*Memo:
- My post explains Format Specification with format() (1).
- My post explains Format Specification with format() (2).
- My post explains Format Specification with format() (3).
- My post explains Format Specification with format() (4).
- My post explains Format Specification with format() (5).
- My post explains f-strings.
- My post explains format_map().
- My post explains a string.
format() can create a string with zero or more positional and/or keyword arguments, then format the string as shown below:
*Memo:
- The 1st arguments are
*args(Optional-Default:()-Type:Any):- Don't use any keyword like
*args,args, etc.
- Don't use any keyword like
- The 2nd arguments are
**kwargs(Optional-Default:{}-Type:Any):- Don't use any keyword like
**kwargs,kwargs, etc.
- Don't use any keyword like
<{} & {index} & {key}>:
*Memo:
- A
{}can output a positional argument with limit:- For example, if there are three positional arguments, three
{}can be used as maximum.
- For example, if there are three positional arguments, three
- A
{index}can output a positional argument with no limit. - A
{key}can output a keyword argument with no limit. - Both
{}and{index}cannot be used at the same time. -
{}doesn't accept any spaces.
print('-{}-{}-{}-{k1}-{k2}-'.format('A', 'BC', 'DEF', k1='GH', k2='I')) print('-{0}-{1}-{2}-{k1}-{k2}-'.format('A', 'BC', 'DEF', k1='GH', k2='I')) # -A-BC-DEF-GH-I- print('-{}-{k2}-{}-{k1}-{}-'.format('A', 'BC', 'DEF', k1='GH', k2='I')) print('-{0}-{k2}-{1}-{k1}-{2}-'.format('A', 'BC', 'DEF', k1='GH', k2='I')) # -A-I-BC-GH-DEF- print('-{k2}-{k1}-{2}-{1}-{0}-'.format('A', 'BC', 'DEF', k1='GH', k2='I')) # -I-GH-DEF-BC-A- print('-{1}{0}-{k2}{0}{1}-{2}{2}-'.format('A', 'BC', 'DEF', k1='GH', k2='I')) # -BCA-IABC-DEFDEF- print(''.format('A', 'BC', 'DEF', k1='GH', k2='I')) print(''.format()) # Nothing print('-{}-{}-{}-{}-'.format('A', 'BC', 'DEF', k1='GH', k2='I')) # IndexError: Replacement index 3 out of range for positional args tuple print('-{0}-{}-{2}-'.format('A', 'BC', 'DEF', k1='GH', k2='I')) # ValueError: cannot switch from manual field specification # to automatic field numbering print('{ }'.format('ABC')) # KeyError: ' ' print('{ k }'.format(k='ABC')) # KeyError: ' k ' v1 = ['A', 'BC', 'DEF'] v2 = {'k1':'GH', 'k2':'I'} print('-{}-{}-{}-{k1}-{k2}-'.format(*v1, **v2)) print('-{0}-{1}-{2}-{k1}-{k2}-'.format(*v1, **v2)) # -A-BC-DEF-GH-I- print('-{}-{k2}-{}-{k1}-{}-'.format(*v1, **v2)) print('-{0}-{k2}-{1}-{k1}-{2}-'.format(*v1, **v2)) # -A-I-BC-GH-DEF- print('-{k2}-{k1}-{2}-{1}-{0}-'.format(*v1, **v2)) # -I-GH-DEF-BC-A- print('-{1}{0}-{k2}{0}{1}-{2}{2}-'.format(*v1, **v2)) # -BCA-IABC-DEFDEF- print(''.format(*v1, **v2)) print(''.format()) # Nothing *Format Specification can be used with format():
v = -0.0 print('"{:0>-z#010_.0f}"'.format(v)) print('"{:0>-z#10_.0f}"'.format(v)) print('"{:>-z#010_.0f}"'.format(v)) # "000000000." print('"{0:0>-z#010_.0f}"'.format(v)) print('"{0:0>-z#10_.0f}"'.format(v)) print('"{0:>-z#010_.0f}"'.format(v)) # "000000000." print('"{:0>-z#010_.0f}" "{:0>-z#10_.0f}" "{:>-z#010_.0f}"'.format(v, v, v)) print('"{0:0>-z#010_.0f}" "{1:0>-z#10_.0f}" "{2:>-z#010_.0f}"'.format(v, v, v)) # "000000000." "000000000." "000000000." <index[index] & key[index]>:
v = ['A', 'B', 'C', 'D'] print('{0}\n- {0[0]} - {0[1]} - {0[2]} - {0[3]}'.format(v)) print('{k}\n- {k[0]} - {k[1]} - {k[2]} - {k[3]}'.format(k=v)) # ['A', 'B', 'C', 'D'] # - A - B - C - D v1 = [['A', 'B'], ['C', 'D']] v2 = '{0}\n- {0[0]} - {0[1]}\n- {0[0][0]} - {0[0][1]} - {0[1][0]} - {0[1][1]}' v3 = '{k}\n- {k[0]} - {k[1]}\n- {k[0][0]} - {k[0][1]} - {k[1][0]} - {k[1][1]}' print(v2.format(v1)) print(v3.format(k=v1)) # [['A', 'B'], ['C', 'D']] # - ['A', 'B'] - ['C', 'D'] # - A - B - C - D <index[key] & key[key]>:
*key cannot have "" or ''.
v = {'name':'John', 'age':36} print('{0}\n- {0[name]} - {0[age]}'.format(v)) print('{k}\n- {k[name]} - {k[age]}'.format(k=v)) # {'name': 'John', 'age': 36} # - John - 36 print('{0["name"]}'.format(v)) # KeyError: '"name"' print("{k['age']}".format(k=v)) # KeyError: "'age'" v1 = {'person':{'name':'John', 'age':36}} v2 = '{0}\n- {0[person]}\n- {0[person][name]} - {0[person][age]}' v3 = '{k}\n- {k[person]}\n- {k[person][name]} - {k[person][age]}' print(v2.format(v1)) print(v3.format(k=v1)) # {'person': {'name': 'John', 'age': 36}} # - {'name': 'John', 'age': 36} # - John - 36 <index.key & key.key>:
*key cannot be called with ().
import math print('{0.pi} - {k.pi}'.format(math, k=math)) # 3.141592653589793 - 3.141592653589793 print('{0.pow}'.format(math)) print('{k.pow}'.format(k=math)) # <built-in function pow> print('{0.pow(3, 2)}'.format(math)) print('{k.pow(3, 2)}'.format(k=math)) # AttributeError: module 'math' has no attribute 'pow(3, 2)' <!s & !r & !a>:
*Memo:
-
!sis str() which can create a string. -
!ris repr() which can create a printable string. -
!ais ascii() which can create the printable string of ASCII characters. *Non-ASCII characters are represented with\x,\u, or\Uescape.
v = "Jφhи\tSмiтh" print("{!s}".format(v)) print("{0!s}".format(v)) print("{k!s}".format(k=v)) # Jφhи Sмiтh print("{!r}".format(v)) print("{0!r}".format(v)) print("{k!r}".format(k=v)) # 'Jφhи\tSмiтh' print("{!a}".format(v)) print("{0!a}".format(v)) print("{k!a}".format(k=v)) # 'J\u03c6h\u0438\tS\u043ci\u0442h' v = 'I\'m Jφhи\tSмiтh.' print('{!s}'.format(v)) print('{0!s}'.format(v)) print('{k!s}'.format(k=v)) # I'm Jφhи Sмiтh. print('{!r}'.format(v)) print('{0!r}'.format(v)) print('{k!r}'.format(k=v)) # "I'm Jφhи\tSмiтh." print('{!a}'.format(v)) print('{0!a}'.format(v)) print('{k!a}'.format(k=v)) # "I'm J\u03c6h\u0438\tS\u043ci\u0442h." <{{ & }}>
*Memo:
-
{can escape{. -
}can escape}.
print('The bracket {{ is escaped.'.format()) # The bracket { is escaped. print('The bracket }} is escaped.'.format()) # The bracket } is escaped. print('The {{brackets}} are escaped.'.format()) # The {brackets} are escaped. 
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