如何使用子圖制作單個圖例？_get_legend_handles_labels不起作用

我想打一個單一的傳說與相應的顏色是在對整個次要情節的個別地塊的車型。

我目前的代碼如下：

from matplotlib.legend import _get_legend_handles_labels

colors = ['red', 'blue','darkblue', 'purple', 'orange', 'brown', 'pink', 'darkgreen', 'gray']
models = ['Logistic Regression', 'SVM', 'Decision Tree', 'Random Forest', 'XGBoost', 'ADABoost', 'Gaussian NB', 'KNN', 'MLP']

# English

fig, axs = plt.subplots(4,2, figsize=(25,15))
fig.suptitle('Performance measures for English and Arabic data', fontsize = 25)

axs[0,0].bar(models, en_f1_scores, color=colors)
axs[0,0].set_title("English F1 score", fontsize = 20)

axs[1,0].bar(models, en_acc_scores, color=colors)
axs[1,0].set_title("English accuracy score", fontsize = 20)

axs[2,0].bar(models, en_recall_scores, color=colors)
axs[2,0].set_title("English recall score", fontsize = 20)

axs[3,0].bar(models, en_precision_scores, color=colors)
axs[3,0].set_title("English precision score", fontsize = 20)

# Arabic

axs[0,1].bar(models, ar_f1_scores, color=colors)
axs[0, 1].set_title("Arabic F1 score", fontsize = 20)

axs[1,1].bar(models, ar_accuracy_scores, color=colors)
axs[1,1].set_title("Arabic accuracy score", fontsize = 20)

axs[2,1].bar(models, ar_recall_scores, color=colors)
axs[2,1].set_title("Arabic recall score", fontsize = 20)

axs[3,1].bar(models, ar_precision_scores, color=colors)
axs[3,1].set_title("Arabic precision score", fontsize = 20)

fig.tight_layout(pad=3.0)

當前輸出如下所示：

添加此代碼：

lines, labels = fig.axes[-1].get_legend_handles_labels()
fig.legend(lines, labels, loc = 'upper center')

什么都不做，它顯示給我的是：

<matplotlib.legend.Legend 在 0x266574402b0>

此外，行和標簽都是空陣列；[]

我該怎么做才能在子圖的頂部添加圖例？（如果是橫向傳說就更好了！）

謝謝！

uj5u.com熱心網友回復：

首先，我建議將所有資訊保存到串列中，這樣可以通過一個大回圈來繪制繪圖。這樣，如果某些細節發生變化，只需在一個地方進行更改。

要創建圖例，將自動添加具有“標簽”的圖形元素。通常，完整的條形圖只有一個標簽。通過深入生成的條形，可以分配單獨的標簽。

該代碼首先創建一個虛擬圖例，因此fig.tight_layout()可以調整所有間距并為圖例留出一些位置。呼叫后fig.tight_layout()，真正的圖例就被創建了。（對于真正的圖例，fig.tight_layout()會嘗試將其完全分配給一個子圖，并在兩列子圖之間產生很大的差距）。

import matplotlib.pyplot as plt
import numpy as np

colors = ['red', 'blue', 'darkblue', 'purple', 'orange', 'brown', 'pink', 'darkgreen', 'gray']
models = ['Logistic Regression', 'SVM', 'Decision Tree', 'Random Forest', 'XGBoost', 'ADABoost', 'Gaussian NB', 'KNN', 'MLP']

titles = ["F1 score", "accuracy score", "recall score", "precision score"]

N = len(models)
en_f1_scores = np.random.rand(N)
en_acc_scores = np.random.rand(N)
en_recall_scores = np.random.rand(N)
en_precision_scores = np.random.rand(N)
en_scores = [en_f1_scores, en_acc_scores, en_recall_scores, en_precision_scores]
ar_f1_scores = np.random.rand(N)
ar_acc_scores = np.random.rand(N)
ar_recall_scores = np.random.rand(N)
ar_precision_scores = np.random.rand(N)
ar_scores = [ar_f1_scores, ar_acc_scores, ar_recall_scores, ar_precision_scores]

fig, axs = plt.subplots(4, 2, figsize=(25, 15), sharex=True, sharey='row')
fig.suptitle('Performance measures for English and Arabic data', fontsize=25)

for axs_row, en_score, ar_score, title in zip(axs, en_scores, ar_scores, titles):
    for language, score, ax in zip(['English', 'Arabic'], [en_score, ar_score], axs_row):
        ax.bar(models, score, color=colors)
        ax.set_title(language   ' '   title, fontsize=20)
        ax.set_xticks([])  # remove the x tick and their labels
        ax.grid(axis='y', ls=':', color='black')  # add some gridlines
        ax.set_axisbelow(True)  # gridlines behind the bars
        for spine in ['top', 'right', 'left']:  # remove part of the surrounding box, as it gets busy with the grid lines
            ax.spines[spine].set_visible(False)
        ax.margins(x=0.01)  # less white space left and right

# the legend is created for each graphical element that has a "label"
for bar, model in zip(axs[0, 0].containers[0], models):
    bar.set_label(model)
# first create a dummy legend, so fig.tight_layout() makes enough space
axs[0, 0].legend(handles=axs[0, 0].containers[0][:1],
                 bbox_to_anchor=(0, 1.12), loc='lower left')
fig.tight_layout(pad=3.0)
# now create the real legend; if fig.tight_layout() were called on this,
#  it would create a large empty space between the columns of subplots
#  as it wants the legend to belong to only one of the subplots
axs[0, 0].legend(handles=axs[0, 0].containers[0], ncol=len(models),
                 bbox_to_anchor=(1.03, 1.12), loc='lower center', fontsize=18)
plt.show()

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