python - Sci-kit 学习如何打印混淆矩阵的标签？

问题描述

所以我正在使用 sci-kit learn 对一些数据进行分类。我有 13 个不同的类值/分类来对数据进行分类。现在我已经能够使用交叉验证并打印混淆矩阵了。但是，它只显示没有类标签的 TP 和 FP 等，所以我不知道哪个类是什么。下面是我的代码和我的输出：

def classify_data(df, feature_cols, file):
    nbr_folds = 5
    RANDOM_STATE = 0
    attributes = df.loc[:, feature_cols]  # Also known as x
    class_label = df['task']  # Class label, also known as y.
    file.write("\nFeatures used: ")
    for feature in feature_cols:
        file.write(feature + ",")
    print("Features used", feature_cols)

    sampler = RandomOverSampler(random_state=RANDOM_STATE)
    print("RandomForest")
    file.write("\nRandomForest")
    rfc = RandomForestClassifier(max_depth=2, random_state=RANDOM_STATE)
    pipeline = make_pipeline(sampler, rfc)
    class_label_predicted = cross_val_predict(pipeline, attributes, class_label, cv=nbr_folds)
    conf_mat = confusion_matrix(class_label, class_label_predicted)
    print(conf_mat)
    accuracy = accuracy_score(class_label, class_label_predicted)
    print("Rows classified: " + str(len(class_label_predicted)))
    print("Accuracy: {0:.3f}%\n".format(accuracy * 100))
    file.write("\nClassifier settings:" + str(pipeline) + "\n")
    file.write("\nRows classified: " + str(len(class_label_predicted)))
    file.write("\nAccuracy: {0:.3f}%\n".format(accuracy * 100))
    file.writelines('\t'.join(str(j) for j in i) + '\n' for i in conf_mat)

#Output
Rows classified: 23504
Accuracy: 17.925%
0   372 46  88  5   73  0   536 44  317 0   200 127
0   501 29  85  0   136 0   655 9   154 0   172 67
0   97  141 78  1   56  0   336 37  429 0   435 198
0   135 74  416 5   37  0   507 19  323 0   128 164
0   247 72  145 12  64  0   424 21  296 0   304 223
0   190 41  36  0   178 0   984 29  196 0   111 43
0   218 13  71  7   52  0   917 139 177 0   111 103
0   215 30  84  3   71  0   1175    11  55  0   102 62
0   257 55  156 1   13  0   322 184 463 0   197 160
0   188 36  104 2   34  0   313 99  827 0   69  136
0   281 80  111 22  16  0   494 19  261 0   313 211
0   207 66  87  18  58  0   489 23  157 0   464 239
0   113 114 44  6   51  0   389 30  408 0   338 315

如您所见，您无法真正知道哪一列是什么，并且打印也“未对齐”，因此很难理解。

有没有办法打印标签？

标签： pythonmachine-learningscikit-learnconfusion-matrix

从doc看来，似乎没有打印混淆矩阵的行和列标签的选项。但是，您可以使用参数指定标签顺序labels=...

例子：

from sklearn.metrics import confusion_matrix

y_true = ['yes','yes','yes','no','no','no']
y_pred = ['yes','no','no','no','no','no']
print(confusion_matrix(y_true, y_pred))
# Output:
# [[3 0]
#  [2 1]]
print(confusion_matrix(y_true, y_pred, labels=['yes', 'no']))
# Output:
# [[1 2]
#  [0 3]]

如果要打印带有标签的混淆矩阵，可以尝试pandas设置.indexcolumnsDataFrame

import pandas as pd
cmtx = pd.DataFrame(
    confusion_matrix(y_true, y_pred, labels=['yes', 'no']), 
    index=['true:yes', 'true:no'], 
    columns=['pred:yes', 'pred:no']
)
print(cmtx)
# Output:
#           pred:yes  pred:no
# true:yes         1        2
# true:no          0        3

或者

unique_label = np.unique([y_true, y_pred])
cmtx = pd.DataFrame(
    confusion_matrix(y_true, y_pred, labels=unique_label), 
    index=['true:{:}'.format(x) for x in unique_label], 
    columns=['pred:{:}'.format(x) for x in unique_label]
)
print(cmtx)
# Output:
#           pred:no  pred:yes
# true:no         3         0
# true:yes        2         1

python - Sci-kit 学习如何打印混淆矩阵的标签？

问题描述

解决方案

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