python - scikit multilearn:accuracy_score ValueError:不支持多类多输出
问题描述
我想预测一次可以包含多个标签的样本(多标签分类)。所以我使用了scikit-multilearn库并成功拟合了一个分类器,甚至可以预测测试数据。它只是无法输出分类器的准确性。
我的数据(最多 1100 行):
依赖变量(我预测的变量)是最后 4 个:N/xN、Sex、Maturity和CType。其余的是独立变量。
我所说的准确度是分类器与预测所有标签的接近程度。
这是代码:
import numpy as np
import pandas as pd
from scipy import sparse
from sklearn.metrics import accuracy_score
from sklearn.model_selection import train_test_split
from sklearn.svm import SVC
from skmultilearn.problem_transform import BinaryRelevance
# Prepare data
df = pd.read_csv("Data_Numeric.csv")
# remove crab_id for now
del df['Crab_id']
# independent vars: the rest
# dependent vars: N/xN, Gender, Maturity, CType
# n_samples = 1100
# n_features = 6
# n_labels = 4
X = df.iloc[:, :6].values
y = df.iloc[:, 6:df.shape[1]].astype(np.int64).values
X = sparse.csr_matrix(X)
y = sparse.csr_matrix(y, dtype=np.int64)
X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.3)
# generate model
classifier = BinaryRelevance(SVC())
# train
classifier.fit(X_train, y_train)
# predict
y_pred = classifier.predict(X_test)
y_pred_array = y_pred.toarray()
# my_data = X_test[0:4, :]
# my_data[0] = [64.7, 46, 12, 13, 0, 0]
# my_data_prediction = classifier.predict(my_data).toarray()
# my_data_true = y_test[0:4, :].toarray()
# error here
score = accuracy_score(y_test.toarray(), y_pred.toarray())
错误是
Traceback (most recent call last):
File "<input>", line 42, in <module>
File "/home/f4ww4z/anaconda3/envs/ayah/lib/python3.7/site-packages/sklearn/metrics/_classification.py", line 185, in accuracy_score
y_type, y_true, y_pred = _check_targets(y_true, y_pred)
File "/home/f4ww4z/anaconda3/envs/ayah/lib/python3.7/site-packages/sklearn/metrics/_classification.py", line 97, in _check_targets
raise ValueError("{0} is not supported".format(y_type))
ValueError: multiclass-multioutput is not supported
y_test
>>> y_test
<330x4 sparse matrix of type '<class 'numpy.longlong'>'
with 578 stored elements in Compressed Sparse Row format>
y_test.toarray()
,形状为330x4
:
y_pred
>>> y_pred
<330x4 sparse matrix of type '<class 'numpy.longlong'>'
with 408 stored elements in Compressed Sparse Column format>
y_pred.toarray()
:
如何正确查看分类器的准确性?
解决方案
from sklearn.model_selection import cross_validate, KFold
clf = BinaryRelevance(SVC())
k_fold = KFold(n_splits=5, shuffle=True, random_state=42)
scores = cross_validate(clf, X_train, y_train, cv=k_fold, scoring=['accuracy'])
或者
scores = cross_val_score(clf, X_train, y_train, cv=5)
通过使用交叉验证方法,您可以获得 5 个准确度分数,然后取它们的平均值。
您可以使用 MultioutputClassifier 和 RandomForestClassifier 进行基本操作
from sklearn.ensemble import RandomForestClassifier
from sklearn.model_selection import cross_validate, KFold
from sklearn.multioutput import MultiOutputClassifier
clf=MultiOutputClassifier(RandomForestClassifier(random_state=42,class_weight="balanced"))
k_fold = KFold(n_splits=5, shuffle=True, random_state=42)
scores = cross_validate(clf, X_train_tf, y_train, cv=k_fold, scoring=['f1_weighted'])
也许这会对你有所帮助:)
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