Python学习笔记第21天

谏言：穷则独善其身，达则兼济天下

模块datetime

from datetime import datetime
first_date = datetime.strptime('2014-7-1','%Y-%m-%d')
print(first_date)

2014-07-01 00:00:00

在图标中添加日期

import csv
from datetime import datetime
import matplotlib.pyplot as plt
​
filename='sitka_weather_07-2014.csv'
with open(filename) as f:
    reader = csv.reader(f)
    header_row = next(reader)
    dates,highs=[],[]
    for row in reader:
        current_date = datetime.strptime(row[0],'%Y-%m-%d')
        dates.append(current_date)
        high=int(row[1])
        highs.append(high)
​
fig =plt.figure(dpi=128,figsize=(10,6))
plt.plot(dates,highs,c='red')
# 设置图形风格
plt.title("Daily high temperatures , July 2014", fontsize=24)
plt.xlabel('', fontsize=16)
fig.autofmt_xdate()
plt.ylabel("Temperature (F)", fontsize=16)
plt.tick_params(axis='both', which='major', labelsize=16)
​
plt.show()

涵盖更长的时间

import csv
from datetime import datetime
import matplotlib.pyplot as plt
​
filename='sitka_weather_2014.csv'
with open(filename) as f:
    reader = csv.reader(f)
    header_row = next(reader)
    dates,highs=[],[]
    for row in reader:
        current_date = datetime.strptime(row[0],'%Y-%m-%d')
        dates.append(current_date)
        high=int(row[1])
        highs.append(high)
​
fig =plt.figure(dpi=128,figsize=(10,6))
plt.plot(dates,highs,c='red')
# 设置图形风格
plt.title("Daily high temperatures -2014", fontsize=24)
plt.xlabel('', fontsize=16)
fig.autofmt_xdate()
plt.ylabel("Temperature (F)", fontsize=16)
plt.tick_params(axis='both', which='major', labelsize=16)
​
plt.show()

 

再绘制一个数据系列

import csv
from datetime import datetime
import matplotlib.pyplot as plt
​
filename='sitka_weather_2014.csv'
with open(filename) as f:
    reader = csv.reader(f)
    header_row = next(reader)
    dates,highs,lows=[],[],[]
    for row in reader:
        current_date = datetime.strptime(row[0],'%Y-%m-%d')
        dates.append(current_date)
        
        high=int(row[1])
        highs.append(high)
        
        low = int(row[3])
        lows.append(low)
​
fig =plt.figure(dpi=128,figsize=(10,6))
plt.plot(dates,highs,c='red')
plt.plot(dates,lows,c='skyblue')
# 设置图形风格
plt.title("Daily high and low temperatures -2014", fontsize=24)
plt.xlabel('', fontsize=16)
fig.autofmt_xdate()
plt.ylabel("Temperature (F)", fontsize=16)
plt.tick_params(axis='both', which='major', labelsize=16)
​
plt.show()

import csv
from datetime import datetime
import matplotlib.pyplot as plt
​
filename='sitka_weather_2014.csv'
with open(filename) as f:
    reader = csv.reader(f)
    header_row = next(reader)
    dates,highs,lows=[],[],[]
    for row in reader:
        current_date = datetime.strptime(row[0],'%Y-%m-%d')
        dates.append(current_date)
        high=int(row[1])
        highs.append(high)
        low = int(row[3])
        lows.append(low)
​
fig =plt.figure(dpi=128,figsize=(10,6))
plt.plot(dates,highs,c='red',alpha=0.5)
plt.plot(dates,lows,c='red',alpha=0.5)
plt.fill_between(dates,highs,lows,facecolor='blue',alpha=0.1)
​
​
​
plt.plot(dates,highs,c='red')
plt.plot(dates,lows,c='skyblue')
# 设置图形风格
plt.title("Daily high and low temperatures -2014", fontsize=24)
plt.xlabel('', fontsize=16)
fig.autofmt_xdate()
plt.ylabel("Temperature (F)", fontsize=16)
plt.tick_params(axis='both', which='major', labelsize=16)
​
plt.show()

给图表区域着色

错误检查

import csv
from datetime import datetime
import matplotlib.pyplot as plt
​
filename='death_valley_2014.csv'
with open(filename) as f:
    reader = csv.reader(f)
    header_row = next(reader)
    dates,highs,lows=[],[],[]
    for row in reader:
        try:
            current_date = datetime.strptime(row[0],'%Y-%m-%d')
            high=int(row[1])
            low = int(row[3])
        except ValueError:
            print(current_date,'数据缺失')
        else:
            dates.append(current_date)
            highs.append(high)
            lows.append(low)
​
fig =plt.figure(dpi=128,figsize=(10,6))
plt.plot(dates,highs,c='red',alpha=0.5)
plt.plot(dates,lows,c='red',alpha=0.5)
plt.fill_between(dates,highs,lows,facecolor='blue',alpha=0.1)
​
​
​
plt.plot(dates,highs,c='red')
plt.plot(dates,lows,c='skyblue')
# 设置图形风格
title="Daily high and low temperatures -2014\nDeath Valley,CA" 
plt.title(title,fontsize=20)
plt.xlabel('', fontsize=16)
fig.autofmt_xdate()
plt.ylabel("Temperature (F)", fontsize=16)
plt.tick_params(axis='both', which='major', labelsize=16)
​
plt.show()
​
# 报错
# ValueError                                Traceback (most recent call last)
# <ipython-input-14-ccfb79eb7adc> in <module>
#      12         dates.append(current_date)
#      13 
# ---> 14         high=int(row[1])
#      15         highs.append(high)
#      16 
​
# ValueError: invalid literal for int() with base 10: ''
# 数据为空字符串
# 需要进行处理

2014-02-16 00:00:00 数据缺失