#!/usr/bin/env python # -*- coding: utf-8 -*- # Copyright 1999-2020 Alibaba Group Holding Ltd. # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. from ..datasource import tensor as astensor from .ravel import ravel [docs]def ediff1d(a, to_end=None, to_begin=None): """ The differences between consecutive elements of a tensor. Parameters ---------- a : array_like If necessary, will be flattened before the differences are taken. to_end : array_like, optional Number(s) to append at the end of the returned differences. to_begin : array_like, optional Number(s) to prepend at the beginning of the returned differences. Returns ------- ediff1d : Tensor The differences. Loosely, this is ``a.flat[1:] - a.flat[:-1]``. See Also -------- diff, gradient Examples -------- >>> import mars.tensor as mt >>> x = mt.array([1, 2, 4, 7, 0]) >>> mt.ediff1d(x).execute() array([ 1, 2, 3, -7]) >>> mt.ediff1d(x, to_begin=-99, to_end=mt.array([88, 99])).execute() array([-99, 1, 2, 3, -7, 88, 99]) The returned tensor is always 1D. >>> y = [[1, 2, 4], [1, 6, 24]] >>> mt.ediff1d(y).execute() array([ 1, 2, -3, 5, 18]) """ from ..merge import concatenate a = astensor(a) a = ravel(a) t = a[1:] - a[:-1] if to_begin is None and to_end is None: return t to_concat = [t] if to_begin is not None: to_concat.insert(0, ravel(astensor(to_begin))) if to_end is not None: to_concat.append(ravel(astensor(to_end))) return concatenate(to_concat)