String in Python (27)

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*Memos:

• 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() (5).
• My post explains f-strings.
• My post explains format().
• My post explains format_map().
• My post explains a string.

:[f][a][s][z][#][0][w][g][.p][t] can format a string as shown below. *Format Specification Mini-Language explains more details:

<Format a string with Decimal() by 'f' or 'F'>:

from decimal import Decimal

v = Decimal(value='1234.5555555555')
                      # |   10   |
print(v)
# 1234.5555555555
#      |   10   |

print(f'"{v:.20f}"')
print(f'"{v:.20F}"')
# "1234.55555555550000000000"
#       |        20        |

print(f'"{v:.15f}"')
print(f'"{v:.15F}"')
# "1234.555555555500000"
#       |     15      |

print(f'"{v:.10f}"')
print(f'"{v:.10F}"')
print(f'"{v:f}"')
print(f'"{v:F}"')
# "1234.5555555555"
#       |   10   |

print(f'"{v:.6f}"')
print(f'"{v:.6F}"')
# "1234.555556"
#       | 6  |

print(f'"{v:.2f}"')
print(f'"{v:.2F}"')
# "1234.56"

print(f'"{v:.1f}"')
print(f'"{v:.1F}"')
# "1234.6"

print(f'"{v:.0f}"')
print(f'"{v:.0F}"')
# "1235"

print(f'"{v:#.0f}"')
print(f'"{v:#.0F}"')
# "1235."

print(f'"{v:,.20f}"')
print(f'"{v:,.20F}"')
# "1,234.55555555550000000000"
#        |        20        |

print(f'"{v:,f}"')
print(f'"{v:,F}"')
# "1,234.5555555555"
#        |   10   |

print(f'"{v:_.20f}"')
print(f'"{v:_.20F}"')
print(f'"{v:_f}"')
print(f'"{v:_F}"')
# ValueError: invalid format string

from decimal import Decimal

v1 = Decimal(value='nan')
v2 = Decimal(value='inf')

print(f'"{v1:f} {v2:f}"')
print(f'"{v1:F} {v2:F}"')
# "NaN Infinity"

*Decimal() without str gets an improper value.

from decimal import Decimal

v = Decimal(value=1234.5555555555)
                     # |   10   |
print(v)
# 1234.555555555499950060038827359676361083984375
#      |                  42                    |

print(f'"{v:.20f}"')
print(f'"{v:.20F}"')
# "1234.55555555549995006004"
#       |        20        |

print(f'"{v:.15f}"')
print(f'"{v:.15F}"')
# "1234.555555555499950"
#       |     15      |

print(f'"{v:.10f}"')
print(f'"{v:.10F}"')
# "1234.5555555555"
#       |   10   |

print(f'"{v:.6f}"')
print(f'"{v:.6F}"')
# "1234.555556"
#       | 6  |

print(f'"{v:.2f}"')
print(f'"{v:.2F}"')
# "1234.56"

print(f'"{v:.1f}"')
print(f'"{v:.1F}"')
# "1234.6"

print(f'"{v:.0f}"')
print(f'"{v:.0F}"')
# "1235"

print(f'"{v:#.0f}"')
print(f'"{v:#.0F}"')
# "1235."

print(f'"{v:f}"')
print(f'"{v:F}"')
# "1234.555555555499950060038827359676361083984375"
#       |                  42                    |

print(f'"{v:,.20f}"')
print(f'"{v:,.20F}"')
# "1,234.55555555549995006004"
#        |        20        |

print(f'"{v:,f}"')
print(f'"{v:,F}"')
# "1,234.555555555499950060038827359676361083984375"
#       |                   42                    |

print(f'"{v:_.20f}"')
print(f'"{v:_.20F}"')
print(f'"{v:_f}"')
print(f'"{v:_F}"')
# ValueError: invalid format string

from decimal import Decimal

v1 = Decimal(value=float('nan'))
v2 = Decimal(value=float('inf'))

print(f'"{v1:f} {v2:f}"')
print(f'"{v1:F} {v2:F}"')
# "NaN Infinity"