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"""
***********
Usage Guide
***********
This tutorial covers some basic usage patterns and best-practices to
help you get started with Matplotlib.
"""
# sphinx_gallery_thumbnail_number = 3
import matplotlib.pyplot as plt
import numpy as np
##############################################################################
#
# A simple example
# ================
#
# Matplotlib graphs your data on `~.figure.Figure`\s (i.e., windows, Jupyter
# widgets, etc.), each of which can contain one or more `~.axes.Axes` (i.e., an
# area where points can be specified in terms of x-y coordinates, or theta-r
# in a polar plot, or x-y-z in a 3D plot, etc.). The simplest way of
# creating a figure with an axes is using `.pyplot.subplots`. We can then use
# `.Axes.plot` to draw some data on the axes:
fig, ax = plt.subplots() # Create a figure containing a single axes.
ax.plot([1, 2, 3, 4], [1, 4, 2, 3]) # Plot some data on the axes.
###############################################################################
# Many other plotting libraries or languages do not require you to explicitly
# create an axes. For example, in MATLAB, one can just do
#
# .. code-block:: matlab
#
# plot([1, 2, 3, 4], [1, 4, 2, 3]) % MATLAB plot.
#
# and get the desired graph.
#
# In fact, you can do the same in Matplotlib: for each `~.axes.Axes` graphing
# method, there is a corresponding function in the :mod:`matplotlib.pyplot`
# module that performs that plot on the "current" axes, creating that axes (and
# its parent figure) if they don't exist yet. So, the previous example can be
# written more shortly as
plt.plot([1, 2, 3, 4], [1, 4, 2, 3]) # Matplotlib plot.
###############################################################################
# .. _figure_parts:
#
# Parts of a Figure
# =================
#
# Now, let's have a deeper look at the components of a Matplotlib figure.
#
# .. image:: ../../_static/anatomy.png
#
# :class:`~matplotlib.figure.Figure`
# ----------------------------------
#
# The **whole** figure. The figure keeps
# track of all the child :class:`~matplotlib.axes.Axes`, a smattering of
# 'special' artists (titles, figure legends, etc), and the **canvas**.
# (Don't worry too much about the canvas, it is crucial as it is the
# object that actually does the drawing to get you your plot, but as the
# user it is more-or-less invisible to you). A figure can contain any
# number of :class:`~matplotlib.axes.Axes`, but will typically have
# at least one.
#
# The easiest way to create a new figure is with pyplot::
#
# fig = plt.figure() # an empty figure with no Axes
# fig, ax = plt.subplots() # a figure with a single Axes
# fig, axs = plt.subplots(2, 2) # a figure with a 2x2 grid of Axes
#
# It's convenient to create the axes together with the figure, but you can
# also add axes later on, allowing for more complex axes layouts.
#
# :class:`~matplotlib.axes.Axes`
# ------------------------------
#
# This is what you think of as 'a plot', it is the region of the image
# with the data space. A given figure
# can contain many Axes, but a given :class:`~matplotlib.axes.Axes`
# object can only be in one :class:`~matplotlib.figure.Figure`. The
# Axes contains two (or three in the case of 3D)
# :class:`~matplotlib.axis.Axis` objects (be aware of the difference
# between **Axes** and **Axis**) which take care of the data limits (the
# data limits can also be controlled via the :meth:`.axes.Axes.set_xlim` and
# :meth:`.axes.Axes.set_ylim` methods). Each :class:`~.axes.Axes` has a title
# (set via :meth:`~matplotlib.axes.Axes.set_title`), an x-label (set via
# :meth:`~matplotlib.axes.Axes.set_xlabel`), and a y-label set via
# :meth:`~matplotlib.axes.Axes.set_ylabel`).
#
# The :class:`~.axes.Axes` class and its member functions are the primary entry
# point to working with the OO interface.
#
# :class:`~matplotlib.axis.Axis`
# ------------------------------
#
# These are the number-line-like objects. They take
# care of setting the graph limits and generating the ticks (the marks
# on the axis) and ticklabels (strings labeling the ticks). The location of
# the ticks is determined by a `~matplotlib.ticker.Locator` object and the
# ticklabel strings are formatted by a `~matplotlib.ticker.Formatter`. The
# combination of the correct `.Locator` and `.Formatter` gives very fine
# control over the tick locations and labels.
#
# :class:`~matplotlib.artist.Artist`
# ----------------------------------
#
# Basically, everything you can see on the figure is an artist (even the
# `.Figure`, `Axes <.axes.Axes>`, and `~.axis.Axis` objects). This includes
# `.Text` objects, `.Line2D` objects, :mod:`.collections` objects, `.Patch`
# objects ... (you get the idea). When the figure is rendered, all of the
# artists are drawn to the **canvas**. Most Artists are tied to an Axes; such
# an Artist cannot be shared by multiple Axes, or moved from one to another.
#
# .. _input_types:
#
# Types of inputs to plotting functions
# =====================================
#
# All of plotting functions expect `numpy.array` or `numpy.ma.masked_array` as
# input. Classes that are 'array-like' such as `pandas` data objects
# and `numpy.matrix` may or may not work as intended. It is best to
# convert these to `numpy.array` objects prior to plotting.
#
# For example, to convert a `pandas.DataFrame` ::
#
# a = pandas.DataFrame(np.random.rand(4, 5), columns = list('abcde'))
# a_asarray = a.values
#
# and to convert a `numpy.matrix` ::
#
# b = np.matrix([[1, 2], [3, 4]])
# b_asarray = np.asarray(b)
#
# .. _coding_styles:
#
# The object-oriented interface and the pyplot interface
# ======================================================
#
# As noted above, there are essentially two ways to use Matplotlib:
#
# - Explicitly create figures and axes, and call methods on them (the
# "object-oriented (OO) style").
# - Rely on pyplot to automatically create and manage the figures and axes, and
# use pyplot functions for plotting.
#
# So one can do (OO-style)
x = np.linspace(0, 2, 100)
# Note that even in the OO-style, we use `.pyplot.figure` to create the figure.
fig, ax = plt.subplots() # Create a figure and an axes.
ax.plot(x, x, label='linear') # Plot some data on the axes.
ax.plot(x, x**2, label='quadratic') # Plot more data on the axes...
ax.plot(x, x**3, label='cubic') # ... and some more.
ax.set_xlabel('x label') # Add an x-label to the axes.
ax.set_ylabel('y label') # Add a y-label to the axes.
ax.set_title("Simple Plot") # Add a title to the axes.
ax.legend() # Add a legend.
###############################################################################
# or (pyplot-style)
x = np.linspace(0, 2, 100)
plt.plot(x, x, label='linear') # Plot some data on the (implicit) axes.
plt.plot(x, x**2, label='quadratic') # etc.
plt.plot(x, x**3, label='cubic')
plt.xlabel('x label')
plt.ylabel('y label')
plt.title("Simple Plot")
plt.legend()
###############################################################################
# In addition, there is a third approach, for the case when embedding
# Matplotlib in a GUI application, which completely drops pyplot, even for
# figure creation. We won't discuss it here; see the corresponding section in
# the gallery for more info (:ref:`user_interfaces`).
#
# Matplotlib's documentation and examples use both the OO and the pyplot
# approaches (which are equally powerful), and you should feel free to use
# either (however, it is preferable pick one of them and stick to it, instead
# of mixing them). In general, we suggest to restrict pyplot to interactive
# plotting (e.g., in a Jupyter notebook), and to prefer the OO-style for
# non-interactive plotting (in functions and scripts that are intended to be
# reused as part of a larger project).
#
# .. note::
#
# In older examples, you may find examples that instead used the so-called
# ``pylab`` interface, via ``from pylab import *``. This star-import
# imports everything both from pyplot and from :mod:`numpy`, so that one
# could do ::
#
# x = linspace(0, 2, 100)
# plot(x, x, label='linear')
# ...
#
# for an even more MATLAB-like style. This approach is strongly discouraged
# nowadays and deprecated. It is only mentioned here because you may still
# encounter it in the wild.
#
# Typically one finds oneself making the same plots over and over
# again, but with different data sets, which leads to needing to write
# specialized functions to do the plotting. The recommended function
# signature is something like:
def my_plotter(ax, data1, data2, param_dict):
"""
A helper function to make a graph
Parameters
----------
ax : Axes
The axes to draw to
data1 : array
The x data
data2 : array
The y data
param_dict : dict
Dictionary of kwargs to pass to ax.plot
Returns
-------
out : list
list of artists added
"""
out = ax.plot(data1, data2, **param_dict)
return out
###############################################################################
# which you would then use as:
data1, data2, data3, data4 = np.random.randn(4, 100)
fig, ax = plt.subplots(1, 1)
my_plotter(ax, data1, data2, {'marker': 'x'})
###############################################################################
# or if you wanted to have 2 sub-plots:
fig, (ax1, ax2) = plt.subplots(1, 2)
my_plotter(ax1, data1, data2, {'marker': 'x'})
my_plotter(ax2, data3, data4, {'marker': 'o'})
###############################################################################
# For these simple examples this style seems like overkill, however
# once the graphs get slightly more complex it pays off.
#
#
# .. _backends:
#
# Backends
# ========
#
# .. _what-is-a-backend:
#
# What is a backend?
# ------------------
#
# A lot of documentation on the website and in the mailing lists refers
# to the "backend" and many new users are confused by this term.
# Matplotlib targets many different use cases and output formats. Some
# people use Matplotlib interactively from the python shell and have
# plotting windows pop up when they type commands. Some people run
# `Jupyter <https://jupyter.org>`_ notebooks and draw inline plots for
# quick data analysis. Others embed Matplotlib into graphical user
# interfaces like PyQt or PyGObject to build rich applications. Some
# people use Matplotlib in batch scripts to generate postscript images
# from numerical simulations, and still others run web application
# servers to dynamically serve up graphs.
#
# To support all of these use cases, Matplotlib can target different
# outputs, and each of these capabilities is called a backend; the
# "frontend" is the user facing code, i.e., the plotting code, whereas the
# "backend" does all the hard work behind-the-scenes to make the figure.
# There are two types of backends: user interface backends (for use in
# PyQt/PySide, PyGObject, Tkinter, wxPython, or macOS/Cocoa); also referred to
# as "interactive backends") and hardcopy backends to make image files
# (PNG, SVG, PDF, PS; also referred to as "non-interactive backends").
#
# Selecting a backend
# -------------------
#
# There are three ways to configure your backend:
#
# 1. The :rc:`backend` parameter in your :file:`matplotlibrc` file
# 2. The :envvar:`MPLBACKEND` environment variable
# 3. The function :func:`matplotlib.use`
#
# A more detailed description is given below.
#
# If multiple of these are configurations are present, the last one from the
# list takes precedence; e.g. calling :func:`matplotlib.use()` will override
# the setting in your :file:`matplotlibrc`.
#
# If no backend is explicitly set, Matplotlib automatically detects a usable
# backend based on what is available on your system and on whether a GUI event
# loop is already running. On Linux, if the environment variable
# :envvar:`DISPLAY` is unset, the "event loop" is identified as "headless",
# which causes a fallback to a noninteractive backend (agg); in all other
# cases, an interactive backend is preferred (usually, at least tkagg will be
# available).
#
# Here is a detailed description of the configuration methods:
#
# #. Setting :rc:`backend` in your :file:`matplotlibrc` file::
#
# backend : qt5agg # use pyqt5 with antigrain (agg) rendering
#
# See also :doc:`/tutorials/introductory/customizing`.
#
# #. Setting the :envvar:`MPLBACKEND` environment variable:
#
# You can set the environment variable either for your current shell or for
# a single script.
#
# On Unix::
#
# > export MPLBACKEND=qt5agg
# > python simple_plot.py
#
# > MPLBACKEND=qt5agg python simple_plot.py
#
# On Windows, only the former is possible::
#
# > set MPLBACKEND=qt5agg
# > python simple_plot.py
#
# Setting this environment variable will override the ``backend`` parameter
# in *any* :file:`matplotlibrc`, even if there is a :file:`matplotlibrc` in
# your current working directory. Therefore, setting :envvar:`MPLBACKEND`
# globally, e.g. in your :file:`.bashrc` or :file:`.profile`, is discouraged
# as it might lead to counter-intuitive behavior.
#
# #. If your script depends on a specific backend you can use the function
# :func:`matplotlib.use`::
#
# import matplotlib
# matplotlib.use('qt5agg')
#
# This should be done before any figure is created, otherwise Matplotlib may
# fail to switch the backend and raise an ImportError.
#
# Using `~matplotlib.use` will require changes in your code if users want to
# use a different backend. Therefore, you should avoid explicitly calling
# `~matplotlib.use` unless absolutely necessary.
#
# .. _the-builtin-backends:
#
# The builtin backends
# --------------------
#
# By default, Matplotlib should automatically select a default backend which
# allows both interactive work and plotting from scripts, with output to the
# screen and/or to a file, so at least initially, you will not need to worry
# about the backend. The most common exception is if your Python distribution
# comes without :mod:`tkinter` and you have no other GUI toolkit installed.
# This happens on certain Linux distributions, where you need to install a
# Linux package named ``python-tk`` (or similar).
#
# If, however, you want to write graphical user interfaces, or a web
# application server
# (:doc:`/gallery/user_interfaces/web_application_server_sgskip`), or need a
# better understanding of what is going on, read on. To make things a little
# more customizable for graphical user interfaces, Matplotlib separates
# the concept of the renderer (the thing that actually does the drawing)
# from the canvas (the place where the drawing goes). The canonical
# renderer for user interfaces is ``Agg`` which uses the `Anti-Grain
# Geometry`_ C++ library to make a raster (pixel) image of the figure; it
# is used by the ``Qt5Agg``, ``Qt4Agg``, ``GTK3Agg``, ``wxAgg``, ``TkAgg``, and
# ``macosx`` backends. An alternative renderer is based on the Cairo library,
# used by ``Qt5Cairo``, ``Qt4Cairo``, etc.
#
# For the rendering engines, one can also distinguish between `vector
# <https://en.wikipedia.org/wiki/Vector_graphics>`_ or `raster
# <https://en.wikipedia.org/wiki/Raster_graphics>`_ renderers. Vector
# graphics languages issue drawing commands like "draw a line from this
# point to this point" and hence are scale free, and raster backends
# generate a pixel representation of the line whose accuracy depends on a
# DPI setting.
#
# Here is a summary of the Matplotlib renderers (there is an eponymous
# backend for each; these are *non-interactive backends*, capable of
# writing to a file):
#
# ======== ========= =======================================================
# Renderer Filetypes Description
# ======== ========= =======================================================
# AGG png raster_ graphics -- high quality images using the
# `Anti-Grain Geometry`_ engine
# PDF pdf vector_ graphics -- `Portable Document Format`_
# PS ps, eps vector_ graphics -- Postscript_ output
# SVG svg vector_ graphics -- `Scalable Vector Graphics`_
# PGF pgf, pdf vector_ graphics -- using the pgf_ package
# Cairo png, ps, raster_ or vector_ graphics -- using the Cairo_ library
# pdf, svg
# ======== ========= =======================================================
#
# To save plots using the non-interactive backends, use the
# ``matplotlib.pyplot.savefig('filename')`` method.
#
# And here are the user interfaces and renderer combinations supported;
# these are *interactive backends*, capable of displaying to the screen
# and of using appropriate renderers from the table above to write to
# a file:
#
# ========= ================================================================
# Backend Description
# ========= ================================================================
# Qt5Agg Agg rendering in a Qt5_ canvas (requires PyQt5_). This
# backend can be activated in IPython with ``%matplotlib qt5``.
# ipympl Agg rendering embedded in a Jupyter widget. (requires ipympl).
# This backend can be enabled in a Jupyter notebook with
# ``%matplotlib ipympl``.
# GTK3Agg Agg rendering to a GTK_ 3.x canvas (requires PyGObject_,
# and pycairo_ or cairocffi_). This backend can be activated in
# IPython with ``%matplotlib gtk3``.
# macosx Agg rendering into a Cocoa canvas in OSX. This backend can be
# activated in IPython with ``%matplotlib osx``.
# TkAgg Agg rendering to a Tk_ canvas (requires TkInter_). This
# backend can be activated in IPython with ``%matplotlib tk``.
# nbAgg Embed an interactive figure in a Jupyter classic notebook. This
# backend can be enabled in Jupyter notebooks via
# ``%matplotlib notebook``.
# WebAgg On ``show()`` will start a tornado server with an interactive
# figure.
# GTK3Cairo Cairo rendering to a GTK_ 3.x canvas (requires PyGObject_,
# and pycairo_ or cairocffi_).
# Qt4Agg Agg rendering to a Qt4_ canvas (requires PyQt4_ or
# ``pyside``). This backend can be activated in IPython with
# ``%matplotlib qt4``.
# wxAgg Agg rendering to a wxWidgets_ canvas (requires wxPython_ 4).
# This backend can be activated in IPython with ``%matplotlib wx``.
# ========= ================================================================
#
# .. note::
# The names of builtin backends case-insensitive; e.g., 'Qt5Agg' and
# 'qt5agg' are equivalent.
#
# .. _`Anti-Grain Geometry`: http://antigrain.com/
# .. _`Portable Document Format`: https://en.wikipedia.org/wiki/Portable_Document_Format
# .. _Postscript: https://en.wikipedia.org/wiki/PostScript
# .. _`Scalable Vector Graphics`: https://en.wikipedia.org/wiki/Scalable_Vector_Graphics
# .. _pgf: https://ctan.org/pkg/pgf
# .. _Cairo: https://www.cairographics.org
# .. _PyGObject: https://wiki.gnome.org/action/show/Projects/PyGObject
# .. _pycairo: https://www.cairographics.org/pycairo/
# .. _cairocffi: https://pythonhosted.org/cairocffi/
# .. _wxPython: https://www.wxpython.org/
# .. _TkInter: https://docs.python.org/3/library/tk.html
# .. _PyQt4: https://riverbankcomputing.com/software/pyqt/intro
# .. _PyQt5: https://riverbankcomputing.com/software/pyqt/intro
# .. _Qt5: https://doc.qt.io/qt-5/index.html
# .. _GTK: https://www.gtk.org/
# .. _Tk: https://www.tcl.tk/
# .. _Qt4: https://doc.qt.io/archives/qt-4.8/index.html
# .. _wxWidgets: https://www.wxwidgets.org/
#
# ipympl
# ^^^^^^
#
# The Jupyter widget ecosystem is moving too fast to support directly in
# Matplotlib. To install ipympl
#
# .. code-block:: bash
#
# pip install ipympl
# jupyter nbextension enable --py --sys-prefix ipympl
#
# or
#
# .. code-block:: bash
#
# conda install ipympl -c conda-forge
#
# See `jupyter-matplotlib <https://github.com/matplotlib/jupyter-matplotlib>`__
# for more details.
#
# .. _QT_API-usage:
#
# How do I select PyQt4 or PySide?
# ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
#
# The :envvar:`QT_API` environment variable can be set to either ``pyqt`` or
# ``pyside`` to use ``PyQt4`` or ``PySide``, respectively.
#
# Since the default value for the bindings to be used is ``PyQt4``, Matplotlib
# first tries to import it. If the import fails, it tries to import ``PySide``.
#
# Using non-builtin backends
# --------------------------
# More generally, any importable backend can be selected by using any of the
# methods above. If ``name.of.the.backend`` is the module containing the
# backend, use ``module://name.of.the.backend`` as the backend name, e.g.
# ``matplotlib.use('module://name.of.the.backend')``.
#
#
# .. _interactive-mode:
#
# What is interactive mode?
# =========================
#
# Use of an interactive backend (see :ref:`what-is-a-backend`)
# permits--but does not by itself require or ensure--plotting
# to the screen. Whether and when plotting to the screen occurs,
# and whether a script or shell session continues after a plot
# is drawn on the screen, depends on the functions and methods
# that are called, and on a state variable that determines whether
# Matplotlib is in "interactive mode". The default Boolean value is set
# by the :file:`matplotlibrc` file, and may be customized like any other
# configuration parameter (see :doc:`/tutorials/introductory/customizing`). It
# may also be set via :func:`matplotlib.interactive`, and its
# value may be queried via :func:`matplotlib.is_interactive`. Turning
# interactive mode on and off in the middle of a stream of plotting
# commands, whether in a script or in a shell, is rarely needed
# and potentially confusing. In the following, we will assume all
# plotting is done with interactive mode either on or off.
#
# .. note::
# Major changes related to interactivity, and in particular the
# role and behavior of :func:`~matplotlib.pyplot.show`, were made in the
# transition to Matplotlib version 1.0, and bugs were fixed in
# 1.0.1. Here we describe the version 1.0.1 behavior for the
# primary interactive backends, with the partial exception of
# *macosx*.
#
# Interactive mode may also be turned on via :func:`matplotlib.pyplot.ion`,
# and turned off via :func:`matplotlib.pyplot.ioff`.
#
# .. note::
# Interactive mode works with suitable backends in ipython and in
# the ordinary python shell, but it does *not* work in the IDLE IDE.
# If the default backend does not support interactivity, an interactive
# backend can be explicitly activated using any of the methods discussed
# in `What is a backend?`_.
#
#
# Interactive example
# --------------------
#
# From an ordinary python prompt, or after invoking ipython with no options,
# try this::
#
# import matplotlib.pyplot as plt
# plt.ion()
# plt.plot([1.6, 2.7])
#
# This will pop up a plot window. Your terminal prompt will remain active, so
# that you can type additional commands such as::
#
# plt.title("interactive test")
# plt.xlabel("index")
#
# On most interactive backends, the figure window will also be updated if you
# change it via the object-oriented interface. E.g. get a reference to the
# `~matplotlib.axes.Axes` instance, and call a method of that instance::
#
# ax = plt.gca()
# ax.plot([3.1, 2.2])
#
# If you are using certain backends (like ``macosx``), or an older version
# of Matplotlib, you may not see the new line added to the plot immediately.
# In this case, you need to explicitly call :func:`~matplotlib.pyplot.draw`
# in order to update the plot::
#
# plt.draw()
#
#
# Non-interactive example
# -----------------------
#
# Start a fresh session as in the previous example, but now
# turn interactive mode off::
#
# import matplotlib.pyplot as plt
# plt.ioff()
# plt.plot([1.6, 2.7])
#
# Nothing happened--or at least nothing has shown up on the
# screen (unless you are using *macosx* backend, which is
# anomalous). To make the plot appear, you need to do this::
#
# plt.show()
#
# Now you see the plot, but your terminal command line is
# unresponsive; `.pyplot.show()` *blocks* the input
# of additional commands until you manually kill the plot
# window.
#
# What good is this--being forced to use a blocking function?
# Suppose you need a script that plots the contents of a file
# to the screen. You want to look at that plot, and then end
# the script. Without some blocking command such as ``show()``, the
# script would flash up the plot and then end immediately,
# leaving nothing on the screen.
#
# In addition, non-interactive mode delays all drawing until
# ``show()`` is called; this is more efficient than redrawing
# the plot each time a line in the script adds a new feature.
#
# Prior to version 1.0, ``show()`` generally could not be called
# more than once in a single script (although sometimes one
# could get away with it); for version 1.0.1 and above, this
# restriction is lifted, so one can write a script like this::
#
# import numpy as np
# import matplotlib.pyplot as plt
#
# plt.ioff()
# for i in range(3):
# plt.plot(np.random.rand(10))
# plt.show()
#
# This makes three plots, one at a time. I.e., the second plot will show up
# once the first plot is closed.
#
# Summary
# -------
#
# In interactive mode, pyplot functions automatically draw
# to the screen.
#
# When plotting interactively, if using
# object method calls in addition to pyplot functions, then
# call :func:`~matplotlib.pyplot.draw` whenever you want to
# refresh the plot.
#
# Use non-interactive mode in scripts in which you want to
# generate one or more figures and display them before ending
# or generating a new set of figures. In that case, use
# :func:`~matplotlib.pyplot.show` to display the figure(s) and
# to block execution until you have manually destroyed them.
#
# .. _performance:
#
# Performance
# ===========
#
# Whether exploring data in interactive mode or programmatically
# saving lots of plots, rendering performance can be a painful
# bottleneck in your pipeline. Matplotlib provides a couple
# ways to greatly reduce rendering time at the cost of a slight
# change (to a settable tolerance) in your plot's appearance.
# The methods available to reduce rendering time depend on the
# type of plot that is being created.
#
# Line segment simplification
# ---------------------------
#
# For plots that have line segments (e.g. typical line plots, outlines
# of polygons, etc.), rendering performance can be controlled by
# :rc:`path.simplify` and :rc:`path.simplify_threshold`, which
# can be defined e.g. in the :file:`matplotlibrc` file (see
# :doc:`/tutorials/introductory/customizing` for more information about
# the :file:`matplotlibrc` file). :rc:`path.simplify` is a boolean
# indicating whether or not line segments are simplified at all.
# :rc:`path.simplify_threshold` controls how much line segments are simplified;
# higher thresholds result in quicker rendering.
#
# The following script will first display the data without any
# simplification, and then display the same data with simplification.
# Try interacting with both of them::
#
# import numpy as np
# import matplotlib.pyplot as plt
# import matplotlib as mpl
#
# # Setup, and create the data to plot
# y = np.random.rand(100000)
# y[50000:] *= 2
# y[np.geomspace(10, 50000, 400).astype(int)] = -1
# mpl.rcParams['path.simplify'] = True
#
# mpl.rcParams['path.simplify_threshold'] = 0.0
# plt.plot(y)
# plt.show()
#
# mpl.rcParams['path.simplify_threshold'] = 1.0
# plt.plot(y)
# plt.show()
#
# Matplotlib currently defaults to a conservative simplification
# threshold of ``1/9``. If you want to change your default settings
# to use a different value, you can change your :file:`matplotlibrc`
# file. Alternatively, you could create a new style for
# interactive plotting (with maximal simplification) and another
# style for publication quality plotting (with minimal
# simplification) and activate them as necessary. See
# :doc:`/tutorials/introductory/customizing` for
# instructions on how to perform these actions.
#
# The simplification works by iteratively merging line segments
# into a single vector until the next line segment's perpendicular
# distance to the vector (measured in display-coordinate space)
# is greater than the ``path.simplify_threshold`` parameter.
#
# .. note::
# Changes related to how line segments are simplified were made
# in version 2.1. Rendering time will still be improved by these
# parameters prior to 2.1, but rendering time for some kinds of
# data will be vastly improved in versions 2.1 and greater.
#
# Marker simplification
# ---------------------
#
# Markers can also be simplified, albeit less robustly than
# line segments. Marker simplification is only available
# to :class:`~matplotlib.lines.Line2D` objects (through the
# ``markevery`` property). Wherever
# :class:`~matplotlib.lines.Line2D` construction parameters
# are passed through, such as
# :func:`matplotlib.pyplot.plot` and
# :meth:`matplotlib.axes.Axes.plot`, the ``markevery``
# parameter can be used::
#
# plt.plot(x, y, markevery=10)
#
# The ``markevery`` argument allows for naive subsampling, or an
# attempt at evenly spaced (along the *x* axis) sampling. See the
# :doc:`/gallery/lines_bars_and_markers/markevery_demo`
# for more information.
#
# Splitting lines into smaller chunks
# -----------------------------------
#
# If you are using the Agg backend (see :ref:`what-is-a-backend`),
# then you can make use of :rc:`agg.path.chunksize`
# This allows you to specify a chunk size, and any lines with
# greater than that many vertices will be split into multiple
# lines, each of which has no more than ``agg.path.chunksize``
# many vertices. (Unless ``agg.path.chunksize`` is zero, in
# which case there is no chunking.) For some kind of data,
# chunking the line up into reasonable sizes can greatly
# decrease rendering time.
#
# The following script will first display the data without any
# chunk size restriction, and then display the same data with
# a chunk size of 10,000. The difference can best be seen when
# the figures are large, try maximizing the GUI and then
# interacting with them::
#
# import numpy as np
# import matplotlib.pyplot as plt
# import matplotlib as mpl
# mpl.rcParams['path.simplify_threshold'] = 1.0
#
# # Setup, and create the data to plot
# y = np.random.rand(100000)
# y[50000:] *= 2
# y[np.geomspace(10, 50000, 400).astype(int)] = -1
# mpl.rcParams['path.simplify'] = True
#
# mpl.rcParams['agg.path.chunksize'] = 0
# plt.plot(y)
# plt.show()
#
# mpl.rcParams['agg.path.chunksize'] = 10000
# plt.plot(y)
# plt.show()
#
# Legends
# -------
#
# The default legend behavior for axes attempts to find the location
# that covers the fewest data points (``loc='best'``). This can be a
# very expensive computation if there are lots of data points. In
# this case, you may want to provide a specific location.
#
# Using the *fast* style
# ----------------------
#
# The *fast* style can be used to automatically set
# simplification and chunking parameters to reasonable
# settings to speed up plotting large amounts of data.
# It can be used simply by running::
#
# import matplotlib.style as mplstyle
# mplstyle.use('fast')
#
# It is very lightweight, so it plays nicely with other
# styles, just make sure the fast style is applied last
# so that other styles do not overwrite the settings::
#
# mplstyle.use(['dark_background', 'ggplot', 'fast'])
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