机器学习——python之matplotlib的使用——①
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2022-03-18 20:40:54
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1.安装matplotlib 库
pip install matplotlib -i https://pypi.tuna.tsinghua.edu.cn/simple//2.折线图
2.1折线图的绘制
from matplotlib import pyplot as plt
# x轴的位置
x = range(1, 8)
# y轴的位置
y = [17, 17, 18, 15, 11, 11, 13]
# 传入x和y, 通过plot画折线图
plt.plot(x, y)
# 显示
plt.show()2.2折线的颜色形状设置
- 设置颜色color='red'
- 设置透明度alpha=【0-1】
- 设置线的样式linestyle='--'
- 设置线的宽度linewidth=3
from matplotlib import pyplot as plt
# 绘制折线(x,y)
# [1, 0, 9], [4, 5, 6]=====> (1,4), (0,5), (9,6)
"""
**Colors**
The supported color abbreviations are the single letter codes
============= ===============================
character color
============= ===============================
``'b'`` blue
``'g'`` green
``'r'`` red
``'c'`` cyan
``'m'`` magenta
``'y'`` yellow
``'k'`` black
``'w'`` white
============= ===============================
**Line Styles**
============= ===============================
character description
============= ===============================
``'-'`` solid line style
``'--'`` dashed line style
``'-.'`` dash-dot line style
``':'`` dotted line style
============= ===============================
Example format strings::
'b' # blue markers with default shape
'or' # red circles
'-g' # green solid line
'--' # dashed line with default color
'^k:' # black triangle_up markers connected by a dotted line
"""
plt.plot([1, 0, 9], [4, 5, 6], color='red', alpha=0.8, linestyle='--', linewidth=5)
# 显示
plt.show()2.3折点样式
- 设置折点marker='o'
- 设置折点大小markersize=12
- 设置折点边框颜色markeredgecolor='green'
- 设置折点边框大小markeredgewidth=5
# 导入库
from matplotlib import pyplot as plt
# 绘制折线(x,y)
# [1, 0, 9], [4, 5, 6]=====> (1,4), (0,5), (9,6)
"""
**Colors**
The supported color abbreviations are the single letter codes
============= ===============================
character color
============= ===============================
``'b'`` blue
``'g'`` green
``'r'`` red
``'c'`` cyan
``'m'`` magenta
``'y'`` yellow
``'k'`` black
``'w'`` white
============= ===============================
**Markers**
============= ===============================
character description
============= ===============================
``'.'`` point marker
``','`` pixel marker
``'o'`` circle marker
``'v'`` triangle_down marker
``'^'`` triangle_up marker
``'<'`` triangle_left marker
``'>'`` triangle_right marker
``'1'`` tri_down marker
``'2'`` tri_up marker
``'3'`` tri_left marker
``'4'`` tri_right marker
``'s'`` square marker
``'p'`` pentagon marker
``'*'`` star marker
``'h'`` hexagon1 marker
``'H'`` hexagon2 marker
``'+'`` plus marker
``'x'`` x marker
``'D'`` diamond marker
``'d'`` thin_diamond marker
``'|'`` vline marker
``'_'`` hline marker
============= ===============================
**Line Styles**
============= ===============================
character description
============= ===============================
``'-'`` solid line style
``'--'`` dashed line style
``'-.'`` dash-dot line style
``':'`` dotted line style
============= ===============================
Example format strings::
'b' # blue markers with default shape
'or' # red circles
'-g' # green solid line
'--' # dashed line with default color
'^k:' # black triangle_up markers connected by a dotted line
"""
plt.plot([1, 0, 9], [4, 5, 6], color='red', alpha=0.8, linestyle='--', linewidth=5, marker='o', markersize=12)
# 显示
plt.show()
2.4 设置图片的大小和保存
- 设置图片的大小plt.figure(figsize=(20, 8))
- 设置图片的分辨率 plt.figure(figsize=(20, 8), dpi=80)
- 保存图片plt.savefig("./1.svg")
- 注：在保存之前不要调用show()方法，顺序应该是savefig()——>show()
# encoding: utf-8
# time : 2020-09-15 17:29
# author : 进击的灰太狼
# 导入库
from matplotlib import pyplot as plt
# 设置图片大小figsize, 分辨率：dpi
plt.figure(figsize=(20, 8), dpi=80)
# 绘制折线(x,y)
# [1, 0, 9], [4, 5, 6]=====> (1,4), (0,5), (9,6)
"""
**Colors**
The supported color abbreviations are the single letter codes
============= ===============================
character color
============= ===============================
``'b'`` blue
``'g'`` green
``'r'`` red
``'c'`` cyan
``'m'`` magenta
``'y'`` yellow
``'k'`` black
``'w'`` white
============= ===============================
**Markers**
============= ===============================
character description
============= ===============================
``'.'`` point marker
``','`` pixel marker
``'o'`` circle marker
``'v'`` triangle_down marker
``'^'`` triangle_up marker
``'<'`` triangle_left marker
``'>'`` triangle_right marker
``'1'`` tri_down marker
``'2'`` tri_up marker
``'3'`` tri_left marker
``'4'`` tri_right marker
``'s'`` square marker
``'p'`` pentagon marker
``'*'`` star marker
``'h'`` hexagon1 marker
``'H'`` hexagon2 marker
``'+'`` plus marker
``'x'`` x marker
``'D'`` diamond marker
``'d'`` thin_diamond marker
``'|'`` vline marker
``'_'`` hline marker
============= ===============================
**Line Styles**
============= ===============================
character description
============= ===============================
``'-'`` solid line style
``'--'`` dashed line style
``'-.'`` dash-dot line style
``':'`` dotted line style
============= ===============================
Example format strings::
'b' # blue markers with default shape
'or' # red circles
'-g' # green solid line
'--' # dashed line with default color
'^k:' # black triangle_up markers connected by a dotted line
"""
plt.plot([1, 0, 9], [4, 5, 6], color='red', alpha=0.8, linestyle='--', linewidth=5, marker='o', markersize=12)
# 保存图片
plt.savefig("./1.svg", bbox_inches='tight')
# 显示
plt.show()
2.5 绘制X轴和Y轴的刻度
- plt.xticks(ticks=None, labels=None)
- plt.yticks(ticks=None, labels=None)
- ticks：确定有多少个刻度
- labels：每个刻度的具体显示值
# encoding: utf-8
# time : 2020-09-15 17:29
# author : 进击的灰太狼
# 导入库
import random
from matplotlib import pyplot as plt
# 设置图片大小figsize, 分辨率：dpi
# plt.figure(figsize=(20, 8), dpi=80)
# 绘制折线(x,y)
# [1, 0, 9], [4, 5, 6]=====> (1,4), (0,5), (9,6)
"""
**Colors**
The supported color abbreviations are the single letter codes
============= ===============================
character color
============= ===============================
``'b'`` blue
``'g'`` green
``'r'`` red
``'c'`` cyan
``'m'`` magenta
``'y'`` yellow
``'k'`` black
``'w'`` white
============= ===============================
**Markers**
============= ===============================
character description
============= ===============================
``'.'`` point marker
``','`` pixel marker
``'o'`` circle marker
``'v'`` triangle_down marker
``'^'`` triangle_up marker
``'<'`` triangle_left marker
``'>'`` triangle_right marker
``'1'`` tri_down marker
``'2'`` tri_up marker
``'3'`` tri_left marker
``'4'`` tri_right marker
``'s'`` square marker
``'p'`` pentagon marker
``'*'`` star marker
``'h'`` hexagon1 marker
``'H'`` hexagon2 marker
``'+'`` plus marker
``'x'`` x marker
``'D'`` diamond marker
``'d'`` thin_diamond marker
``'|'`` vline marker
``'_'`` hline marker
============= ===============================
**Line Styles**
============= ===============================
character description
============= ===============================
``'-'`` solid line style
``'--'`` dashed line style
``'-.'`` dash-dot line style
``':'`` dotted line style
============= ===============================
Example format strings::
'b' # blue markers with default shape
'or' # red circles
'-g' # green solid line
'--' # dashed line with default color
'^k:' # black triangle_up markers connected by a dotted line
"""
# plt.plot([1, 0, 9], [4, 5, 6], color='red', alpha=0.8, linestyle='--', linewidth=5, marker='o', markersize=12)
# x轴的位置
x = range(2, 26, 2)
# y轴的位置
y = [random.randint(15, 30) for i in x]
x_ticks_label = ["{}:00".format(i) for i in x]
# plt.xticks(range(1, 30))
# 第一个参数：确定有多少个刻度，第二个参数：每个刻度的具体显示值，rotation = 45 让字旋转45度
plt.xticks(x, x_ticks_label, rotation=45)
# 设置y轴的刻度标签
y_ticks_label = ["{}℃".format(i) for i in range(min(y), max(y)+1)]
plt.yticks(range(min(y), max(y)+1), y_ticks_label)
plt.plot(x, y, color='red', alpha=0.8, linestyle='--', linewidth=5, marker='o', markersize=12)
# 保存图片
# bbox_inches='tight' 不会忽略不可见的轴
# plt.savefig("./1.svg", bbox_inches='tight')
# 显示
plt.show()
2.6 设置显示中文
windows查看字体：C:\Windows\Fonts
- 方法①
# 用来正常显示中文标签 plt.rcParams['font.sans-serif'] = ['SimHei'] # 用来正常显示负号 plt.rcParams['axes.unicode_minus'] = False
# 设置图片标题
plt.title("折线图")
plt.ylabel("温度")
plt.xlabel("时间")- 方法②
from matplotlib import font_manager my_font = font_manager.FontProperties(fname="C:\\Windows\\Fonts\\simsun.ttc",)
# 设置图片标题
plt.title("折线图", fontproperties=my_font, size=18)
plt.ylabel("温度", fontproperties=my_font, size=12)
plt.xlabel("时间", fontproperties=my_font, size=12)2.7 一图多线
# encoding: utf-8
# time : 2020-09-15 17:29
# author : 进击的灰太狼
# 导入库
import random
from matplotlib import pyplot as plt
from matplotlib import font_manager
my_font = font_manager.FontProperties(fname="C:\\Windows\\Fonts\\simsun.ttc", size=24)
# 用来正常显示中文标签
plt.rcParams['font.sans-serif'] = ['SimHei']
# 用来正常显示负号
plt.rcParams['axes.unicode_minus'] = False
# 假设大家在30岁的时候，根据自己的实际情况，统计出来你和你同事各自从11岁到30岁每年交的男/女朋友的数量如列表y1和y2，请在一个图中绘制出该数据的折线图，从而分析每年交朋友的数量走势。
y1 = [1, 0, 1, 1, 2, 4, 3, 4, 4, 5, 6, 5, 4, 3, 3, 1, 1, 1, 1, 1]
y2 = [1, 0, 3, 1, 2, 2, 3, 4, 3, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1]
x = range(11, 31)
# 设置图形
plt.figure(figsize=(20, 8), dpi=80)
plt.plot(x, y1, color='red', label='自己')
plt.plot(x, y2, color='blue', label='朋友')
# 设置x轴刻度
x_tick_labels = ['{}岁'.format(i) for i in x]
plt.xticks(x, x_tick_labels, rotation=45, fontproperties=my_font, size=18)
plt.yticks(fontproperties=my_font, size=18)
# 绘制网格（网格也是可以设置线的样式)
# alpha=0.4 设置透明度
plt.grid(alpha=0.4)
# 添加图例(注意：只有在这里需要添加prop参数是显示中文，其他的都用fontproperties)
# 设置位置loc : upper left、 lower left、 center left、 upper center
plt.legend(loc='upper right', prop=my_font)
# 展示
plt.show()2.8 一图多个坐标系子图
# encoding: utf-8
# time : 2020-09-15 17:29
# author : 进击的灰太狼
# 导入库
# add_subplot方法----给figure新增子图
import numpy as np
import matplotlib.pyplot as plt
x = np.arange(1, 100)
# 新建figure对象
fig = plt.figure(figsize=(20, 10), dpi=80)
# 新建子图1
ax1 = fig.add_subplot(2, 2, 1)
ax1.plot(x, x)
# 新建子图2
ax2 = fig.add_subplot(2, 2, 2)
ax2.plot(x, x ** 2)
ax2.grid(color='r', linestyle='--', linewidth=1, alpha=0.3)
# 新建子图3
ax3 = fig.add_subplot(2, 2, 3)
ax3.plot(x, np.log(x))
plt.show()2.9 设置坐标轴范围
import matplotlib.pyplot as plt
import numpy as np
x = np.arange(-10, 11, 1)
y = x**2
plt.plot(x, y)
# 可以调x轴的左右两边
# 只调一边
# 调节x轴
plt.xlim(xmin=-10)
plt.xlim(xmax=10)
# 调节y轴
plt.ylim(ymin=0)
plt.ylim(ymax=100)
plt.show()
2.10 改变坐标轴的默认显示方式
import matplotlib.pyplot as plt
y = range(0, 14, 2)
# x轴的位置
x = [-3, -2, -1, 0, 1, 2, 3]
# plt.figure(figsize=(20, 8), dpi=80)
# 获得当前图表的图像
ax = plt.gca()
# 设置图型的包围线
ax.spines['right'].set_color('none')
ax.spines['top'].set_color('none')
ax.spines['bottom'].set_color('blue')
ax.spines['left'].set_color('red')
# 设置底边的移动范围，移动到y轴的0位置,'data':移动轴的位置到交叉轴的指定坐标
ax.spines['bottom'].set_position(('data', 0))
ax.spines['left'].set_position(('data', 0))
plt.plot(x, y)
plt.show()