glr_plot_streamplot_001.png :class: sphx-glr-single-img ------------ References """""""""" The use of the following functions and methods is shown in this example: .. code-block:: default import matplotlib matplotlib.axes.Axes.streamplot matplotlib.pyplot.streamplot matplotlib.gridspec matplotlib.gridspec.GridSpec .. rst-class:: sphx-glr-timing **Total running time of the script:** ( 0 minutes 1.267 seconds) .. _sphx_glr_download_gallery_images_contours_and_fields_plot_streamplot.py: .. only :: html .. container:: sphx-glr-footer :class: sphx-glr-footer-example .. container:: sphx-glr-download :download:`Download Python source code: plot_streamplot.py ` .. container:: sphx-glr-download :download:`Download Jupyter notebook: plot_streamplot.ipynb ` .. only:: html .. rst-class:: sphx-glr-signature Keywords: matplotlib code example, codex, python plot, pyplot `Gallery generated by Sphinx-Gallery `_