.. only:: html .. 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_pyplots_axline.py: ============== Infinite lines ============== ~.axes.Axes.axvline and ~.axes.Axes.axhline draw infinite vertical / horizontal lines, at given *x* / *y* positions. They are usually used to mark special data values, e.g. in this example the center and limit values of the sigmoid function. ~.axes.Axes.axline draws infinite straight lines in arbitrary directions. .. code-block:: default import numpy as np import matplotlib.pyplot as plt t = np.linspace(-10, 10, 100) sig = 1 / (1 + np.exp(-t)) plt.axhline(y=0, color="black", linestyle="--") plt.axhline(y=0.5, color="black", linestyle=":") plt.axhline(y=1.0, color="black", linestyle="--") plt.axvline(color="grey") plt.axline((0, 0.5), slope=0.25, color="black", linestyle=(0, (5, 5))) plt.plot(t, sig, linewidth=2, label=r"$\sigma(t) = \frac{1}{1 + e^{-t}}$") plt.xlim(-10, 10) plt.xlabel("t") plt.legend(fontsize=14) plt.show() .. image:: /gallery/pyplots/images/sphx_glr_axline_001.png :alt: axline :class: sphx-glr-single-img ~.axes.Axes.axline can also be used with a transform parameter, which applies to the point, but not to the slope. This can be useful for drawing diagonal grid lines with a fixed slope, which stay in place when the plot limits are moved. .. code-block:: default for pos in np.linspace(-2, 1, 10): plt.axline((pos, 0), slope=0.5, color='k', transform=plt.gca().transAxes) plt.ylim([0, 1]) plt.xlim([0, 1]) plt.show() .. image:: /gallery/pyplots/images/sphx_glr_axline_002.png :alt: axline :class: sphx-glr-single-img ------------ References """""""""" The use of the following functions, methods, classes and modules is shown in this example: .. code-block:: default import matplotlib matplotlib.pyplot.axhline matplotlib.pyplot.axvline matplotlib.pyplot.axline matplotlib.axes.Axes.axhline matplotlib.axes.Axes.axvline matplotlib.axes.Axes.axline .. rst-class:: sphx-glr-script-out Out: .. code-block:: none .. _sphx_glr_download_gallery_pyplots_axline.py: .. only :: html .. container:: sphx-glr-footer :class: sphx-glr-footer-example .. container:: sphx-glr-download sphx-glr-download-python :download:Download Python source code: axline.py  .. container:: sphx-glr-download sphx-glr-download-jupyter :download:Download Jupyter notebook: axline.ipynb  .. only:: html .. rst-class:: sphx-glr-signature Keywords: matplotlib code example, codex, python plot, pyplot Gallery generated by Sphinx-Gallery _