Update doc.
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Victor Zverovich
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doc/string.rst
211
doc/string.rst
@ -184,7 +184,7 @@ The general form of a *standard format specifier* is:
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align: "<" | ">" | "=" | "^"
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sign: "+" | "-" | " "
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width: `integer`
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precision: `integer`
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precision: `integer` | "{" `arg_index` "}"
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type: "c" | "d" | "e" | "E" | "f" | "F" | "g" | "G" | "o" | "p" | s" | "x" | "X"
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The *fill* character can be any character other than '{' or '}'. The presence
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@ -299,21 +299,16 @@ The available integer presentation types are:
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+---------+----------------------------------------------------------+
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| ``'o'`` | Octal format. Outputs the number in base 8. |
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+---------+----------------------------------------------------------+
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| ``'x'`` | Hex format. Outputs the number in base 16, using lower- |
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| | case letters for the digits above 9. |
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| ``'x'`` | Hex format. Outputs the number in base 16, using |
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| | lower-case letters for the digits above 9. |
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+---------+----------------------------------------------------------+
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| ``'X'`` | Hex format. Outputs the number in base 16, using upper- |
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| | case letters for the digits above 9. |
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| ``'X'`` | Hex format. Outputs the number in base 16, using |
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| | upper-case letters for the digits above 9. |
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+---------+----------------------------------------------------------+
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| none | The same as ``'d'``. |
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+---------+----------------------------------------------------------+
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In addition to the above presentation types, integers can be formatted
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with the floating point presentation types listed below (except
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``'n'`` and none). When doing so, :func:`float` is used to convert the
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integer to a floating point number before formatting.
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The available presentation types for floating point and decimal values are:
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The available presentation types for floating point values are:
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+---------+----------------------------------------------------------+
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| Type | Meaning |
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@ -335,6 +330,19 @@ The available presentation types for floating point and decimal values are:
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| | then formats the result in either fixed-point format |
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| | or in scientific notation, depending on its magnitude. |
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| | |
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| | A precision of ``0`` is treated as equivalent to a |
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| | precision of ``1``. |
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+---------+----------------------------------------------------------+
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| ``'G'`` | General format. Same as ``'g'`` except switches to |
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| | ``'E'`` if the number gets too large. The |
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| | representations of infinity and NaN are uppercased, too. |
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+---------+----------------------------------------------------------+
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| none | The same as ``'g'``. |
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+---------+----------------------------------------------------------+
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.. ifconfig:: False
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+---------+----------------------------------------------------------+
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| | The precise rules are as follows: suppose that the |
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| | result formatted with presentation type ``'e'`` and |
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| | precision ``p-1`` would have exponent ``exp``. Then |
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@ -351,17 +359,17 @@ The available presentation types for floating point and decimal values are:
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| | ``0``, ``-0`` and ``nan`` respectively, regardless of |
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| | the precision. |
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| | |
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| | A precision of ``0`` is treated as equivalent to a |
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| | precision of ``1``. |
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+---------+----------------------------------------------------------+
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| ``'G'`` | General format. Same as ``'g'`` except switches to |
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| | ``'E'`` if the number gets too large. The |
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| | representations of infinity and NaN are uppercased, too. |
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The available presentation types for pointers are:
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+---------+----------------------------------------------------------+
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| none | Similar to ``'g'``, except with at least one digit past |
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| | the decimal point and a default precision of 12. This is |
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| | intended to match :func:`str`, except you can add the |
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| | other format modifiers. |
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| Type | Meaning |
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+=========+==========================================================+
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| ``'p'`` | Pointer format. This is the default type for |
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| | pointers and may be omitted. |
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+---------+----------------------------------------------------------+
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| none | The same as ``'p'``. |
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+---------+----------------------------------------------------------+
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@ -370,117 +378,102 @@ The available presentation types for floating point and decimal values are:
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Format examples
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^^^^^^^^^^^^^^^
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This section contains examples of the new format syntax and comparison with
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the old ``%``-formatting.
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This section contains examples of the format syntax and comparison with
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the printf formatting.
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In most of the cases the syntax is similar to the old ``%``-formatting, with the
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In most of the cases the syntax is similar to the printf formatting, with the
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addition of the ``{}`` and with ``:`` used instead of ``%``.
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For example, ``'%03.2f'`` can be translated to ``'{:03.2f}'``.
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For example, ``"%03.2f"`` can be translated to ``"{:03.2f}"``.
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The new format syntax also supports new and different options, shown in the
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follow examples.
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following examples.
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Accessing arguments by position::
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>>> '{0}, {1}, {2}'.format('a', 'b', 'c')
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'a, b, c'
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>>> '{}, {}, {}'.format('a', 'b', 'c') # 3.1+ only
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'a, b, c'
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>>> '{2}, {1}, {0}'.format('a', 'b', 'c')
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'c, b, a'
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>>> '{2}, {1}, {0}'.format(*'abc') # unpacking argument sequence
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'c, b, a'
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>>> '{0}{1}{0}'.format('abra', 'cad') # arguments' indices can be repeated
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'abracadabra'
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Accessing arguments by name::
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>>> 'Coordinates: {latitude}, {longitude}'.format(latitude='37.24N', longitude='-115.81W')
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'Coordinates: 37.24N, -115.81W'
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>>> coord = {'latitude': '37.24N', 'longitude': '-115.81W'}
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>>> 'Coordinates: {latitude}, {longitude}'.format(**coord)
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'Coordinates: 37.24N, -115.81W'
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Accessing arguments' items::
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>>> coord = (3, 5)
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>>> 'X: {0[0]}; Y: {0[1]}'.format(coord)
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'X: 3; Y: 5'
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Format("{0}, {1}, {2}") << 'a' << 'b' << 'c';
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// Result: "a, b, c"
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Format("{}, {}, {}") << 'a' << 'b' << 'c';
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// Result: "a, b, c"
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Format("{2}, {1}, {0}") << 'a' << 'b' << 'c';
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// Result: "c, b, a"
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Format("{0}{1}{0}" << "abra" << "cad"; // arguments' indices can be repeated
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// Result: "abracadabra"
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Aligning the text and specifying a width::
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>>> '{:<30}'.format('left aligned')
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'left aligned '
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>>> '{:>30}'.format('right aligned')
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' right aligned'
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>>> '{:^30}'.format('centered')
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' centered '
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>>> '{:*^30}'.format('centered') # use '*' as a fill char
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'***********centered***********'
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Format("{:<30}") << "left aligned";
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// Result: "left aligned "
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Format("{:>30}") << "right aligned"
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// Result: " right aligned"
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Format("{:^30}") << "centered"
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// Result: " centered "
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Format("{:*^30}") << "centered" // use '*' as a fill char
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// Result: "***********centered***********"
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Replacing ``%+f``, ``%-f``, and ``% f`` and specifying a sign::
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>>> '{:+f}; {:+f}'.format(3.14, -3.14) # show it always
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'+3.140000; -3.140000'
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>>> '{: f}; {: f}'.format(3.14, -3.14) # show a space for positive numbers
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' 3.140000; -3.140000'
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>>> '{:-f}; {:-f}'.format(3.14, -3.14) # show only the minus -- same as '{:f}; {:f}'
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'3.140000; -3.140000'
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Format("{:+f}; {:+f}") << 3.14 << -3.14; // show it always
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// Result: "+3.140000; -3.140000"
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Format("{: f}; {: f}") << 3.14 << -3.14; // show a space for positive numbers
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// Result: " 3.140000; -3.140000"
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Format("{:-f}; {:-f}") << 3.14 << -3.14; // show only the minus -- same as '{:f}; {:f}'
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// Result: "3.140000; -3.140000"
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Replacing ``%x`` and ``%o`` and converting the value to different bases::
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>>> # format also supports binary numbers
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>>> "int: {0:d}; hex: {0:x}; oct: {0:o}; bin: {0:b}".format(42)
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'int: 42; hex: 2a; oct: 52; bin: 101010'
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>>> # with 0x, 0o, or 0b as prefix:
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>>> "int: {0:d}; hex: {0:#x}; oct: {0:#o}; bin: {0:#b}".format(42)
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'int: 42; hex: 0x2a; oct: 0o52; bin: 0b101010'
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Format("int: {0:d}; hex: {0:x}; oct: {0:o}") << 42;
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// Result: "int: 42; hex: 2a; oct: 52"
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// with 0x or 0 as prefix:
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Format("int: {0:d}; hex: {0:#x}; oct: {0:#o}") << 42;
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// Result: "int: 42; hex: 0x2a; oct: 052"
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Using the comma as a thousands separator::
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.. ifconfig:: False
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>>> '{:,}'.format(1234567890)
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'1,234,567,890'
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Using the comma as a thousands separator::
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Expressing a percentage::
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Format("{:,}") << 1234567890)
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'1,234,567,890'
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>>> points = 19
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>>> total = 22
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>>> 'Correct answers: {:.2%}'.format(points/total)
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'Correct answers: 86.36%'
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Expressing a percentage::
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Using type-specific formatting::
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>>> points = 19
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>>> total = 22
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Format("Correct answers: {:.2%}") << points/total)
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'Correct answers: 86.36%'
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>>> import datetime
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>>> d = datetime.datetime(2010, 7, 4, 12, 15, 58)
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>>> '{:%Y-%m-%d %H:%M:%S}'.format(d)
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'2010-07-04 12:15:58'
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Using type-specific formatting::
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Nesting arguments and more complex examples::
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>>> import datetime
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>>> d = datetime.datetime(2010, 7, 4, 12, 15, 58)
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Format("{:%Y-%m-%d %H:%M:%S}") << d)
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'2010-07-04 12:15:58'
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>>> for align, text in zip('<^>', ['left', 'center', 'right']):
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... '{0:{fill}{align}16}'.format(text, fill=align, align=align)
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...
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'left<<<<<<<<<<<<'
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'^^^^^center^^^^^'
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'>>>>>>>>>>>right'
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>>>
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>>> octets = [192, 168, 0, 1]
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>>> '{:02X}{:02X}{:02X}{:02X}'.format(*octets)
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'C0A80001'
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>>> int(_, 16)
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3232235521
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>>>
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>>> width = 5
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>>> for num in range(5,12):
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... for base in 'dXob':
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... print('{0:{width}{base}}'.format(num, base=base, width=width), end=' ')
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... print()
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...
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5 5 5 101
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6 6 6 110
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7 7 7 111
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8 8 10 1000
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9 9 11 1001
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10 A 12 1010
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11 B 13 1011
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Nesting arguments and more complex examples::
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>>> for align, text in zip('<^>', ['left', 'center', 'right']):
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... '{0:{fill}{align}16}") << text, fill=align, align=align)
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...
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'left<<<<<<<<<<<<'
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'^^^^^center^^^^^'
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'>>>>>>>>>>>right'
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>>>
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>>> octets = [192, 168, 0, 1]
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Format("{:02X}{:02X}{:02X}{:02X}") << *octets)
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'C0A80001'
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>>> int(_, 16)
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3232235521
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>>>
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>>> width = 5
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>>> for num in range(5,12):
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... for base in 'dXob':
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... print('{0:{width}{base}}") << num, base=base, width=width), end=' ')
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... print()
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...
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5 5 5 101
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6 6 6 110
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7 7 7 111
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8 8 10 1000
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9 9 11 1001
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10 A 12 1010
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11 B 13 1011
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