【python实战】matplotlib绘图（三）

今天主要讲一下get到的一些小技能，包括：

当坐标轴标签太长，出框的时候，自动调整子图——语句：plt.tight_layout()
自动调整text（文本标签）的位置，避免重叠——调包：adjustText（具体文档见adjustText文档）
调用已有的颜色主题；Choosing Colormaps in Matplotlib

import matplotlib.pyplot as plt
import matplotlib
import numpy as np
import matplotlib.transforms as mtransforms
from matplotlib.ticker import FuncFormatter
from adjustText import adjust_text
from matplotlib import cm
#设置字体、图形样式
matplotlib.rcParams['font.sans-serif'] = ['SimHei']
matplotlib.rcParams['font.family']='sans-serif'
matplotlib.rcParams['axes.unicode_minus'] = False
# 颜色转换
def RGB_to_Hex(tmp):
    rgb = tmp.split(',')#将RGB格式划分开来
    strs = '#'
    for i in rgb:
        num = int(i)#将str转int
        #将R、G、B分别转化为16进制拼接转换并大写
        strs += str(hex(num))[-2:].replace('x','0').upper()
    return strs

1.左右条形图（left_right_barh)

left_right_barh.png

def left_right_barh(fig,subplotid,ylabel,values1,values2,label1,label2,textformat,withlegend=1,category=0,filename=0):
    values1=[0-i for i in values1]
    # 倒序
    ylabel,values1,values2=ylabel[::-1],values1[::-1],values2[::-1]
    # 作图
    ax=fig.add_subplot(subplotid)
    barh1=ax.barh(ylabel,width=values1,label=label1)
    barh2=ax.barh(ylabel,width=values2,label=label2)
    # 去掉边框
    orientation=['top','bottom','right']
    for o in orientation:
        ax.spines[o].set_visible(False)
    # 去掉xticks
    ax.set_xticks(())
    # 图例
    if withlegend:
        ax.legend(ncol=2, bbox_to_anchor=(0.5, -0.1),edgecolor='w',
                      loc='lower center', fontsize='small')
    # y轴标题
    if category:
        ax.set_ylabel(category)
    # 添加barh的数据标签
    texts=[]
    for b in barh1:
        texts.append(ax.text(b.get_width()-0.04,b.get_y()+b.get_height()/3,
            format(-b.get_width(),textformat),va="center",ha='left'))
    for b in barh2:
        texts.append(ax.text(b.get_width(),b.get_y()+b.get_height()/3,
            format(b.get_width(),textformat),va="center",ha='right'))
    adjust_text(texts,only_move={'points':'x', 'text':'x', 'objects':'x'}) #避免y轴上的调整
    plt.tight_layout()#调整子图，避免标签出框，自动调整的语句,图则会自动调整标签大小
    if filename:
        plt.savefig(filename,dpi=600)
    return ax
def left_right_barh_ex():
    # 数据
    ylabel=["不识字或识字很少","小学","初中","普通高中","中等职业/技术/师范学校","高职/大专","本科","研究生","博士"]
    values1=[0.0477,0.2013,0.2751,0.128,0.0774,0.1219,0.1244,0.0172,0.007]
    values2=[0.0196,0.1405,0.2834,0.1577,0.0597,0.1275,0.1698,0.0299,0.0119]
    textformat='.2%'
    fig=plt.figure()
    left_right_barh(fig,111,ylabel=ylabel,values1=values1,values2=values2,
        label1='母亲',label2='父亲',filename="left_right_barh.png",textformat=textformat)
    plt.show()
left_right_barh_ex()

若不加plt.tight_layout()的效果如下，可以看到，纵坐标标签太长已经出去了。

left_right_barh（轴标签未调整）.png

若不加adjust_text(texts,only_move={'points':'x', 'text':'x', 'objects':'x'})的效果如下，可以看到，数据标签挤在一起了。

left_right_barh（数据标签未调整）.png

adjustText这个包在做散点图进行数据标签添加时，应该是最有用的，文档中的例子如下：

adjustText.png

2.简单柱状图（simple_bar)

simple_bar1.png

def simple_bar(xlabel,value,colorname,filename):
    # 系列颜色选取
    colorname=cm.get_cmap(name=colorname)
    color=colorname(value)
    fig=plt.figure()
    ax=fig.add_subplot()
    bar=ax.bar(xlabel,value,color=color)
    # 去掉边框
    orientation=['top','left','right']
    for o in orientation:
        ax.spines[o].set_visible(False)
    # 去掉xticks
    ax.set_yticks(())
    # 文本标签
    for b in bar:
        ax.text(b.get_x()+b.get_width()/2,b.get_height()+0.01,
            format(b.get_height(),'.2%'),va="center",ha='center')
    plt.savefig(filename,dpi=600)
    plt.show()
def simple_bar_ex1():
    xlabel=["5万元以下",    "5万-10万",   "11万-20万",  "21万-40万",  "41万以上"]
    value=[0.3417,  0.3095, 0.2272, 0.0858, 0.0359]
    simple_bar(xlabel,value,colorname='coolwarm',filename='simple_bar1.png')

这里用的colorname是”coolwarm”，改一下这个colorname为“Pastel1”，效果如下：

simple_bar11.png

现有的主题颜色有：

color1.png

color2.png

color3.png

color4.png

color5.png

color6.png

color7.png