other:python:matplotlib_by_jyp
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other:python:matplotlib_by_jyp [2019/09/05 14:38] jypeter Some changes |
other:python:matplotlib_by_jyp [2020/02/11 11:00] jypeter [Starting (and more) with matplotlib] |
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| ====== Working with matplotlib (JYP version) ====== | ====== Working with matplotlib (JYP version) ====== | ||
| + | **Summary**: there are lots of python libraries that you can use for plotting, but Matplotlib has become a //de facto// standard | ||
| - | Summary: there are lots of python libraries that you can use for plotting, but Matplotlib has become a //de facto// standard | + | You can get more **information about python** on the [[other:python:jyp_steps|JYP's recommended steps for learning python]] page. |
| - | Where: [[http://matplotlib.org|Matplotlib web site]] | + | You can get more **information on plotting maps** in the [[other:python:jyp_steps#cartopy_iris|Cartopy + Iris section]] and the [[other:python:jyp_steps#basemap|basemap section]], with examples on the [[other:python:maps_by_jyp|JYP's map room]] page. Note: there will be no python3 support in basemap, and basemap is being slowly replaced by cartopy |
| - | Help on //stack overflow//: [[https://stackoverflow.com/questions/tagged/matplotlib|matplotlib help]] | + | matplotlib official website: [[http://matplotlib.org|Matplotlib web site]] |
| + | |||
| + | matplotlib help on //stack overflow//: [[https://stackoverflow.com/questions/tagged/matplotlib|matplotlib help]] | ||
| ===== Starting (and more) with matplotlib ===== | ===== Starting (and more) with matplotlib ===== | ||
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| There are lots of online tutorials that often don't show much more than a simple scatter plot with basic page setup. | There are lots of online tutorials that often don't show much more than a simple scatter plot with basic page setup. | ||
| - | This page will hopefully give you some keeys to become (progressively) a matplotlib power user. | + | This page will hopefully give you some keys to become (progressively) a matplotlib power user. |
| <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) | ||
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| * later, you may need other matplotlib related modules, for advanced usage | * later, you may need other matplotlib related modules, for advanced usage | ||
| - You need to know some **matplotlib specific vocabulary**: | - You need to know some **matplotlib specific vocabulary**: | ||
| - | * a Matplotlib **//Figure//** (or //canvas//) is a **graphical window** in which you create your plots... | + | * a Matplotlib **//Figure//** (or //canvas//) is a **graphical window** or //page// in which you create your plots... |
| * example: ''my_page = plt.figure()'' | * example: ''my_page = plt.figure()'' | ||
| * if you need several display windows at the same time, create several figures!\\ <code>win_1 = plt.figure() | * if you need several display windows at the same time, create several figures!\\ <code>win_1 = plt.figure() | ||
| win_2 = plt.figure()</code> | win_2 = plt.figure()</code> | ||
| - | * the [[http://matplotlib.org/faq/usage_faq.html#parts-of-a-figure|parts of a figure]] are often positioned in //normalized coordinates//: ''(0, 0)'' is the bottom left of the figure, and ''(1, 1)'' the top right | + | * the [[http://matplotlib.org/faq/usage_faq.html#parts-of-a-figure|parts of a figure]] are usually positioned in //normalized coordinates//: ''(0, 0)'' is the bottom left of the figure, and ''(1, 1)'' is the top right |
| * You don't really specify the **page orientation** (//portrait// or //landscape//) of a plot. If you want a portrait plot, it's up to you to create a plot that will look higher than it is large. The idea is not to worry about this and just check the final resulting plot: create a plot, save it, display the resulting png/pdf and then adjust the creation script | * You don't really specify the **page orientation** (//portrait// or //landscape//) of a plot. If you want a portrait plot, it's up to you to create a plot that will look higher than it is large. The idea is not to worry about this and just check the final resulting plot: create a plot, save it, display the resulting png/pdf and then adjust the creation script | ||
| * If you do have an idea of the layout of what you want to plot, it may be easier to explicitly specify the figure size/ratio at creation time, and then try to //fill// the normalized coordinates space of the figure | * If you do have an idea of the layout of what you want to plot, it may be easier to explicitly specify the figure size/ratio at creation time, and then try to //fill// the normalized coordinates space of the figure | ||
| * ''my_page = plt.figure()'': the ratio of the default figure is ''landscape'', because it is 33% larger than it is high. Creating a default figure will be OK most of the time! | * ''my_page = plt.figure()'': the ratio of the default figure is ''landscape'', because it is 33% larger than it is high. Creating a default figure will be OK most of the time! | ||
| - | * ''my_page = plt.figure(figsize=(width, height))'': create a figure with a custom ratio (sizes are considered to be in inches) | + | * ''my_page = plt.figure(figsize=(width, height))'': create a figure with a custom ratio |
| - | * ''my_page = plt.figure(figsize=(8.3, 11.7))'': create a figure that will theoretically fill an A4 size page in portrait mode (check [[https://www.papersizes.org/a-paper-sizes.htm|Dimensions Of A Series Paper Sizes]] if you need more size details) | + | * The specified ''width'' and ''height'' are supposed to be in inches (1 inch = 2.54 cm) |
| + | * ''my_page = plt.figure(figsize=(8.3, 11.7))'': create a figure that will theoretically fill an A4 size page in portrait mode (check [[https://www.papersizes.org/a-paper-sizes.htm|Dimensions Of A Series Paper Sizes]] if you need more details about standard paper sizes) | ||
| * a Matplotlib **//Axis//** is a **plot** inside a Figure... [[http://matplotlib.org/faq/usage_faq.html#parts-of-a-figure|More details]] | * a Matplotlib **//Axis//** is a **plot** inside a Figure... [[http://matplotlib.org/faq/usage_faq.html#parts-of-a-figure|More details]] | ||
| * reserve space for **one plot** that will use most of the available area of the figure/page: | * reserve space for **one plot** that will use most of the available area of the figure/page: | ||
| - | * ''my_plot = my_page.add_subplot(1, 1, 1)'': syntax is ''add_subplot(nrows, ncols, index)'' | + | * ''my_plot = my_page.add_subplot(1, 1, 1)'' or ''my_plot = my_page.subplot**s**()'' |
| - | * ''my_plot = my_page.subplot**s**()'' | + | * the syntax for **more than one plot** is: ''add_subplot(nrows, ncols, index)'' |
| * create **3 plots on 1 column** (each plot uses the full width of the figure): | * create **3 plots on 1 column** (each plot uses the full width of the figure): | ||
| * <code>top_plot = my_page.add_subplot(3, 1, 1) | * <code>top_plot = my_page.add_subplot(3, 1, 1) | ||
| - | middle_plot = my_page.add_subplot(3, 1, 2) | + | mid_plot = my_page.add_subplot(3, 1, 2) |
| - | bottom_plot = my_page.add_subplot(3, 1, 3)</code> | + | bot_plot = my_page.add_subplot(3, 1, 3)</code> |
| - | * the following method is more efficient than add_subplot when there are lots of plots on a page<code>plot_array = my_page.subplots(3, 1) | + | * creating an //array of plots// with ''subplots'' is **more efficient** than ''add_subplot'' when there are lots of plots on a page<code>plot_array = my_page.subplots(3, 1) |
| + | top_plot = plot_array[0] | ||
| + | mid_plot = plot_array[1] | ||
| + | bot_plot = plot_array[2]</code> | ||
| + | * it is **even more efficient** to create a //figure// and //axes// with a single line: | ||
| + | * one plot on one page: ''my_page, my_plot = **plt**.subplots()'' | ||
| + | * three plots on one A4 portrait page:\\ <code> | ||
| + | my_page, plot_array = plt.subplots(nrows=3, ncols=1, | ||
| + | figsize=(8.3, 11.) # A4 portrait) | ||
| top_plot = plot_array[0] | top_plot = plot_array[0] | ||
| - | middle_plot = plot_array[1] | + | mid_plot = plot_array[1] |
| - | bottom_plot = plot_array[2]</code> | + | bot_plot = plot_array[2] |
| - | * creating a figure and axes with a single line: ''my_page, plot_array = **plt**.subplots(3, 1)'' | + | </code> |
| * use [[https://matplotlib.org/api/_as_gen/matplotlib.figure.Figure.html#matplotlib.figure.Figure.add_axes|my_page.add_axes(...)]] to add an axis in an arbirary location of the page\\ ''my_page.add_axes([left, bottom, width, height])'' | * use [[https://matplotlib.org/api/_as_gen/matplotlib.figure.Figure.html#matplotlib.figure.Figure.add_axes|my_page.add_axes(...)]] to add an axis in an arbirary location of the page\\ ''my_page.add_axes([left, bottom, width, height])'' | ||
| * a Matplotlib **//Artist//** or //Patch// is //something// (e.g a line, a group of markers, text, the legend...) plotted on the Figure/Axis | * a Matplotlib **//Artist//** or //Patch// is //something// (e.g a line, a group of markers, text, the legend...) plotted on the Figure/Axis | ||
other/python/matplotlib_by_jyp.txt · Last modified: 2023/10/26 08:39 by jypeter
