格式化字符串字面量

Python 中的正则表达式

Maria Eugenia Inzaugarat

Data Scientist

f-strings

  • 语法最简
  • 给字符串加前缀 f

way = "code"
method = "learning Python faster"
print(f"Practicing how to {way} is the best method for {method}")

Practicing how to code is the best method for learning Python faster
Python 中的正则表达式

类型转换

  • 可用的转换：
    • !s（字符串形式）
    • !r（可打印表示，即带引号的字符串）
    • !a（同 !r，但转义非 ASCII 字符）

 

name = "Python"

print(f"Python is called {name!r} due to a comedy series")

Python is called 'Python' due to a comedy series
Python 中的正则表达式

格式说明符

  • 标准格式说明符：
    • e（科学计数法，如 5×10^3）
    • d（整数，如 4）
    • f（浮点数，如 4.5353）

 

number = 90.41890417471841

print(f"In the last 2 years, {number:.2f}% of the data was produced worldwide!")

In the last 2 years, 90.42% of the data was produced worldwide!
Python 中的正则表达式

格式说明符

 

  • datetime

 

from datetime import datetime
my_today = datetime.now()

print(f"Today's date is {my_today:%B %d, %Y}")

Today's date is April 14, 2019
Python 中的正则表达式

索引取值

family = {"dad": "John", "siblings": "Peter"}

print("Is your dad called {family[dad]}?".format(family=family))

Is your dad called John?

 

  • 索引取值需加引号：family["dad"]
print(f"Is your dad called {family[dad]}?")

NameError: name 'dad' is not defined
Python 中的正则表达式

转义序列

  • 转义序列：反斜杠 \
print("My dad is called "John"")

SyntaxError: invalid syntax

 

my_string = "My dad is called \"John\""

My dad is called "John"
Python 中的正则表达式

转义序列

family = {"dad": "John", "siblings": "Peter"}
  • f-string 中不允许反斜杠
print(f"Is your dad called {family[\"dad\"]}?")

SyntaxError: f-string expression part cannot include a backslash

 

print(f"Is your dad called {family['dad']}?")

Is your dad called John?
Python 中的正则表达式

内联操作

  • 优点：可内联求值与调用函数
my_number = 4
my_multiplier = 7

print(f'{my_number} multiplied by {my_multiplier} is {my_number * my_multiplier}')

4 multiplied by 7 is 28
Python 中的正则表达式

调用函数

def my_function(a, b):
  return a + b

print(f"If you sum up 10 and 20 the result is {my_function(10, 20)}")

If you sum up 10 and 20 the result is 30
Python 中的正则表达式

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Python 中的正则表达式

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