基于matplotlib输出心电图纸到pdf文件

ecg_chart.py

#*-- coding: utf-8 --*

import matplotlib

X_INCH = 7
Y_INCH = 11
X_MM = int(X_INCH*25.4)
Y_MM = int(Y_INCH*25.4)

while X_MM % 5 != 1:
    X_MM -= 1

while Y_MM % 5 != 1:
    Y_MM -= 1

M_X_INCH = float(X_MM) / 25.4
M_Y_INCH = float(Y_MM) / 25.4
THIN_WIDTH = 0.2
FAT_WIDTH = 0.6


matplotlib.use('pdf')
from matplotlib.backends.backend_pdf import PdfPages

import matplotlib.pyplot as plt

with PdfPages('ecg.pdf') as pdf:

    f = plt.figure(figsize=(M_X_INCH,M_Y_INCH), dpi=600)  # 英寸
    plt.rc('lines', linewidth=THIN_WIDTH, color='hotpink')
    # 坐标系
    # axes = f.add_subplot(1,1,1)
    axes = f.add_axes( (0, 0, 1, 1), frame_on=False )
    axes.set_xlim(-0.5, X_MM-0.5)     # 毫米
    axes.set_ylim(-0.5, Y_MM-0.5)    
    def get_line_width(i):
        if i % 5 == 0 :
            return FAT_WIDTH 
        else:
            return THIN_WIDTH
    for i in range(0, X_MM):
        axes.axvline(x=i,linewidth=get_line_width(i))
    for i in range(0, Y_MM):
        axes.axhline(y=i,linewidth=get_line_width(i))

    pdf.savefig()
    plt.close()

windows 上有报错的，注释这行解决了我的错误
#matplotlib.use('pdf')