Plotting utilities

sage.plot.misc.get_matplotlib_linestyle(linestyle, return_type)

Function which translates between matplotlib linestyle in short notation (i.e. ‘-‘, ‘–’, ‘:’, ‘-.’) and long notation (i.e. ‘solid’, ‘dashed’, ‘dotted’, ‘dashdot’ ).

If linestyle is none of these allowed options, the function raises a ValueError.

INPUT:

  • linestyle - The style of the line, which is one of

    • "-" or "solid"

    • "--" or "dashed"

    • "-." or "dash dot"

    • ":" or "dotted"

    • "None" or " " or "" (nothing)

    The linestyle can also be prefixed with a drawing style (e.g., "steps--")

    • "default" (connect the points with straight lines)

    • "steps" or "steps-pre" (step function; horizontal line is to the left of point)

    • "steps-mid" (step function; points are in the middle of horizontal lines)

    • "steps-post" (step function; horizontal line is to the right of point)

    If linestyle is None (of type NoneType), then we return it back unmodified.

  • return_type - The type of linestyle that should be output. This argument takes only two values - "long" or "short".

EXAMPLES:

Here is an example how to call this function:

sage: from sage.plot.misc import get_matplotlib_linestyle
sage: get_matplotlib_linestyle(':', return_type='short')
':'

sage: get_matplotlib_linestyle(':', return_type='long')
'dotted'
sage.plot.misc.setup_for_eval_on_grid(funcs, ranges, plot_points=None, return_vars=False)

Calculate the necessary parameters to construct a list of points, and make the functions fast_callable.

INPUT:

  • funcs – a function, or a list, tuple, or vector of functions

  • ranges – a list of ranges. A range can be a 2-tuple of numbers specifying the minimum and maximum, or a 3-tuple giving the variable explicitly.

  • plot_points – a tuple of integers specifying the number of plot points for each range. If a single number is specified, it will be the value for all ranges. This defaults to 2.

  • return_vars – (default False) If True, return the variables, in order.

OUTPUT:

  • fast_funcs - if only one function passed, then a fast callable function. If funcs is a list or tuple, then a tuple of fast callable functions is returned.

  • range_specs - a list of range_specs: for each range, a tuple is returned of the form (range_min, range_max, range_step) such that srange(range_min, range_max, range_step, include_endpoint=True) gives the correct points for evaluation.

EXAMPLES:

sage: x,y,z=var('x,y,z')
sage: f(x,y)=x+y-z
sage: g(x,y)=x+y
sage: h(y)=-y
sage: sage.plot.misc.setup_for_eval_on_grid(f, [(0, 2),(1,3),(-4,1)], plot_points=5)
(<sage.ext...>, [(0.0, 2.0, 0.5), (1.0, 3.0, 0.5), (-4.0, 1.0, 1.25)])
sage: sage.plot.misc.setup_for_eval_on_grid([g,h], [(0, 2),(-1,1)], plot_points=5)
((<sage.ext...>, <sage.ext...>), [(0.0, 2.0, 0.5), (-1.0, 1.0, 0.5)])
sage: sage.plot.misc.setup_for_eval_on_grid([sin,cos], [(-1,1)], plot_points=9)
((<sage.ext...>, <sage.ext...>), [(-1.0, 1.0, 0.25)])
sage: sage.plot.misc.setup_for_eval_on_grid([lambda x: x^2,cos], [(-1,1)], plot_points=9)
((<function <lambda> ...>, <sage.ext...>), [(-1.0, 1.0, 0.25)])
sage: sage.plot.misc.setup_for_eval_on_grid([x+y], [(x,-1,1),(y,-2,2)])
((<sage.ext...>,), [(-1.0, 1.0, 2.0), (-2.0, 2.0, 4.0)])
sage: sage.plot.misc.setup_for_eval_on_grid(x+y, [(x,-1,1),(y,-1,1)], plot_points=[4,9])
(<sage.ext...>, [(-1.0, 1.0, 0.6666666666666666), (-1.0, 1.0, 0.25)])
sage: sage.plot.misc.setup_for_eval_on_grid(x+y, [(x,-1,1),(y,-1,1)], plot_points=[4,9,10])
Traceback (most recent call last):
...
ValueError: plot_points must be either an integer or a list of integers, one for each range
sage: sage.plot.misc.setup_for_eval_on_grid(x+y, [(1,-1),(y,-1,1)], plot_points=[4,9,10])
Traceback (most recent call last):
...
ValueError: Some variable ranges specify variables while others do not

Beware typos: a comma which should be a period, for instance:

sage: sage.plot.misc.setup_for_eval_on_grid(x+y, [(x, 1, 2), (y, 0,1, 0.2)], plot_points=[4,9,10])
Traceback (most recent call last):
...
ValueError: At least one variable range has more than 3 entries: each should either have 2 or 3 entries, with one of the forms (xmin, xmax) or (x, xmin, xmax)

sage: sage.plot.misc.setup_for_eval_on_grid(x+y, [(y,1,-1),(x,-1,1)], plot_points=5)
(<sage.ext...>, [(1.0, -1.0, 0.5), (-1.0, 1.0, 0.5)])
sage: sage.plot.misc.setup_for_eval_on_grid(x+y, [(x,1,-1),(x,-1,1)], plot_points=5)
Traceback (most recent call last):
...
ValueError: range variables should be distinct, but there are duplicates
sage: sage.plot.misc.setup_for_eval_on_grid(x+y, [(x,1,1),(y,-1,1)])
Traceback (most recent call last):
...
ValueError: plot start point and end point must be different
sage: sage.plot.misc.setup_for_eval_on_grid(x+y, [(x,1,-1),(y,-1,1)], return_vars=True)
(<sage.ext...>, [(1.0, -1.0, 2.0), (-1.0, 1.0, 2.0)], [x, y])
sage: sage.plot.misc.setup_for_eval_on_grid(x+y, [(y,1,-1),(x,-1,1)], return_vars=True)
(<sage.ext...>, [(1.0, -1.0, 2.0), (-1.0, 1.0, 2.0)], [y, x])
sage.plot.misc.unify_arguments(funcs)

Return a tuple of variables of the functions, as well as the number of “free” variables (i.e., variables that defined in a callable function).

INPUT:

  • funcs – a list of functions; these can be symbolic expressions, polynomials, etc

OUTPUT: functions, expected arguments

  • A tuple of variables in the functions

  • A tuple of variables that were “free” in the functions

EXAMPLES:

sage: x,y,z=var('x,y,z')
sage: f(x,y)=x+y-z
sage: g(x,y)=x+y
sage: h(y)=-y
sage: sage.plot.misc.unify_arguments((f,g,h))
((x, y, z), (z,))
sage: sage.plot.misc.unify_arguments((g,h))
((x, y), ())
sage: sage.plot.misc.unify_arguments((f,z))
((x, y, z), (z,))
sage: sage.plot.misc.unify_arguments((h,z))
((y, z), (z,))
sage: sage.plot.misc.unify_arguments((x+y,x-y))
((x, y), (x, y))