Format in python by variable length

Question

I want to print a staircase-like pattern. I tried this using .format() method:

for i in range(6, 0, -1):
    print("{0:>"+str(i)+"}".format("#"))

But it gave me following error:

ValueError: Single '}' encountered in format string

Basically the idea is to print this output:

     #
    #
   #
  #
 #
#

Just add parenthesis around the string being constructed: print(("{0:>"+str(i)+"}").format("#")) — niemmi
– niemmi, Commented May 1, 2016 at 4:22
You can pass its value through format(): print("{0:>{1}}".format("#", i)) — Ashwini Chaudhary
– Ashwini Chaudhary, Commented May 1, 2016 at 4:22
@AshwiniChaudhary the # is fixed. So would it be possible to get it into the string instead of as a parameter? Like "{#:>{0}}".format(i), which doesn't work. — BlackShift
– BlackShift, Commented Jul 28, 2017 at 10:32
Near-duplicate: How can I fill out a Python string with spaces? — smci
– smci, Commented Jan 9, 2024 at 3:06

smci · Accepted Answer · 2024-01-09 21:25:49Z

20

Use f-strings

for i in range(6, 0, -1): 
    print(f"{'#':>{i}}")

or:

for i in range(6, 0, -1): 
    print("{0:>{1}}".format("#", i))

Both solutions give the output:

     #
    #
   #
  #
 #
#

smci

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answered Oct 10, 2019 at 23:49

Camion

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This obviously also works with f-strings: x = '#'; y = 3; z = f'{x:>{y}}'

EbraHim · Accepted Answer · 2016-05-01 04:31:52Z

7

Currently your code interpreted as below:

for i in range(6, 0, -1):
    print ( ("{0:>"+str(i))     +     ("}".format("#")))

So the format string is constructed of a single "}" and that's not correct. You need the following:

for i in range(6, 0, -1):
    print(("{0:>"+str(i)+"}").format("#"))

Works as you want:

================ RESTART: C:/Users/Desktop/TES.py ================
     #
    #
   #
  #
 #
#
>>>

answered May 1, 2016 at 4:31

EbraHim

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Yep, the '}'.format is the same as the typical some_object.method.