python大佬的可视化工具-Altair
作者:互联网
- 本文再分享一个python交互式可视化工具Altair,Altair的底层是Vega-Lite (基于一种简洁的交互式可视化语法,A Grammar of Interactive Graphics),效果例如:
- Altair的作者为Jake Vanderplas,是一个大佬,之前是华盛顿大学 eScience 学院物理科学研究院院长,现为Google的Software Engineer,热衷于Python, Astronomy和Data Science;同时是一位活跃的开源爱好者,历年的 PyData会议都能见到他的talk,除了Altair外,为Scikit-Learn、Scipy、 Matplotlib、IPython 等著名 Python 程序库做了大量贡献;著有两本高stars书籍Python Data Science Handbook 和A Whirlwind Tour of Python 。
目录
selection、condition、binding使得altair图形能和鼠标更好交互
Layer, HConcat, VConcat, Repeat, Facet助力altair轻松构建复合图形
Chart.resolve_scale(), Chart.resolve_axis(), and Chart.resolve_legend()个性化复合图形
官网:https://altair-viz.github.io/index.html
1、Altair基础图形快速入门
这个小结介绍如何快速的绘制常见的基础图,如“bar”, “circle”, “square”, “tick”,“line”, * “area”, “point”, “rule”, “geoshape”, and “text”等。
pip安装altair
pip install altair vega_datasets -i https://pypi.tuna.tsinghua.edu.cn/simple#国内源加速安装
Altair一步一步绘图
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数据准备
依旧使用鸢尾花iris数据集,数据集介绍见:Python可视化|matplotlib10-绘制散点图scatter
import seaborn as sns
pd_iris = sns.load_dataset("iris")
pd_iris.head(n=5)
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快速绘图
#快速绘图
import altair as alt
import pandas as pd
alt.Chart(pd_iris).mark_point().encode(x='sepal_length',
y='sepal_width',
color='species')
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绘图步骤拆分
由alt.Chart(pd_iris).mark_point().encode(x='sepal_length',y='sepal_width',color='species')这段代码可知,Altair绘图主要用到Chart()方法、mark_*()方法、和encode()方法。
Chart()方法将数据转化为altair.vegalite.v4.api.Chart对象
括号内可设置图像的高度、宽度、背景色等等,详细见:https://altair-viz.github.io/user_guide/generated/toplevel/altair.Chart.html?highlight=chart
mark_*()方法指定要展示的图形,例如绘制散点图mark_point()
mark_*()方法设置图形属性,如颜色color、大小size等
括号内可设置待展示图形的各种属性,以mark_point()设置点颜色为例如下。
encode()方法设置坐标轴的映射
python的Altair脚本转化为JSON
python脚本
import altair as alt
import pandas as pd
data = pd.DataFrame({'x': ['A', 'B', 'C', 'D'], 'y': [1, 2, 1, 2]})
alt.Chart(data).mark_bar().encode(
x='x',
y='y',
)
json脚本点击即可获取
{
"config": {"view": {"continuousWidth": 400, "continuousHeight": 300}},
"data": {"name": "data-39e740acccd9d827d4364cdbd6d37176"},
"mark": "bar",
"encoding": {
"x": {"type": "nominal", "field": "x"},
"y": {"type": "quantitative", "field": "y"}
},
"$schema": "https://vega.github.io/schema/vega-lite/v4.8.1.json",
"datasets": {
"data-39e740acccd9d827d4364cdbd6d37176": [
{"x": "A", "y": 1},
{"x": "B", "y": 2},
{"x": "C", "y": 1},
{"x": "D", "y": 2}
]
}
}
2、Altair复杂图形快速入门
这一节简单介绍更复杂的图形,如个性化分面图标题、图例、会用到configure_*()方法、selection()方法、condition()方法、
binding_*()方法、
configure_*()方法个性化图像属性
configure_header()方法个性化header
import altair as alt
from vega_datasets import data#vega_datasets为altair的一个内置数据集模块
source = data.cars.url
chart = alt.Chart(source).mark_point().encode(x='Horsepower:Q',
y='Miles_per_Gallon:Q',
color='Origin:N',
column='Origin:N').properties(
width=180, height=180)
chart.configure_header(titleColor='green',
titleFontSize=14,
labelColor='red',
labelFontSize=14)
configure_legend()方法个性化图例
import altair as alt
from vega_datasets import data
source = data.cars.url
chart = alt.Chart(source).mark_point().encode(x='Horsepower:Q',
y='Miles_per_Gallon:Q',
color='Origin:N')
chart.configure_legend(strokeColor='gray',
fillColor='#EEEEEE',
padding=10,
cornerRadius=10,
orient='top-right')
更多configure类方法介绍见:https://altair-viz.github.io/user_guide/configuration.html
selection、condition、binding使得altair图形能和鼠标更好交互
这里主要用到selection()、condition()、binding()方法,简单介绍,详细见:https://altair-viz.github.io/user_guide/interactions.html
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selection()方法
鼠标可以轻捕捉图形某一部分。
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condition()方法
让鼠标捕捉的部分高亮,未捕捉的部分暗淡。
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binding_*()方法
效果如下:
Layer, HConcat, VConcat, Repeat, Facet助力altair轻松构建复合图形
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hconcat水平方向拼图
import altair as alt
from vega_datasets import data
iris = data.iris.url
chart1 = alt.Chart(iris).mark_point().encode(x='petalLength:Q',
y='petalWidth:Q',
color='species:N').properties(
height=300, width=300)
chart2 = alt.Chart(iris).mark_bar().encode(x='count()',
y=alt.Y('petalWidth:Q',
bin=alt.Bin(maxbins=30)),
color='species:N').properties(
height=300, width=100)
chart1 | chart2
alt.hconcat(chart1, chart2)
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vconcat垂直方向拼图
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LayerChart图层叠加
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RepeatChart绘制类似图形
from vega_datasets import data
iris = data.iris.url
base = alt.Chart().mark_point().encode(color='species:N').properties(
width=200, height=200).interactive()
chart = alt.vconcat(data=iris)
for y_encoding in ['petalLength:Q', 'petalWidth:Q']:
row = alt.hconcat()
for x_encoding in ['sepalLength:Q', 'sepalWidth:Q']:
row |= base.encode(x=x_encoding, y=y_encoding)
chart &= row
chart
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FacetChart图形分面
import altair as alt
from altair.expr import datum
from vega_datasets import data
iris = data.iris.url
base = alt.Chart(iris).mark_point().encode(x='petalLength:Q',
y='petalWidth:Q',
color='species:N').properties(
width=160, height=160)
chart = alt.hconcat()
for species in ['setosa', 'versicolor', 'virginica']:
chart |= base.transform_filter(datum.species == species)
chart
Chart.resolve_scale(), Chart.resolve_axis(), and Chart.resolve_legend()个性化复合图形
例如,使用resolve_scale()分别给两个图使用颜色盘。
from vega_datasets import data
source = data.cars()
base = alt.Chart(source).mark_point().encode(
x='Horsepower:Q', y='Miles_per_Gallon:Q').properties(width=200, height=200)
alt.concat(base.encode(color='Origin:N'),
base.encode(color='Cylinders:O')).resolve_scale(color='independent')
3、基于Altair的demo分享
官网关与天气的一个案例
from vega_datasets import data
df = data.seattle_weather()
scale = alt.Scale(
domain=['sun', 'fog', 'drizzle', 'rain', 'snow'],
range=['#e7ba52', '#c7c7c7', '#aec7e8', '#1f77b4', '#9467bd'])
brush = alt.selection(type='interval')
points = alt.Chart().mark_point().encode(
alt.X('temp_max:Q', title='Maximum Daily Temperature (C)'),
alt.Y('temp_range:Q', title='Daily Temperature Range (C)'),
color=alt.condition(brush,
'weather:N',
alt.value('lightgray'),
scale=scale),
size=alt.Size('precipitation:Q',
scale=alt.Scale(range=[1, 200]))).transform_calculate(
"temp_range",
"datum.temp_max - datum.temp_min").properties(
width=600, height=400).add_selection(brush)
bars = alt.Chart().mark_bar().encode(
x='count()',
y='weather:N',
color=alt.Color('weather:N', scale=scale),
).transform_calculate(
"temp_range",
"datum.temp_max - datum.temp_min").transform_filter(brush).properties(
width=600)
alt.vconcat(points, bars, data=df)
其他的案例见官网,不再过多搬运:
官网:https://altair-viz.github.io/index.html
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简单图
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bar图
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line图
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area图
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scatter图
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histgogram图
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map图
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Interactive图
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Case Studies
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Other Charts
标签:altair,python,Chart,mark,Altair,可视化,encode,alt,data 来源: https://blog.csdn.net/qq_21478261/article/details/114850165