问题
Given:
a = 1
b = 10
c = 100
How do I display a leading zero for all numbers with less than two digits?
That is,
01
10
100
回答1:
In Python 2 you can do:
print "%02d" % (1,)
Basically % is like printf or sprintf.
For Python 3.+ the same behavior can be achieved with:
print("{:02d}".format(1))
For Python 3.6+ the same behavior can be achieved with f-strings:
print(f"{1:02d}")
回答2:
You can use str.zfill:
print str(1).zfill(2)
print str(10).zfill(2)
print str(100).zfill(2)
prints:
01
10
100
回答3:
In Python 2.6+ and 3.0+, you would use the format() string method:
for i in (1, 10, 100):
print('{num:02d}'.format(num=i))
or using the built-in (for a single number):
print(format(i, '02d'))
See the PEP-3101 documentation for the new formatting functions.
回答4:
print('{:02}'.format(1))
print('{:02}'.format(10))
print('{:02}'.format(100))
prints:
01
10
100
回答5:
Or this:
print '{0:02d}'.format(1)
回答6:
In Python >= 3.6, you can do this succinctly with the new f-strings that were introduced by using:
f'{val:02}'
which prints the variable with name val with a fill value of 0 and a width of 2.
For your specific example you can do this nicely in a loop:
a, b, c = 1, 10, 100
for val in [a, b, c]:
print(f'{val:02}')
which prints:
01
10
100
For more information on f-strings, take a look at PEP 498 where they were introduced.
回答7:
x = [1, 10, 100]
for i in x:
print '%02d' % i
results in:
01
10
100
Read more information about string formatting using % in the documentation.
回答8:
The Pythonic way to do this:
str(number).rjust(string_width, fill_char)
This way, the original string is returned unchanged if its length is greater than string_width. Example:
a = [1, 10, 100]
for num in a:
print str(num).rjust(2, '0')
Results:
01
10
100
回答9:
Or another solution.
"{:0>2}".format(number)
回答10:
Use a format string - http://docs.python.org/lib/typesseq-strings.html
For example:
python -c 'print "%(num)02d" % {"num":5}'
回答11:
This is how I do it:
str(1).zfill(len(str(total)))
Basically zfill takes the number of leading zeros you want to add, so it's easy to take the biggest number, turn it into a string and get the length, like this:
Python 3.6.5 (default, May 11 2018, 04:00:52) [GCC 8.1.0] on linux Type "help", "copyright", "credits" or "license" for more information. >>> total = 100 >>> print(str(1).zfill(len(str(total)))) 001 >>> total = 1000 >>> print(str(1).zfill(len(str(total)))) 0001 >>> total = 10000 >>> print(str(1).zfill(len(str(total)))) 00001 >>>
回答12:
width = 5
num = 3
formatted = (width - len(str(num))) * "0" + str(num)
print formatted
回答13:
Use:
'00'[len(str(i)):] + str(i)
Or with the math module:
import math
'00'[math.ceil(math.log(i, 10)):] + str(i)
回答14:
df['Col1']=df['Col1'].apply(lambda x: '{0:0>5}'.format(x)) (the 5 is the number of total digits)
I used this link: http://www.datasciencemadesimple.com/add-leading-preceding-zeros-python/
回答15:
If dealing with numbers that are either one or two digits:
'0'+str(number)[-2:] or '0{0}'.format(number)[-2:]
来源：https://stackoverflow.com/questions/134934/display-number-with-leading-zeros