Matplotlib中的PdfPages保存相同的图形twi

Question

提供的以下代码in the matplotlib documentation创建Hinton图：

def hinton(matrix, max_weight=None, ax=None):
    """Draw Hinton diagram for visualizing a weight matrix."""
    ax = ax if ax is not None else plt.gca()

    if not max_weight:
        max_weight = 2 ** np.ceil(np.log(np.abs(matrix).max()) / np.log(2))

    ax.patch.set_facecolor('gray')
    ax.set_aspect('equal', 'box')
    ax.xaxis.set_major_locator(pl.NullLocator())
    ax.yaxis.set_major_locator(pl.NullLocator())

    for (x, y), w in np.ndenumerate(matrix):
        color = 'white' if w > 0 else 'black'
        size = np.sqrt(np.abs(w) / max_weight)
        rect = pl.Rectangle([x - size / 2, y - size / 2], size, size,
                             facecolor=color, edgecolor=color)
        ax.add_patch(rect)

    ax.autoscale_view()
    ax.invert_yaxis()

我想创建两个Hinton图：一个用于从输入层到隐藏层的权重，另一个用于在我的单层MLP中从隐藏层到输出层的权重。我试过（based on this jupyter notebook）：

W = model_created.layers[0].kernel.get_value(borrow=True)
W = np.squeeze(W)
print("W shape : ", W.shape) # (153, 15)

W_out = model_created.layers[1].kernel.get_value(borrow=True)
W_out = np.squeeze(W_out)
print('W_out shape : ', W_out.shape) # (15, 8)

with PdfPages('hinton_again.pdf') as pdf:
    h1 = hinton(W)
    h2 = hinton(W_out)
    pdf.savefig()

我也尝试过（based on this answer）：

h1 = hinton(W)
h2 = hinton(W_out)

pp = PdfPages('hinton_both.pdf')
pp.savefig(h1)
pp.savefig(h2)
pp.close()

不管怎样，结果都是一样的：W的Hinton图绘制了两次。如何在同一个pdf中包含第一组权重的Hinton图和第二组权重的Hinton图（我也会选择两个单独的pdf，只要我能同时得到两个Hinton图）？你知道吗

Answer 1

pdf.savefig()命令保存当前图形。因为当前只有一个数字，所以它将保存两次。为了得到两个图形，需要创建它们，例如通过plt.figure(1)和plt.figure(2)。你知道吗

with PdfPages('hinton_again.pdf') as pdf:
    plt.figure(1)
    h1 = hinton(W)
    pdf.savefig()
    plt.figure(2)
    h2 = hinton(W_out)
    pdf.savefig()

当然，拯救这两块土地的方法有很多种，另一种可能是

fig, ax = plt.subplots()
hinton(W, ax=ax)

fig2, ax2 = plt.subplots()
hinton(W_out, ax=ax2)

with PdfPages('hinton_again.pdf') as pdf:
   pdf.savefig(fig)
   pdf.savefig(fig2)