Python 个人笔记

最新推荐文章于 2025-09-10 17:59:49 发布

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最新推荐文章于 2025-09-10 17:59:49 发布

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文章标签： python json

原文链接：http://www.cnblogs.com/alex-zen/p/11157392.html

该博客是 Python 学习笔记，涵盖基础数据类型、复合数据类型、运算符、格式化字符串等基础知识，还介绍了函数定义、面向对象编程、模块导入等内容，涉及 os、time、json 等多个内置模块及 requests、pandas 等常用模块。

Python 笔记

hello world

print("hello world!")

print 换行符

print('hello \n world')

print 行结束符

print('hello \n world', end='?')

基础数据类型

a = 6
b = 1.34
c = True
d = 'hello world'

变量命名规范
1. 数字字母下划线
2. 不能以数字开头
3. 不能使用保留字
4. 严格区分大小写
  
  保留字
  from imort as
  True False None
  class pass with
  def yield retrun
  if elif else
  for while continue break
  try raise except assert finally
  is not in and or
  labmda del global nonlocal
复合数据类型

保留字
from	imort	as
True	False	None
class	pass	with
def	yield	retrun
if	elif	else
for	while	continue	break
try	raise	except	assert	finally
is	not	in	and	or
labmda	del	global	nonlocal

list 列表

ls = [6, 1.34, True, 'alex']

tuple 元组

tl = [6, 1.34, True, 'alex']

dict 字典

dl = [6, 1.34, True, 'alex']

set 集合

st = [6, 1.34, True, 'alex']

运算符

格式化字符串

python 3.6 以后支持 f-string format的简化版本

print(f'name is {name}, age is {age}, alex age is {sta.age}')
print(f'get {12*3+5}')
print(F"name is {name:#<6s}, age is {age:3d}, weight is {weight:^9.2f}")
print(F"name is {'davida':#<6s}, age is {111:3d}, weight is {123456.789:9.2f}")
print(f'hex value {254:#X}')

format 方式

print('name is {:6s} next'.format(name))
print('name is {:.3s}'.format(name))
print('age is {:0>6d}'.format(age))
print('age is {:0<6d}'.format(age))
print('age is {:\>6d}'.format(age))
print('age is {:6d}'.format(age + 111))  # 默认是右对齐
# print('age is {:>6d} next'.format(age+1))
print('age is {:<6d} next'.format(age + 1))
print('age is {:^6d} next'.format(age + 1))
print('weight is {:+12.3f}'.format(weight))
print('weight is {:.2%}'.format(weight / 120))
print('id is {:6d}'.format(id))
print('\n\n')

print('name is {}, age is {}'.format(name, age))
print('name is {0}, age is {1}, name is {0}'.format(name, age))
info_list = [name, age]
print('name is {0[0]}, age is {0[1]}, name is {0[0]}'.format(info_list))

print('name is {name}, age is {age}, name is {name}'.format(name=name, age=age))
info_dict = {'name': name, 'age': age}
print('name is {name:?>12s}, age is {age}, name is {name}'.format(**info_dict))

class Student(object):
    def __init__(self, name, age):
        self.name = name
        self.age = age

sta = Student('alex', 12)
stb = Student('lucy', 11)
print('alex name is {0.name}, lucy age is {1.age}'.format(sta, stb))

% 方式: 变量和占位符一一对应,不够灵活

print('age is %d' % age)
print('age is %6d' % age)
print('age is %11d' % age)
print('age is %06d' % age)
print('age is %011d' % age)

print('name is %s' % name)
print('name is %24s' % name)
print('name is %.3s' % name)
print('name is %a' % name)

print('weight is %f' % weight)
print('weight is %.2f' % weight)
# %6.2f 表示总长度为6(包括小数点),保留2位小数
print('weight is %6.2f' % weight)

print('MULTI: name is %s, age is %d' % (name, age))
print('MULTI: name is %s, age is %s' % (name, age))