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Document the different meaning of precision for {:f} and {:g}. 

Also document how inf and nan are formatted. #3404.
This commit is contained in:
Georg Brandl 2008-07-18 11:15:06 +00:00
parent 730c8185b9
commit bf89981839
1 changed files with 12 additions and 8 deletions
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Doc/library/string.rst
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@ -387,10 +387,11 @@ zero-padding. This is equivalent to an *alignment* type of ``'='`` and a *fill*
character of ``'0'``.
The *precision* is a decimal number indicating how many digits should be
displayed after the decimal point for a floating point value. For non-number
types the field indicates the maximum field size - in other words, how many
characters will be used from the field content. The *precision* is ignored for
integer values.
displayed after the decimal point for a floating point value formatted with
``'f'`` and ``'F'``, or before and after the decimal point for a floating point
value formatted with ``'g'`` or ``'G'``. For non-number types the field
indicates the maximum field size - in other words, how many characters will be
used from the field content. The *precision* is ignored for integer values.
Finally, the *type* determines how the data should be presented.
@ -418,7 +419,7 @@ The available integer presentation types are:
| | the current locale setting to insert the appropriate |
| | number separator characters. |
+---------+----------------------------------------------------------+
| None | the same as ``'d'`` |
| None | The same as ``'d'``. |
+---------+----------------------------------------------------------+
The available presentation types for floating point and decimal values are:
@ -439,10 +440,13 @@ The available presentation types for floating point and decimal values are:
+---------+----------------------------------------------------------+
| ``'g'`` | General format. This prints the number as a fixed-point |
| | number, unless the number is too large, in which case |
| | it switches to ``'e'`` exponent notation. |
| | it switches to ``'e'`` exponent notation. Infinity and |
| | NaN values are formatted as ``inf``, ``-inf`` and |
| | ``nan``, respectively. |
+---------+----------------------------------------------------------+
| ``'G'`` | General format. Same as ``'g'`` except switches to |
| | ``'E'`` if the number gets to large. |
| | ``'E'`` if the number gets to large. The representations |
| | of infinity and NaN are uppercased, too. |
+---------+----------------------------------------------------------+
| ``'n'`` | Number. This is the same as ``'g'``, except that it uses |
| | the current locale setting to insert the appropriate |
@ -451,7 +455,7 @@ The available presentation types for floating point and decimal values are:
| ``'%'`` | Percentage. Multiplies the number by 100 and displays |
| | in fixed (``'f'``) format, followed by a percent sign. |
+---------+----------------------------------------------------------+
| None | the same as ``'g'`` |
| None | The same as ``'g'``. |
+---------+----------------------------------------------------------+