"""

plot

~~~~

Utility methods for interacting with matplotlib

"""

import matplotlib.patches

from . import data as _data

try:

import descartes

except:

import sys

print("Failed to load 'descartes' package.", file=sys.stderr)

descartes = None

try:

import shapely.geometry as _sgeometry

except:

import sys

print("Failed to load 'shapely' package.", file=sys.stderr)

_sgeometry = None

def outline_of_grid(grid):

"""Returns a `shapely` (multi-)polygon object given by merging all the

grid cells from the passed :class:`MaskedGrid` object.

:param grid: A :class:`MaskedGrid` instace.

:return: A `shapely` geometry object.

"""

height, width = grid.mask.shape

polygon = None

for y in range(height):

yy = y * grid.ysize + grid.yoffset

for x in range(width):

if grid.is_valid(x, y):

xx = x * grid.xsize + grid.xoffset

poly = _sgeometry.Polygon([[xx,yy], [xx+grid.xsize, yy],

[xx+grid.xsize, yy+grid.ysize], [xx, yy+grid.ysize]])

if polygon is None:

polygon = poly

else:

polygon = polygon.union(poly)

return polygon

def patches_from_grid(grid):

"""Returns a list of `matplotlib` `patches` from the passed

:class:`MaskedGrid` object. Typical usage:

pc = matplotlib.collections.PatchCollection(patches_from_grid(grid))

fig, ax = plt.subplots()

ax.add_collection(pc)

This will be slow if there are a large number of grid cells.

:param grid: A :class:`MaskedGrid` instace.

:return: A list of patches.

"""

height, width = grid.mask.shape

patches = []

for y in range(height):

yy = y * grid.ysize + grid.yoffset

for x in range(width):

if grid.is_valid(x, y):

xx = x * grid.xsize + grid.xoffset

patches.append(matplotlib.patches.Rectangle((xx, yy), grid.xsize, grid.ysize))

return patches

def _add_line(lines, x1, y1, x2, y2):

lines.append([(x1,y1), (x2,y2)])

def lines_from_grid(grid):

"""Returns a list of line segments which when drawn will form the cells of

the passed :class:`MaskedGrid` object. Typical usage:

lc = matplotlib.collections.LineCollection(lines_from_grid(grid))

fig, ax = plt.subplots()

ax.add_collection(lc)

This is somewhat quicker than using :func:`patches_from_grid` but still

slow.

:param grid: A :class:`MaskedGrid` instace.

:return: A list of "line"s. Each line is a list with two entries, each

entry being a tuple `(x,y)` of coordinates.

This is somewhat quicker than using

"""

height, width = grid.mask.shape

lines = []

for y in range(height):

yy = y * grid.ysize + grid.yoffset

for x in range(width):

if grid.is_valid(x, y):

xx = x * grid.xsize + grid.xoffset

xx1 = xx + grid.xsize

yy1 = yy + grid.ysize

_add_line(lines, xx, yy, xx1, yy)

_add_line(lines, xx, yy, xx, yy1)

_add_line(lines, xx1, yy, xx1, yy1)

_add_line(lines, xx, yy1, xx1, yy1)

return lines

def lines_from_regular_grid(grid):

"""As :func:`lines_from_grid` but the passed grid is assumed to be a whole

rectangle, not a more complicated masked object. Hugely faster.

"""

height, width = grid.mask.shape

lines = []

for y in range(height+1):

yy0 = y * grid.ysize + grid.yoffset

xx0 = grid.xoffset

xx1 = xx0 + width * grid.xsize

_add_line(lines, xx0,yy0, xx1,yy0)

for x in range(width+1):

xx0 = x * grid.xsize + grid.xoffset

yy0 = grid.yoffset

yy1 = yy0 + height * grid.ysize

_add_line(lines, xx0,yy0, xx0,yy1)

return lines

def patches_from_geometry(geo, **kwargs):

"""Convert an iterable of geometry to `matplotlib` patches.

:param geo: An iterable of geometry items. If `descartes` cannot parse

an item, it is ignored.

:param **kwargs: Any key-word arguments to forward on to the `patch`

constructor.

:return: A list of `matplotlib.patches.Patch` objects.

"""

patches = []

for x in geo:

try:

patches.append(descartes.PolygonPatch(x, **kwargs))

except:

pass

return patches

def lines_from_geometry(geo):

"""Convert an iterable of geometry to lines. Suitable for passing

directly to `matplotlib.collections.LineCollection`.

:param geo: An iterable of geometry items. If cannot be coverted to a

line, then ignored.

:return: A list of coordinates.

"""

lines = []

for x in geo:

try:

lines.append( list(x.coords) )

except:

pass

return lines