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Merged
vstinner merged 16 commits into from
Feb 25, 2025
Merged

gh-87790: support thousands separators for formatting fractional part of floats #125304

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5858d8c
gh-87790: support underscore for formatting fractional part of floats
skirpichev Sep 21, 2024
d7b3784
put separators in fractional part, iterating from most significand digit
skirpichev Oct 11, 2024
5b70fff
address review: formatting
skirpichev Oct 12, 2024
42df636
Merge branch 'master' into fmt-frac-grouping-87790
skirpichev Nov 16, 2024
ca70d89
address review: check return value of PyUnicode_FromOrdinal()
skirpichev Nov 16, 2024
28b9137
address review: support comma
skirpichev Nov 16, 2024
0a0b3b0
address review: fix error handling
skirpichev Nov 16, 2024
59aab3c
add examples
skirpichev Nov 16, 2024
02d44de
address review: merge examples for comma/underscore
skirpichev Nov 16, 2024
4d32cd5
Merge branch 'master' into fmt-frac-grouping-87790
skirpichev Nov 18, 2024
e359616
address review: forbid separators for ``n``
skirpichev Nov 18, 2024
ea851c3
address review: more tests
skirpichev Nov 18, 2024
4d3f0e3
address review: add to whatsnew
skirpichev Nov 18, 2024
c008a6e
Merge branch 'main' into fmt-frac-grouping-87790
skirpichev Feb 7, 2025
1c36219
Merge branch 'master' into fmt-frac-grouping-87790
skirpichev Feb 8, 2025
893421d
address review: format-spec & more tests
skirpichev Feb 8, 2025
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address review: support comma
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@skirpichev
skirpichev committed Nov 16, 2024
commit 28b91378bd4552a1159526cc0a8e7b4b5d8b7bfd
11 changes: 5 additions & 6 deletions Doc/library/string.rst
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Expand Up @@ -312,13 +312,12 @@ non-empty format specification typically modifies the result.
The general form of a *standard format specifier* is:

.. productionlist:: format-spec
format_spec: [[`fill`]`align`][`sign`]["z"]["#"]["0"][`width`][`grouping_option`]["." `precision` [`fraction_grouping`]][`type`]
format_spec: [[`fill`]`align`][`sign`]["z"]["#"]["0"][`width`][`grouping_option`]["." `precision` [`grouping_option`]][`type`]

@serhiy-storchaka serhiy-storchaka Nov 18, 2024

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This is not accurate. More accurate would be ["." `precision` [`grouping_option`] | "." `grouping_option`] or ["." (`precision` [`grouping_option`] | `grouping_option`)] or ["." [`precision`][`grouping_option`]] with addition that either precision or grouping_option should be specified after ".".

@skirpichev skirpichev Nov 19, 2024 •
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How about this:

.. productionlist:: format-spec
   format_spec: [`options`][`width_and_precision`][`type`]
   options: [[`fill`]`align`][`sign`]["z"]["#"]["0"]
   fill: <any character>
   align: "<" | ">" | "=" | "^"
   sign: "+" | "-" | " "
   width_and_precision: [`width_with_grouping`][`precision_with_grouping`]
   width_with_grouping: [`width`][`grouping_option`]
   precision_with_grouping: "." (`precision`[`grouping_option`] | `grouping_option`)
   width: `~python-grammar:digit`+
   grouping_option: "_" | ","
   precision: `~python-grammar:digit`+
   type: "b" | "c" | "d" | "e" | "E" | "f" | "F" | "g"
       : | "G" | "n" | "o" | "s" | "x" | "X" | "%"

?

@serhiy-storchaka serhiy-storchaka Feb 7, 2025

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Redundant [...] in precision_with_grouping.

@skirpichev skirpichev Feb 7, 2025

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Updated.

fill: <any character>
align: "<" | ">" | "=" | "^"
sign: "+" | "-" | " "
width: `~python-grammar:digit`+
grouping_option: "_" | ","
fraction_grouping: "_"
precision: `~python-grammar:digit`+
type: "b" | "c" | "d" | "e" | "E" | "f" | "F" | "g" | "G" | "n" | "o" | "s" | "x" | "X" | "%"

Expand Down Expand Up @@ -450,12 +449,12 @@ indicates the maximum field size - in other words, how many characters will be
used from the field content. The *precision* is not allowed for integer
presentation types.

The ``'_'`` option after *precision* means the use of an underscore for a
thousands separator of the fractional part for floating-point presentation
types.
The ``'_'`` or ``','`` option after *precision* means the use of an underscore
or a comma for a thousands separator of the fractional part for floating-point
presentation types.

.. versionchanged:: 3.14
Support underscore as a thousands separator for the fractional part.
Support thousands separators for the fractional part.

Finally, the *type* determines how the data should be presented.

Expand Down
1 change: 1 addition & 0 deletions Lib/test/test_float.py
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Expand Up @@ -763,6 +763,7 @@ def test_format(self):
self.assertEqual(format(x, '>21._f'), ' 123456.123_456')
self.assertEqual(format(x, '<21._f'), '123456.123_456 ')
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self.assertEqual(format(x, '+.11_e'), '+1.234_561_234_56e+05')
self.assertEqual(format(x, '+.11,e'), '+1.234,561,234,56e+05')

self.assertRaises(ValueError, format, x , '._6f')

Expand Down
2 changes: 1 addition & 1 deletion Misc/NEWS.d/next/Core_and_Builtins/2024-10-11-10-41-05.gh-issue-87790.mlfEGl.rst
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@@ -1,3 +1,3 @@
Support underscore as a thousands separator in the fractional part for
Support underscore and comma as thousands separators in the fractional part for
floating-point presentation types of the new-style string formatting (with
:func:`format` or :ref:`f-strings`). Patch by Sergey B Kirpichev.
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15 changes: 13 additions & 2 deletions Python/formatter_unicode.c
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Expand Up @@ -270,6 +270,16 @@ parse_internal_render_format_spec(PyObject *obj,
++pos;
++consumed;
}
if (end-pos && READ_spec(pos) == ','
&& format->frac_thousands_separator == LT_NO_LOCALE)
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{
if (consumed == 0) {
format->precision = -1;
}
format->frac_thousands_separator = LT_DEFAULT_LOCALE;
++pos;
++consumed;
}

/* Not having a precision or underscore after a dot is an error. */
if (consumed == 0) {
Expand Down Expand Up @@ -800,8 +810,9 @@ get_locale_info(enum LocaleType type, enum LocaleType frac_type,
locale_info->grouping = no_grouping;
break;
}
if (frac_type == LT_UNDERSCORE_LOCALE) {
locale_info->frac_thousands_sep = PyUnicode_FromOrdinal('_');
if (frac_type != LT_NO_LOCALE) {
locale_info->frac_thousands_sep = PyUnicode_FromOrdinal(
frac_type == LT_DEFAULT_LOCALE ? ',' : '_');
if (!locale_info->frac_thousands_sep) {
return -1;
}
Expand Down