python3:打印和.format()的{}内的可变长度值

Question

是否有方法在python中创建具有灵活{}调整的格式化字符串？

默认的方法是：

In [1]: "{:20}Hey B! You are {} blocks away.".format("Hey A!", 20-6)
Out[1]: 'Hey A!              Hey B! You are 14 blocks away.'

但是，有没有一种方法来编码“A和B之间的距离”灵活？像这样..？

#not working
In [2]: x = 20
In [3]: "{:x}Hey! You are {} blocks away.".format("Hey! A", x-6)
Out[3]: 'Hey A!              Hey B! You are 14 blocks away.'

In [2]: x = 30
In [3]: "{:x}Hey! You are {} blocks away.".format("Hey! A", x-6)
Out[3]: 'Hey A!                        Hey B! You are 14 blocks away.'

或者还有其他简单方便的方法来完成它呢？

Answer 1

Python允许嵌套格式运算符。当按位置操作时，每个位置参数都由其开口大括号出现的位置来计算。因此，要按照需要使用x来为"Hey! A"辩护，您可以这样做：

"{:{}}Hey! You are {} blocks away.".format("Hey! A", x, x-6)
   ^^ These brackets fill in the desired width using the second positional arg

如果您想避免在本例中考虑编号，可以将提供宽度的参数命名为通过关键字传递的参数，例如width

"{:{width}}Hey! You are {} blocks away.".format("Hey! A", x-6, width=x)

您可以在“嵌套参数和更复杂的示例”在这里下面看到更多的示例。

Answer 2

这不是很漂亮，但这是一种方式：

x = 20

("{:"+str(x)+"}Hey! You are {} blocks away.").format("Hey! A", x-6)

# 'Hey! A              Hey! You are 14 blocks away.'

替代语法：

''.join(("{:", str(x), "}Hey! You are {} blocks away.")).format("Hey! A", x-6)