path.py 文件源码

def length(self, t0=0, t1=1, error=LENGTH_ERROR, min_depth=LENGTH_MIN_DEPTH):
        """Calculate the length of the path up to a certain position"""
        if t0 == 0 and t1 == 1:
            if self._length_info['bpoints'] == self.bpoints() \
                    and self._length_info['error'] >= error \
                    and self._length_info['min_depth'] >= min_depth:
                return self._length_info['length']

        # using scipy.integrate.quad is quick
        if _quad_available:
            s = quad(lambda tau: abs(self.derivative(tau)), t0, t1,
                            epsabs=error, limit=1000)[0]
        else:
            s = segment_length(self, t0, t1, self.point(t0), self.point(t1),
                               error, min_depth, 0)

        if t0 == 0 and t1 == 1:
            self._length_info['length'] = s
            self._length_info['bpoints'] = self.bpoints()
            self._length_info['error'] = error
            self._length_info['min_depth'] = min_depth
            return self._length_info['length']
        else:
            return s