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Trac #30755: control the number of digits to display in matrices via IPython's %precision magic
Based on #30552, this ticket adds options for customizing the number of floating point digits to display in matrices. This is particularly useful for numeric computations involving large matrices. The option is linked to the IPython magic [https://ipython.readthedocs.io/en/stable/interactive/magics.html#magic- precision %precision]. (The IPython magic also sets the corresponding option in !NumPy.) {{{ sage: %precision 4 '%.4f' sage: A = matrix.random(RDF, 5); A [-0.01337 -0.9269 -0.0893 0.1784 0.975] [ 0.2152 0.6165 0.4195 0.7558 -0.9292] [ 0.8234 -0.2305 0.83 -0.9375 0.4938] [ -0.6378 0.7058 0.1209 -0.9081 -0.9551] [ 0.9217 -0.3054 -0.2997 0.5871 -0.5642] sage: %precision '%r' sage: A [-0.013365510514271595 -0.9268868721196306 -0.08930150422327143 0.17839999989498323 0.9750196839071508] [ 0.21517169403284941 0.6165223907365385 0.4195049240955384 0.7557760012777428 -0.9291629307331721] [ 0.8233703740645537 -0.23053733934301857 0.8299695817296515 -0.9375095363818953 0.4937640499860838] [ -0.6378186095056861 0.7057551432596336 0.12087801033553447 -0.9080993678019631 -0.9551440194578318] [ 0.9216765622236254 -0.30541498083145413 -0.29967291645930083 0.5871367386637378 -0.5642041854379536] }}} URL: https://trac.sagemath.org/30755 Reported by: gh-mwageringel Ticket author(s): Markus Wageringel Reviewer(s): David Ayotte
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‎src/sage/matrix/constructor.pyx

+38
Original file line numberDiff line numberDiff line change
@@ -669,6 +669,30 @@ class options(GlobalOptions):
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sage: matrix(ZZ, 4, 6)
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4 x 6 dense matrix over Integer Ring...
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sage: matrix.options._reset()
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The precision can also be set via the IPython magic::
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sage: from sage.repl.interpreter import get_test_shell
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sage: shell = get_test_shell()
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sage: shell.run_cell('%precision 5')
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'%.5f'
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sage: matrix.options.precision
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5
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sage: A = matrix(RR, [[200/3]]); A
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[66.667]
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The number format can be specified as well::
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sage: matrix.options.format_numeric = '{:.{prec}e}'
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sage: A
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[6.66667e+1]
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sage: matrix.options.format_numeric = '{:.{prec}f}'
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sage: A
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[66.66667]
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sage: matrix.options.format_numeric = '{:+.{prec}g}'
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sage: A
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[+66.667]
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sage: matrix.options._reset()
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"""
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NAME = 'Matrix'
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max_cols = dict(default=49,
@@ -677,3 +701,17 @@ class options(GlobalOptions):
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max_rows = dict(default=19,
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description='maximum number of rows to display',
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checker=lambda val: val >= 0)
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precision = \
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dict(default=None,
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description='number of digits to display for floating point '
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'entries; if ``None``, the exact representation is '
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'used instead. This option is also set by the '
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'`IPython magic <https://ipython.readthedocs.io/en/stable/interactive/magics.html#magic-precision>`_ '
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'``%precision``.',
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checker=lambda val: val is None or val >= 0)
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format_numeric = \
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dict(default='{:.{prec}}',
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description='string used for formatting floating point numbers of'
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' an (optional) precision ``prec``; only supported '
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'for entry types implementing ``__format__``',
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checker=lambda val: isinstance(val.format(3.1415, prec=3), str))

‎src/sage/matrix/matrix0.pyx

+48-1
Original file line numberDiff line numberDiff line change
@@ -1875,6 +1875,25 @@ cdef class Matrix(sage.structure.element.Matrix):
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-0.35104242112828943 0.5084492941557279⎟
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-0.9541798283979341 -0.8948790563276592⎠
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The number of floating point digits to display is controlled by
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:obj:`matrix.options.precision <.constructor.options>` and can also be
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set by the `IPython magic
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<https://ipython.readthedocs.io/en/stable/interactive/magics.html#magic-precision>`_
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``%precision``. This does not affect the internal precision of the
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represented data, but only the textual display of matrices::
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sage: matrix.options.precision = 4
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sage: A = matrix(RR, [[1/3, 200/3], [-3, 1e6]]); A
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[ 0.3333 66.67]
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[ -3.000 1.000E+6]
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sage: unicode_art(A)
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⎛ 0.3333 66.67⎞
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⎝ -3.000 1.000E+6⎠
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sage: matrix.options.precision = None
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sage: A
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[ 0.333333333333333 66.6666666666667]
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[ -3.00000000000000 1.00000000000000e6]
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TESTS:
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Prior to :trac:`11544` this could take a full minute to run (2011). ::
@@ -1898,6 +1917,19 @@ cdef class Matrix(sage.structure.element.Matrix):
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⎛─⎞
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⎜1⎟
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⎝─⎠
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Check that exact number types are not affected by the precision
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option::
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sage: matrix.options.precision = 4
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sage: matrix(ZZ, [[10^10]])
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[10000000000]
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sage: matrix(QQ, [[2/3, 10^6]])
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[ 2/3 1000000]
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sage: R.<x,y> = QQ[[]]
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sage: matrix(R, [[2/3 - 10^6 * x^3 + 3 * y + O(x, y)^4]])
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[2/3 + 3*y - 1000000*x^3 + O(x, y)^4]
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sage: matrix.options._reset()
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"""
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cdef Py_ssize_t nr, nc, r, c
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nr = self._nrows
@@ -1988,15 +2020,30 @@ cdef class Matrix(sage.structure.element.Matrix):
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if minus_one is not None:
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rep_mapping[-self.base_ring().one()] = minus_one
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entries = self.list()
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# only use floating point formatting for inexact types that have
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# custom implementation of __format__
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from .constructor import options
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prec = options.precision()
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if prec is None or callable(rep_mapping) or not entries \
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or type(entries[0]).__format__ is Element.__format__ \
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or self._base_ring.is_exact():
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fmt_numeric = None
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else:
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fmt_numeric = options.format_numeric()
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# compute column widths
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S = []
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for x in self.list():
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for x in entries:
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# Override the usual representations with those specified
19952040
if callable(rep_mapping):
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rep = rep_mapping(x)
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# avoid hashing entries, especially algebraic numbers
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elif rep_mapping and x in rep_mapping:
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rep = rep_mapping.get(x)
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elif fmt_numeric is not None:
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rep = fmt_numeric.format(x, prec=prec)
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else:
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rep = repr(x)
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S.append(rep)

‎src/sage/repl/display/formatter.py

+39
Original file line numberDiff line numberDiff line change
@@ -104,6 +104,10 @@ def __init__(self, *args, **kwds):
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from sage.repl.rich_output.backend_ipython import BackendIPython
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self.dm.check_backend_class(BackendIPython)
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pt_formatter = self.formatters[PLAIN_TEXT]
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pt_formatter.observe(self._ipython_float_precision_changed,
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names=['float_precision'])
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def format(self, obj, include=None, exclude=None):
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r"""
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Use the Sage rich output instead of IPython
@@ -195,6 +199,41 @@ def format(self, obj, include=None, exclude=None):
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ipy_metadata[PLAIN_TEXT] = sage_metadata[PLAIN_TEXT]
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return ipy_format, ipy_metadata
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@staticmethod
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def _ipython_float_precision_changed(change):
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"""
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Update the current float precision for the display of matrices in Sage.
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This function is called when the IPython ``%precision`` magic is
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invoked.
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TESTS::
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sage: from sage.repl.interpreter import get_test_shell
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sage: shell = get_test_shell()
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sage: shell.run_cell('%precision 4')
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'%.4f'
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sage: shell.run_cell('matrix.options.precision') # indirect doctest
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4
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sage: shell.run_cell('%precision')
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'%r'
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sage: shell.run_cell('matrix.options.precision') # indirect doctest
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None
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"""
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from sage.matrix.constructor import options
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s = change.new
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if not s:
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# unset the precision
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options.precision = None
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else:
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try:
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prec = int(s)
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if prec >= 0:
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options.precision = prec
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# otherwise ignore the change
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except ValueError:
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pass
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class SagePlainTextFormatter(PlainTextFormatter):
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