Example usage of Coordinate Encoder

Engineering NuPIC
6

According to documentation, you need not assume a fixed 3-dimensional space, so XY should be totally reasonable. Regardless of dimensionality, you do need to specify a radius, which GeoSpatialCoordinateEncoder maps “speed” onto. GeoSpatialCoordinateEncoder is a subclass of CoordinateEncoder and is designed to work with latlong data.

I’m confused, however, in trying to put together a quick-and-dirty example and am running into what appears to be a bug. For example, this code snippet:

from nupic.encoders import CoordinateEncoder
import numpy

coords = numpy.array([1.0, 2.0, 3.0])
radius = 3.0
enc = CoordinateEncoder()
enc.encode((coords, radius))

Produces this error:

Traceback (most recent call last):
  File "coord.py", line 7, in <module>
    enc.encode((coords, radius))
  File "/Users/amarshall/nta/nupic/src/nupic/encoders/base.py", line 133, in encode
    self.encodeIntoArray(inputData, output)
  File "/Users/amarshall/nta/nupic/src/nupic/encoders/coordinate.py", line 109, in encodeIntoArray
    neighbors = self._neighbors(coordinate, radius)
  File "/Users/amarshall/nta/nupic/src/nupic/encoders/coordinate.py", line 130, in _neighbors
    ranges = [range(n-radius, n+radius+1) for n in coordinate.tolist()]
TypeError: range() integer end argument expected, got float.

Casting radius to int doesn’t help, either because of this detail in the implementation of CoordinateEncoder._neighbors():

ranges = [range(n-radius, n+radius+1) for n in coordinate.tolist()]

i.e. coordinates are floats, so n+radius+1 results in a float, which is an invalid value for the second argument to range().

Sticking to int works (see below), but that requirement is inconsistent with the documentation and (I think) most people’s expectations.

These [1-3]-dimensional one-liner examples work fine:

print CoordinateEncoder().encode((numpy.array([1]), 3))
print CoordinateEncoder().encode((numpy.array([1, 2]), 3))
print CoordinateEncoder().encode((numpy.array([1, 2, 3]), 3))

Expect a proper github issue/bug report to follow.

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