如何在 Python 中格式化由宽度而不是精度分隔的浮点数？

Question

I am looking for a way to format a number string in Python in such a way that I have a fixed width, regardless the precision. I'll give an example below:

Suppose I want to format the float for a fixed width = 8 and precision = 4. If I use the following code:

number = 3.141516
'{:8.4f}'.format(numero)

it works well for small numbers. But if I want to format a number like 1000000, the output is 1000000.0000 , thus giving a width greater than 8.

Is there a way I could set the formatter in a such a way I can get a fixed width in this case?

Thanks in advance

Answer 1

I'm not totaly sure of what you are asking. should the width of 8 include the dot?

see if this answer your question:

print(f'{str(float(number)) + "0"*8}'[:8])

but note that in a 7 digit integer a dot will be left by the end so you need to catch this exception. I guess by adding a 0 on front of the number and replacing the dot so it maintains the 8 width, but it depend on what you are searching.

Answer 2

The width of the number also depends on the precision. As you want a fixed width, I would suggest you to use f strings and set the precision to be equal to the width in case the precision value is more than the width.

Syntax for f strings : f'{value:{width}.{precision}}'

• The precision includes integer + decimal value

This is how you could use it:

    n = 3.141516
    print(f'{n:{8}.{4}}')

The output that you will get is:

 3.142