Question

我将以下MATLAB代码转换为Python：

function segments = segmentSlidingWindow(data, wSize, sSize)
    len = size(data,1);
    wCurr = 1;
    segments = []; % todo: init to make faster
    while (wCurr<len-wSize)
        segments = [segments; wCurr wCurr+wSize]; % start stop
        wCurr = wCurr+sSize; % step forward
    end
    segments = [segments; wCurr len]; % add residual
end

我在Numpy for Matlab users guide

之后编写了以下Python代码

def sliding_window(data, window_size, step_size):
    length = data.shape[0]
    wCurr = 0
    segments = []
    while wCurr < length - window_size:
        segments = np.vstack([np.hstack([segments]), np.hstack([wCurr, window_size + wCurr])])
        wCurr = wCurr + step_size
    segments = np.vstack([np.hstack([segments]), np.hstack([wCurr, length])])
    plt.plot(segments)
    plt.show()
    return segments

我还会绘制分段数据以查看其外观。但是，我不能运行这个Python代码，因为在线：

segments = np.vstack([np.hstack([segments]), np.hstack([wCurr, window_size + wCurr])])

我收到以下错误：

ValueError: all the input array dimensions except for the concatenation axis must match exactly

当我打印length时，我得到504

我的数据是一个包含5列的pandas DataFrame。我只想在中间三列上有一个滑动窗口，因为它们是唯一相关的。第一列是时间戳，最后一列是标签。

wSize和sSize是整数。

我想为这样的事情制作一个滑动窗口：

 1495573445.162, 0, 0.021973, 0.012283, -0.995468, 1
 1495573445.172, 0, 0.021072, 0.013779, -0.994308, 1
 1495573445.182, 0, 0.020157, 0.015717, -0.995575, 1
 1495573445.192, 0, 0.017883, 0.012756, -0.993927, 1
 1495573445.202, 0, 0.021194, 0.012161, -0.994705, 1
 1495573445.212, 0, 0.019638, 0.013718, -0.994019, 1
 1495573445.222, 0, 0.019440, 0.010803, -0.994476, 1
 1495573445.232, 0, 0.018112, 0.010849, -0.993073, 1
 1495573445.242, 0, 0.020157, 0.011154, -0.994644, 1
 1495573445.252, 0, 0.020340, 0.010040, -0.995804, 1
 1495573445.262, 0, 0.017792, 0.009857, -0.996078, 1
 1495573445.272, 0, 0.020538, 0.010239, -0.994858, 1

其中输出为滚动窗口，步长为窗口大小的一半。

Answer 1

我有一种感觉，你很可能想用这样的东西替换你的while循环：

s = np.arange(0, length - window_size, step_size)
segments = np.vstack([s, s + window_size]).T

length = 15; step_size = 3; window_size = 6;段的内容如下：

array([[ 0, 6],
       [ 3, 9],
       [ 6, 12]])

如果您想要转置的答案，请在上述代码中的.T后删除vstack，获取：

array([[ 0,  3,  6],
       [ 6,  9, 12]])

如果你真的坚持使用while循环，那么：

segments = np.empty((0, 2), dtype=np.int)
while wCurr < length - window_size:
    segments = np.vstack([segments, [wCurr, window_size + wCurr]])
    wCurr = wCurr + step_size

或：

segments = np.empty((0, 2), dtype=np.int)
while wCurr < length - window_size:
    segments = np.append(segments, [[wCurr, window_size + wCurr]], axis=0)
    wCurr = wCurr + step_size

创建不同大小的hstack的Python np vstack

1 个答案: