other:python:matplotlib_by_jyp
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other:python:matplotlib_by_jyp [2021/02/26 11:38] jypeter [Useful matplotlib reference pages] Updated gallery links |
other:python:matplotlib_by_jyp [2021/05/11 15:12] jypeter [Useful matplotlib reference pages] added tick formatters |
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| <wrap hi>A good way to start with matplotlib</wrap> is to quickly read this section, practice, and read this section again (and again) | <wrap hi>A good way to start with matplotlib</wrap> is to quickly read this section, practice, and read this section again (and again) | ||
| - | - Have a quick look at the [[https://matplotlib.org/gallery/index.html|matplotlib gallery]] to get an idea of all you can do with matplotlib. Later, when you need to plot something, go back to the gallery to find some examples that are close to what you need and click on them to view their source code | + | - Have a quick look at the [[https://matplotlib.org/stable/gallery/index.html|matplotlib gallery]] to get an idea of all you can do with matplotlib. Later, when you need to plot something, go back to the gallery to find some examples that are close to what you need and click on them to view their source code |
| * some examples are more //pythonic// (ie object oriented) than others, and some examples mix different styles of coding, which can be quite confusing. Try to [[http://matplotlib.org/faq/usage_faq.html#coding-styles|use an object oriented way of doing things]]! | * some examples are more //pythonic// (ie object oriented) than others, and some examples mix different styles of coding, which can be quite confusing. Try to [[http://matplotlib.org/faq/usage_faq.html#coding-styles|use an object oriented way of doing things]]! | ||
| - Use the free hints provided by JY! | - Use the free hints provided by JY! | ||
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| * ''my_plot.clear()'' or ''my_plot.cla()'': clear the (current) axis | * ''my_plot.clear()'' or ''my_plot.cla()'': clear the (current) axis | ||
| - some resources for having multiple plots on the same figure | - some resources for having multiple plots on the same figure | ||
| - | * [[https://matplotlib.org/gallery/recipes/create_subplots.html#sphx-glr-gallery-recipes-create-subplots-py|Easily creating subplots]] | + | * [[https://matplotlib.org/stable/gallery/recipes/create_subplots.html|Easily creating subplots]] |
| * [[https://matplotlib.org/api/_as_gen/matplotlib.figure.Figure.html#matplotlib.figure.Figure.add_subplot|fig.add_subplot(...)]] | * [[https://matplotlib.org/api/_as_gen/matplotlib.figure.Figure.html#matplotlib.figure.Figure.add_subplot|fig.add_subplot(...)]] | ||
| * [[https://matplotlib.org/api/_as_gen/matplotlib.figure.Figure.html#matplotlib.figure.Figure.add_axes|fig.add_axes(...)]] | * [[https://matplotlib.org/api/_as_gen/matplotlib.figure.Figure.html#matplotlib.figure.Figure.add_axes|fig.add_axes(...)]] | ||
| * [[https://matplotlib.org/api/_as_gen/matplotlib.pyplot.subplot.html|plt.subplot(...)]] | * [[https://matplotlib.org/api/_as_gen/matplotlib.pyplot.subplot.html|plt.subplot(...)]] | ||
| - | * [[https://matplotlib.org/api/_as_gen/matplotlib.pyplot.subplots.html|plt.subplots(...)]] with an **s** at the end ([[https://matplotlib.org/gallery/subplots_axes_and_figures/subplots_demo.html|demo]]) | + | * [[https://matplotlib.org/api/_as_gen/matplotlib.pyplot.subplots.html|plt.subplots(...)]] with an **s** at the end ([[https://matplotlib.org/stable/gallery/subplots_axes_and_figures/subplots_demo.html|demo]]) |
| * [[https://matplotlib.org/api/_as_gen/matplotlib.pyplot.subplots_adjust.html|subplots_adjust]] can be used to change the overall boundaries of the subplots on the figure, and the spacing between the subplots\\ ''plt.subplots_adjust(left=None, bottom=None, right=None, top=None, wspace=None, hspace=None)''\\ or ''my_page.subplots_adjust(left=None, bottom=None, right=None, top=None, wspace=None, hspace=None)'' | * [[https://matplotlib.org/api/_as_gen/matplotlib.pyplot.subplots_adjust.html|subplots_adjust]] can be used to change the overall boundaries of the subplots on the figure, and the spacing between the subplots\\ ''plt.subplots_adjust(left=None, bottom=None, right=None, top=None, wspace=None, hspace=None)''\\ or ''my_page.subplots_adjust(left=None, bottom=None, right=None, top=None, wspace=None, hspace=None)'' | ||
| * ''hspace''/''wspace'' is the amount of height/width between the subplots | * ''hspace''/''wspace'' is the amount of height/width between the subplots | ||
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| - Get the current size information: ''pl_x_bottomleft, pl_y_bottomleft, pl_width, pl_height = my_plot.get_position().bounds'' | - Get the current size information: ''pl_x_bottomleft, pl_y_bottomleft, pl_width, pl_height = my_plot.get_position().bounds'' | ||
| - Set the new size: e.g reduce the height with ''my_plot.set_position( (pl_x_bottomleft, pl_y_bottomleft, pl_width, pl_height * 0.5) )'' | - Set the new size: e.g reduce the height with ''my_plot.set_position( (pl_x_bottomleft, pl_y_bottomleft, pl_width, pl_height * 0.5) )'' | ||
| - | * [[https://matplotlib.org/gallery/index.html#subplots-axes-and-figures|Subplots, axes and figures]] gallery | + | * [[https://matplotlib.org/stable/gallery/index.html#subplots-axes-and-figures|Subplots, axes and figures]] gallery |
| * [[https://matplotlib.org/tutorials/intermediate/gridspec.html#sphx-glr-tutorials-intermediate-gridspec-py|Customizing Figure Layouts Using GridSpec and Other Functions]], [[https://matplotlib.org/tutorials/intermediate/constrainedlayout_guide.html|constrained layout]] and [[https://matplotlib.org/tutorials/intermediate/tight_layout_guide.html|tight layout]] | * [[https://matplotlib.org/tutorials/intermediate/gridspec.html#sphx-glr-tutorials-intermediate-gridspec-py|Customizing Figure Layouts Using GridSpec and Other Functions]], [[https://matplotlib.org/tutorials/intermediate/constrainedlayout_guide.html|constrained layout]] and [[https://matplotlib.org/tutorials/intermediate/tight_layout_guide.html|tight layout]] | ||
| - use [[https://matplotlib.org/api/_as_gen/matplotlib.pyplot.savefig.html|my_page.savefig(...)]] to save a figure | - use [[https://matplotlib.org/api/_as_gen/matplotlib.pyplot.savefig.html|my_page.savefig(...)]] to save a figure | ||
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| * ''my_page.savefig('my_plot.png', dpi=200, transparent=True, bbox_inches='tight')'': save the figure to a png file at a higher resolution than the default (default is 100 dots per inch), with a transparent background and no extra space around the figure | * ''my_page.savefig('my_plot.png', dpi=200, transparent=True, bbox_inches='tight')'': save the figure to a png file at a higher resolution than the default (default is 100 dots per inch), with a transparent background and no extra space around the figure | ||
| - **display** the figure and its plots, and **start interacting** (zooming, panning...) with them:\\ ''plt.show()'' | - **display** the figure and its plots, and **start interacting** (zooming, panning...) with them:\\ ''plt.show()'' | ||
| - | - it may be hard to (remember how to) **work with colors //and colorbars//**. Some examples from the [[https://matplotlib.org/gallery/index.html|matplotlib Gallery]] can help you!\\ Note: A **reversed version of each colormap** is available by appending ''_r'' to the name, e.g., ''viridis_r'' | + | - it may be hard to (remember how to) **work with colors //and colorbars//**. Some examples from the [[https://matplotlib.org/stable/gallery/index.html#color|matplotlib Gallery]] can help you!\\ Note: A **reversed version of each colormap** is available by appending ''_r'' to the name, e.g., ''viridis_r'' |
| - | * [[https://matplotlib.org/gallery/specialty_plots/leftventricle_bulleye.html|leftventricle_bulleye.py]]: associating different types of colormaps to a plot and colorbar | + | * [[https://matplotlib.org/stable/gallery/specialty_plots/leftventricle_bulleye.html|leftventricle_bulleye.py]]: associating different types of colormaps to a plot and colorbar |
| * [[https://matplotlib.org/examples/api/colorbar_only.html|colorbar_only.py]]: the different types of colorbars (or plotting only a colorbar) | * [[https://matplotlib.org/examples/api/colorbar_only.html|colorbar_only.py]]: the different types of colorbars (or plotting only a colorbar) | ||
| - | * [[https://matplotlib.org/gallery/color/colormap_reference.html|colormaps_reference.py]]: pre-defined colormaps | + | * [[https://matplotlib.org/stable/gallery/color/colormap_reference.html|colormaps_reference.py]]: pre-defined colormaps |
| - | * [[https://matplotlib.org/gallery/color/named_colors.html|named_colors.py]]: named colors | + | * [[https://matplotlib.org/stable/gallery/color/named_colors.html|named_colors.py]]: named colors |
| * More details about colors and colorbars below, in the [[#useful_matplotlib_reference_pages|Useful matplotlib reference pages]] section and the [[#graphics_related_resources|Graphics related resources]] section | * More details about colors and colorbars below, in the [[#useful_matplotlib_reference_pages|Useful matplotlib reference pages]] section and the [[#graphics_related_resources|Graphics related resources]] section | ||
| - if you don't see a part of what you have plotted, maybe it's hidden behind other elements! Use the [[https://matplotlib.org/examples/pylab_examples/zorder_demo.html|zorder parameter]] to explicitly **specify the plotting order/layers/depth** | - if you don't see a part of what you have plotted, maybe it's hidden behind other elements! Use the [[https://matplotlib.org/examples/pylab_examples/zorder_demo.html|zorder parameter]] to explicitly **specify the plotting order/layers/depth** | ||
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| * [[https://stackoverflow.com/questions/35479508/cartopy-set-xlabel-set-ylabel-not-ticklabels|Trick source]] | * [[https://stackoverflow.com/questions/35479508/cartopy-set-xlabel-set-ylabel-not-ticklabels|Trick source]] | ||
| * Trick needs to be used with ''cartopy 0.17.0''\\ Remember to update/remove this information in the future | * Trick needs to be used with ''cartopy 0.17.0''\\ Remember to update/remove this information in the future | ||
| - | * Major (and minor) **tick marks location**: ''my_plot.set_xticks(x_ticks_values, minor=False)'' | + | * Major (and minor) **tick marks location**: ''my_plot.set_xticks(x_ticks_values, minor=False)'' ([[https://matplotlib.org/stable/api/_as_gen/matplotlib.axes.Axes.set_xticks.html|set_xticks]]) |
| * Use an empty list if you don't want tick marks: ''my_plot.set_xticks([])'' | * Use an empty list if you don't want tick marks: ''my_plot.set_xticks([])'' | ||
| - | * **Tick labels** (if you don't want the default values): ''my_plot.set_xticklabels(x_ticks_labels, minor=False, fontsize=ticklabels_fontsize)'' | + | * **Tick labels**: ''my_plot.set_xticklabels(x_tick_labels, minor=False, fontsize=ticklabels_fontsize)'' ([[https://matplotlib.org/stable/api/_as_gen/matplotlib.axes.Axes.set_xticklabels.html|set_xticklabels]]) |
| - | * ''x_ticks_labels'' is a list of strings that has the same length as ''x_ticks_values''. Use an empty string in the positions where you don't want a label | + | * If you do not specify labels, the //default labels// will just be the values specifying the ticks' location |
| + | * ''x_tick_labels'' is a list of strings that has the same length as ''x_ticks_values''.\\ Use an empty string in the positions where you don't want a label | ||
| + | * The default numerical labels may be too long, due to numerical approximations. You can try to explicitly round the values, or generate correct label strings from the values\\ <code>>>> x_tick_values = np.arange(0, 1, 0.2) | ||
| + | >>> x_tick_values.tolist() | ||
| + | [0.0, 0.2, 0.4, 0.6000000000000001, 0.8] | ||
| + | >>> x_tick_values.round(decimals=1).tolist() | ||
| + | [0.0, 0.2, 0.4, 0.6, 0.8] | ||
| + | >>> x_tick_labels = [ '%.1f' % (t_val,) for t_val in x_tick_values ] | ||
| + | >>> x_tick_labels | ||
| + | ['0.0', '0.2', '0.4', '0.6', '0.8'] | ||
| + | >>> x_tick_labels[0] = 'START' | ||
| + | >>> x_tick_labels[-1] = 'END' | ||
| + | >>> x_tick_labels | ||
| + | ['START', '0.2', '0.4', '0.6', 'END'] | ||
| + | </code> | ||
| + | * You can also use fancy [[https://matplotlib.org/stable/gallery/ticks_and_spines/tick-formatters.html|tick formatters]] | ||
| * Many more options for ticks, labels, orientation, ... | * Many more options for ticks, labels, orientation, ... | ||
| * **Grid lines**: | * **Grid lines**: | ||
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| * [[https://matplotlib.org/stable/gallery/text_labels_and_annotations/titles_demo.html|Title and labels positions demo]] | * [[https://matplotlib.org/stable/gallery/text_labels_and_annotations/titles_demo.html|Title and labels positions demo]] | ||
| * ''fontsize'': size in points, or (better!) string specifying a relative size (''xx-small'', ''x-small'', ''small'', ''medium'', ''large'', ''x-large'', ''xx-large'') | * ''fontsize'': size in points, or (better!) string specifying a relative size (''xx-small'', ''x-small'', ''small'', ''medium'', ''large'', ''x-large'', ''xx-large'') | ||
| - | * [[https://matplotlib.org/api/text_api.html#matplotlib.text.Text|all the text properties]] | + | * [[https://matplotlib.org/stable/api/text_api.html|all the text properties]] |
| - | * [[https://matplotlib.org/api/pyplot_api.html#matplotlib.pyplot.legend|legend(...)]] ([[https://matplotlib.org/examples/pylab_examples/legend_demo3.html|legend demo]], [[https://matplotlib.org/users/legend_guide.html|advanced legend guide]]) | + | * [[https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.legend.html|legend(...)]] ([[https://matplotlib.org/stable/gallery/text_labels_and_annotations/legend_demo.html|legend demo]], [[https://matplotlib.org/stable/tutorials/intermediate/legend_guide.html|advanced legend guide]]) |
| * The legend will //show// the lines (or other objects) that were associated with a //label// with the ''label='' keyword when creating/updating a plot | * The legend will //show// the lines (or other objects) that were associated with a //label// with the ''label='' keyword when creating/updating a plot | ||
| * If there are some elements of a plot that you do not want to associate with a legend (e.g. there are several lines with the same color and markers, but you want to plot the legend only once), do not specify a ''label='' keyword for these elements, or add a ''_'' at the front of the label strings | * If there are some elements of a plot that you do not want to associate with a legend (e.g. there are several lines with the same color and markers, but you want to plot the legend only once), do not specify a ''label='' keyword for these elements, or add a ''_'' at the front of the label strings | ||
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| plt.show()</code> | plt.show()</code> | ||
| - | Note: see also [[https://matplotlib.org/gallery/user_interfaces/canvasagg.html|CanvasAgg demo]] for a pure offline plot, and [[https://matplotlib.org/faq/howto_faq.html?highlight=web#howto-webapp|How to use Matplotlib in a web application server]]. But the code above is much easier! | + | Note: see also [[https://matplotlib.org/stable/gallery/user_interfaces/canvasagg.html|CanvasAgg demo]] for a pure offline plot, and [[https://matplotlib.org/faq/howto_faq.html?highlight=web#howto-webapp|How to use Matplotlib in a web application server]]. But the code above is much easier! |
| ==== Specifying the background color of a plot ==== | ==== Specifying the background color of a plot ==== | ||
other/python/matplotlib_by_jyp.txt · Last modified: 2023/10/26 08:39 by jypeter
