Python 2.7，Sypder，保留小数点前的有效数字

Question

I am trying to figure out how to keep all significant figures in a value. So for example let's say I want values 'a' and 'b':

    a = 00
    b = 00

I want to be able keep both 0's but if it just reverts to '0'. I have tried adding a decimal, '.', after '00' but this just gives '0.0'. For reference I am using this to create a file name for my code to read:

         filename = 'Folder/File' + str(a) + '-' str(b) + '.file'

where the 'b' would be restated once a loop is completed:

    b += 10

with the hope that this sets a to be '01' and so on. I then state that if b reaches a certain number then the 'a' value is restated and 'b' reset to '00':

    if b > 50:
        a += 1
        b = 00

As might be obvious this is my attempt to basically set up a 'time'-like function. This is because the part of the filenames that change are the time they were made. This is maddening because I am working with 2670+ files and I need a good way to set them up for reading.

Answer 1

您可以在计算filename时使用字符串格式来创建填充，而不是尝试填充a和b ：

filename = 'Folder/File%02d-%02d.file' % (a, b)

Answer 2

In computer languages, numbers are stored internally in binary and have no concept of formatting. 16, 0x10, 0b10000 are all ways to format the number 16.

Python has string formatting to help with this:

>>> x = 16
>>> format(x,'x') # format as hexadecimal
'10'
>>> format(x,'b') # format as binary
'10000'
>>> format(x,'#x') # hexadecimal with indicator
'0x10'
>>> format(x,'#b') # binary with indicator
'0b10000'
>>> format(x,'4') # decimal with minimal length 4
'  16'
>>> format(x,'04') # decimal with mimimal length 4 and leading zeroes
'0016'

You can embed formatting in a format string, and specify different formats for the same parameter by index. Below formats the first parameter (index 0) three different ways:

>>> '{0} {0:#x} {0:#b}'.format(16)
'16 0x10 0b10000'

In Python 3.6, there are new formatting strings that simplify the syntax:

>>> a,b,c=1,2,3
>>> f'{c} {b} {a:02}'
'3 2 01'

For your example:

filename = 'Folder/File{:02}-{:02}.file'.format(a,b)

See Format Specification Mini-Language .