Method _float_precision_changed

IPython/core/formatters.py:626–670

float_precision changed, set float_format accordingly. float_precision can be set by int or str. This will set float_format, after interpreting input. If numpy has been imported, numpy print precision will also be set. integer `n` sets format to '%.nf', otherwise, f

(self, change)

    @observe('float_precision')
    def _float_precision_changed(self, change):
        """float_precision changed, set float_format accordingly.

        float_precision can be set by int or str.
        This will set float_format, after interpreting input.
        If numpy has been imported, numpy print precision will also be set.

        integer `n` sets format to '%.nf', otherwise, format set directly.

        An empty string returns to defaults (repr for float, 8 for numpy).

        This parameter can be set via the '%precision' magic.
        """

        new = change['new']
        if '%' in new:
            # got explicit format string
            fmt = new
            try:
                fmt%3.14159
            except Exception:
                raise ValueError("Precision must be int or format string, not %r"%new)
        elif new:
            # otherwise, should be an int
            try:
                i = int(new)
                assert i >= 0
            except ValueError:
                raise ValueError("Precision must be int or format string, not %r"%new)
            except AssertionError:
                raise ValueError("int precision must be non-negative, not %r"%i)

            fmt = '%%.%if'%i
            if 'numpy' in sys.modules:
                # set numpy precision if it has been imported
                import numpy
                numpy.set_printoptions(precision=i)
        else:
            # default back to repr
            fmt = '%r'
            if 'numpy' in sys.modules:
                import numpy
                # numpy default is 8
                numpy.set_printoptions(precision=8)
        self.float_format = fmt

    # Use the default pretty printers from IPython.lib.pretty.
    @default('singleton_printers')