位置格式化
Python 中的正则表达式
Maria Eugenia Inzaugarat
Data scientist
什么是字符串格式化？
字符串插值
在预定义文本中插入自定义字符串或变量：
custom_string = "String formatting"
print(f"{custom_string} is a powerful technique")
String formatting is a powerful technique
- 用途：
- 图表标题
- 显示消息或错误
- 向函数传递语句
格式化方法
- 位置格式化
- 格式化字符串字面值
- 模板方法
位置格式化
- 用值替换占位符
str.format()
print("Machine learning provides {} the ability to learn {}".format("systems", "automatically"))
Machine learning provides systems the ability to learn automatically
位置格式化
- 对初始字符串和传入方法的值都使用变量
my_string = "{} rely on {} datasets"
method = "Supervised algorithms"
condition = "labeled"
print(my_string.format(method, condition))
Supervised algorithms rely on labeled datasets
重排值
- 在占位符中加入索引号以重新排序值
print("{} has a friend called {} and a sister called {}".format("Betty", "Linda", "Daisy"))
Betty has a friend called Linda and a sister called Daisy
print("{2} has a friend called {0} and a sister called {1}".format("Betty", "Linda", "Daisy"))
Daisy has a friend called Betty and a sister called Linda
命名占位符
- 为占位符指定名称
tool="Unsupervised algorithms"
goal="patterns"
print("{title} try to find {aim} in the dataset".format(title=tool, aim=goal))
Unsupervised algorithms try to find patterns in the dataset
命名占位符
my_methods = {"tool": "Unsupervised algorithms", "goal": "patterns"}
print('{data[tool]} try to find {data[goal]} in the dataset'.format(data=my_methods))
Unsupervised algorithms try to find patterns in the dataset
格式说明符
- 指定数据类型：
{index:specifier}
print("Only {0:f}% of the {1} produced worldwide is {2}!".format(0.5155675, "data", "analyzed"))
Only 0.515568% of the data produced worldwide is analyzed!
print("Only {0:.2f}% of the {1} produced worldwide is {2}!".format(0.5155675, "data", "analyzed"))
Only 0.52% of the data produced worldwide is analyzed!
格式化日期时间
from datetime import datetime
print(datetime.now())
datetime.datetime(2019, 4, 11, 20, 19, 22, 58582)
print("Today's date is {:%Y-%m-%d %H:%M}".format(datetime.now()))
Today's date is 2019-04-11 20:20
Vamos praticar!
Python 中的正则表达式
