python快速入门1

记录python若干功能特点，帮助快速了解python语法

#!/usr/bin/env python

# 验证若干python功能

import pandas as pd
import numpy as np
import time
import datetime

from string import Template

if __name__ == "__main__":
    # 格式化字符串，带参数名称
    tmpl = Template("Hello, $who! $what enough for ya?")
    str2 = tmpl.substitute(who="Mars", what="Dusty")
    print(str2)

    # 格式化一个字符串...直接使用外部变量
    day = 20230308
    str3 = f""" today is {day} . """
    print("str3:", str3)

    # 格式化一个字符串，通过传入对应位置参数赋值
    str4 = " paraA:{} , paraB:{} , paraC:{}, paraD:{}"
    str5 = str4.format("A", "B", "C", day)
    print("str4:", str4)
    print("str5:", str5)

    # 用get方法访问字典，可以避免程序出现错误或异常
    dic1: dict = {'name': 'henry', 'age': "123"}
    print("dic1.get name:", dic1.get('name', "name_bk"))
    print("dic1.get name2:", dic1.get('name2', "name_bk"))

    # 用作布尔表达式（如用作if语句中的条件）时，下面的值都将被解释器视为假：
    # False  None  0  ""  ()  []   {}
    if None:
        print("true")
    else:
        print(None)

    # 程序里面的断言
    age = -1
    assert (0 < age < 100, "The age must be realistic")
    print("age:", age)