如何将多个直方图保存到多个pdf文件中

import matplotlib.pyplot as plt
from matplotlib.backends.backend_pdf import PdfPages

data1 = [1, 2, 3, 4, 5]
data2 = [2, 4, 6, 8, 10]
data3 = [3, 6, 9, 12, 15]

pdf = PdfPages('histograms.pdf')

# 绘制直方图1
plt.hist(data1)
plt.title('Histogram 1')
plt.xlabel('X-axis')
plt.ylabel('Y-axis')
pdf.savefig()
plt.close()

# 绘制直方图2
plt.hist(data2)
plt.title('Histogram 2')
plt.xlabel('X-axis')
plt.ylabel('Y-axis')
pdf.savefig()
plt.close()

# 绘制直方图3
plt.hist(data3)
plt.title('Histogram 3')
plt.xlabel('X-axis')
plt.ylabel('Y-axis')
pdf.savefig()
plt.close()

pdf.close()