branch.py 文件源码

def split(self, nsegments=2, length=None, k=1, s=0):
        """Split the branch into segments"""
        if length is None:
            sublength = self.length / nsegments  # the target length of the segments
        else:
            sublength = float(length)

        # get the data that requires interpolation
        x, y, z, r = self['x'], self['y'], self['z'], self['radius']

        # the cumulative length
        t = numpy.r_[0, numpy.cumsum(((x[:-1] - x[1:]) ** 2 + (y[:-1] - y[1:]) ** 2) ** .5)]

        # create interpolation coefficients
        import scipy.interpolate
        splinecoeffs, u = scipy.interpolate.splprep([x, y, z, r], u=t, k=k, s=s)

        # create new parametrization array. It is supposed to consist of the old lengths
        # plus points that cut the length into the proper segment size
        tnew = t.tolist()
        # the indices where to split the resulting tnew
        indices = [0]
        import bisect
        for n in range(1, int(self.length / sublength) + 1):
            index = bisect.bisect_left(tnew, n * sublength)
            indices.append(index)
            bisect.insort_left(tnew, n * sublength)

        # append the end index for the last segment if last segment size is larger than eps
        if tnew[-1] - tnew[-2] > 0.01:
            indices.append(len(tnew))

        # interpolate the parametrization
        xn, yn, zn, rn = scipy.interpolate.splev(tnew, splinecoeffs)

        branchgen = lambda i0, i1: Branch(x=xn[i0:i1], y=yn[i0:i1], z=zn[i0:i1], r=rn[i0:i1])
        return [branchgen(i0, i1 + 1) for i0, i1 in zip(indices[:-1], indices[1:])]