# coding = utf-8

import pandas as pd

from matplotlib import pyplot as plt

file_path = "files/books.csv"

df = pd.read_csv(file_path)

# print(df.head(2))
#
# print(df.info())

# data1 = df[pd.notnull(df["original_publication_year"])]
#
# grouped = data1.groupby(by="original_publication_year").count()["title"]

# print(grouped)
# print(type(grouped))


# 不同年份数的平均价格

# 去除original_publication_year列中nan的行
data1 = df[pd.notnull(df["original_publication_year"])]

grouped = data1["average_rating"].groupby(by=data1["original_publication_year"]).mean()

# print(grouped)

_x = grouped.index
_y = grouped.values

# 画图
plt.figure(figsize=(20, 8), dpi=80)
plt.plot(range(len(_x)), _y)
plt.xticks(list(range(len(_x)))[::10], _x[::10].astype(int), rotation=45)
plt.show()
