90 lines
3.2 KiB
Python
90 lines
3.2 KiB
Python
from ._mcp import MCP, MCP_Geometric, MCP_Connect, MCP_Flexible
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def route_through_array(array, start, end, fully_connected=True,
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geometric=True):
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"""Simple example of how to use the MCP and MCP_Geometric classes.
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See the MCP and MCP_Geometric class documentation for explanation of the
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path-finding algorithm.
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Parameters
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----------
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array : ndarray
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Array of costs.
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start : iterable
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n-d index into `array` defining the starting point
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end : iterable
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n-d index into `array` defining the end point
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fully_connected : bool (optional)
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If True, diagonal moves are permitted, if False, only axial moves.
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geometric : bool (optional)
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If True, the MCP_Geometric class is used to calculate costs, if False,
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the MCP base class is used. See the class documentation for
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an explanation of the differences between MCP and MCP_Geometric.
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Returns
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-------
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path : list
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List of n-d index tuples defining the path from `start` to `end`.
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cost : float
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Cost of the path. If `geometric` is False, the cost of the path is
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the sum of the values of `array` along the path. If `geometric` is
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True, a finer computation is made (see the documentation of the
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MCP_Geometric class).
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See Also
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--------
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MCP, MCP_Geometric
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Examples
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--------
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>>> import numpy as np
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>>> from skimage.graph import route_through_array
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>>>
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>>> image = np.array([[1, 3], [10, 12]])
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>>> image
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array([[ 1, 3],
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[10, 12]])
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>>> # Forbid diagonal steps
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>>> route_through_array(image, [0, 0], [1, 1], fully_connected=False)
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([(0, 0), (0, 1), (1, 1)], 9.5)
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>>> # Now allow diagonal steps: the path goes directly from start to end
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>>> route_through_array(image, [0, 0], [1, 1])
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([(0, 0), (1, 1)], 9.19238815542512)
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>>> # Cost is the sum of array values along the path (16 = 1 + 3 + 12)
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>>> route_through_array(image, [0, 0], [1, 1], fully_connected=False,
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... geometric=False)
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([(0, 0), (0, 1), (1, 1)], 16.0)
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>>> # Larger array where we display the path that is selected
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>>> image = np.arange((36)).reshape((6, 6))
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>>> image
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array([[ 0, 1, 2, 3, 4, 5],
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[ 6, 7, 8, 9, 10, 11],
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[12, 13, 14, 15, 16, 17],
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[18, 19, 20, 21, 22, 23],
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[24, 25, 26, 27, 28, 29],
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[30, 31, 32, 33, 34, 35]])
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>>> # Find the path with lowest cost
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>>> indices, weight = route_through_array(image, (0, 0), (5, 5))
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>>> indices = np.stack(indices, axis=-1)
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>>> path = np.zeros_like(image)
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>>> path[indices[0], indices[1]] = 1
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>>> path
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array([[1, 1, 1, 1, 1, 0],
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[0, 0, 0, 0, 0, 1],
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[0, 0, 0, 0, 0, 1],
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[0, 0, 0, 0, 0, 1],
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[0, 0, 0, 0, 0, 1],
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[0, 0, 0, 0, 0, 1]])
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"""
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start, end = tuple(start), tuple(end)
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if geometric:
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mcp_class = MCP_Geometric
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else:
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mcp_class = MCP
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m = mcp_class(array, fully_connected=fully_connected)
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costs, traceback_array = m.find_costs([start], [end])
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return m.traceback(end), costs[end]
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