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How do I recognize one digit in a string to insert a leading zero?

In Python, I have a string with two digits or one digit:

8 5E 9C 52 30 0

On every single line in a line, I would like to add zero to it (like convert 5

to 05

) and make two digits.

We think of the division, .split(‘ ‘)

and check each one and transform each number in two digits using: .zfill(2)

.

So my question is, is there a way to recognize all one digit in a string and convert all of them to two digits by inserting a leading zero?

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4 answers


Well, the good thing about zfill(..)

is that if the content contains two characters, that line is left untouched. So you can just use a generator (or list comprehension) and the ' '.join(..)

result back:

result = ' '.join(x.zfill(2) for x in data.split())


What generates:

>>> data = '8 5E 9C 52 30 0'
>>> ' '.join(x.zfill(2) for x in data.split())
'08 5E 9C 52 30 00'
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Simple solution with a list.

Code:

def pad_hex_str(hex):
    return ' '.join(['0' + h if len(h) == 1 else h for h in hex.split()])

Test code:



hex_str = '8 5E 9C 52 30 0'
print(pad_hex_str(hex_str))

Results:

08 5E 9C 52 30 00
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split

and use zfill

will work fine.

st = "8 5E 9C 52 30 0"
res = ""
for i in st.split():
        res += " " + i.zfill(2)  
print res

#output
08 5E 9C 52 30 00
0


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>>> re.sub(r'(\b\d\b)', r'0\1', string)
>>> '08 5E 9C 52 30 00'

Don't forget to re-import, of course

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