python - 如何在不使用循环的情况下重写 NumPy 代码

Question

我有代码应该找出生成的 NumPy 数组中的极值并将它们一一写在一个新数组中(最小值、最大值、最小值、最大值等)这段代码可以工作，但是速度太慢。所以我需要在没有循环的情况下完成它。我已经用 numpy.logic_and 删除了一个，但剩下的两个是大的。也许 np.where 可以工作，但我不知道如何在这里使用它们。

代码

import numpy as np
from scipy.signal import argrelextrema
import matplotlib.pyplot as plt
import timeit


if __name__ == '__main__':
    N = 1000000  # Length of an array
    T = 4  # Diff between indexes of an array
    D = 4  # Diff between values of an array
    x = np.random.uniform(low=-1, high=1, size=N)
    x[0] = 1  # Starting value
    x = np.cumsum(x)  # Using cumsum for faster generating
    index = []  # Array for indexes of local extremums
    mins = argrelextrema(x, np.less)[0]  # Array of min local extremums
    maxs = argrelextrema(x, np.greater)[0]  # Array of max local extremums
    # print('AutoGenerated NumPy massive prepared using np.cumsum() \n', x)
    index.append(mins[0])  # Zero will be min
    min_elem = mins[0]
    assert index[0] in mins
    for max_elem in maxs:
        # Checking the diff in values and in indexes, write if if suites
        if x[max_elem] - x[min_elem] >= D and max_elem - min_elem >= T:
            # Check if there's more suitable local minimum
            min_elem = np.argmin(x[min_elem:max_elem]) + min_elem
            index[-1] = min_elem
            index.append(max_elem)
            assert index[-1] in maxs
            assert max_elem - min_elem >= T
            assert x[max_elem] - x[min_elem] >= D
            assert np.all(np.logical_and(x[min_elem+1:max_elem] >= x[min_elem],
                                         x[min_elem+1:max_elem] <= x[max_elem]))
            for min_elem in mins:
                # Checking the diff in values and in indexes, write if if suites
                if x[max_elem] - x[min_elem] >= D and min_elem - max_elem >= T:
                    # Check if there's more suitable local maximum
                    max_elem = np.argmax(x[max_elem:min_elem]) + max_elem
                    index[-1] = max_elem
                    index.append(min_elem)
                    assert index[-1] in mins
                    assert min_elem - max_elem >= T
                    assert x[max_elem] - x[min_elem] >= D
                    break

Answer 1

建议:

编辑:

• 在测试代码之前删除所有不需要的“打印”语句，如 Console Output速度很慢并且会给你错误的计时。

• 已添加错误消息至 assert statements例如 assert x >= 0, 'x 小于零'

• 尝试消除 y 中的 x 语句，因为语言/编译器必须检查 y 中的每个元素以查看是否 x 存在。 References

祝你好运。