列表理解中带浮点格式的f字符串 [英] f-string with float formatting in list-comprehension

问题描述

最近在python 3.6中引入了用于字符串格式的[f'str']. 链接.我正在尝试比较.format()和f'{expr}方法.

The [f'str'] for string formatting was recently introduced in python 3.6. link. I'm trying to compare the .format() and f'{expr} methods.

 f ' <text> { <expression> <optional !s, !r, or !a> <optional : format specifier> } <text> ... '

以下是将华氏温度转换为摄氏温度的列表理解.

Below is a list comprehension that converts Fahrenheit to Celsius.

使用.format()方法将结果以浮点数打印到小数点后两位，并添加字符串摄氏:

Using the .format() method it prints the results as float to two decimal points and adds the string Celsius:

Fahrenheit = [32, 60, 102]

F_to_C = ['{:.2f} Celsius'.format((x - 32) * (5/9)) for x in Fahrenheit]

print(F_to_C)

# output ['0.00 Celsius', '15.56 Celsius', '38.89 Celsius']

我正在尝试使用f'{expr}方法复制上面的内容:

I'm trying to replicate the above using the f'{expr} method:

print(f'{[((x - 32) * (5/9)) for x in Fahrenheit]}')  # This prints the float numbers without formatting 

# output: [0.0, 15.555555555555557, 38.88888888888889]
# need instead: ['0.00 Celsius', '15.56 Celsius', '38.89 Celsius']

可以设置f'str'中的浮点格式:

Formatting the float in f'str' can be achieved:

n = 10

print(f'{n:.2f} Celsius') # prints 10.00 Celsius 

尝试将其实现到列表理解中:

Trying to implement that into the list comprehension:

print(f'{[((x - 32) * (5/9)) for x in Fahrenheit]:.2f}') # This will produce a TypeError: unsupported format string passed to list.__format__

是否可以通过使用f'str'的.format()方法获得与上述相同的输出?

Is it possible to achieve the same output as was done above using the .format() method using f'str'?

谢谢.

推荐答案

您需要将f字符串放在理解范围内:

You need to put the f-string inside the comprehension:

[f'{((x - 32) * (5/9)):.2f} Celsius' for x in Fahrenheit]
# ['0.00 Celsius', '15.56 Celsius', '38.89 Celsius']

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