datasets.fetch_20newsgroups
时间: 2023-11-09 14:08:09 浏览: 46
`datasets.fetch_20newsgroups()`是scikit-learn库中用于获取20个新闻组数据集的函数。这个函数可以从互联网上下载数据集,并将其转换为scikit-learn可以处理的格式。该数据集包含大约20,000个新闻文档,它们属于20个不同的主题(如体育、政治、科技等)。这个数据集通常用于文本分类的任务,例如将新闻文章分为不同的主题类别。
相关问题
请利用lightGBM算法对sklearn.datasets.fetch_20newsgroups的数据进行预测,python代码展示
好的,下面是利用lightGBM算法对sklearn.datasets.fetch_20newsgroups的数据进行预测的Python代码:
首先,我们需要导入所需的库和数据集:
```python
import numpy as np
import pandas as pd
from sklearn.datasets import fetch_20newsgroups
from sklearn.feature_extraction.text import TfidfVectorizer
from sklearn.model_selection import train_test_split
import lightgbm as lgb
# 加载数据集
newsgroups = fetch_20newsgroups(subset='all', remove=('headers', 'footers', 'quotes'))
```
接下来,我们将数据集划分为训练集和测试集,并将文本转换为TF-IDF特征向量:
```python
# 划分训练集和测试集
X_train, X_test, y_train, y_test = train_test_split(newsgroups.data, newsgroups.target, test_size=0.2, random_state=42)
# 将文本转换为TF-IDF特征向量
vectorizer = TfidfVectorizer(stop_words='english')
X_train = vectorizer.fit_transform(X_train)
X_test = vectorizer.transform(X_test)
```
然后,我们可以利用lightGBM算法进行训练和预测:
```python
# 定义lightGBM分类器
lgb_clf = lgb.LGBMClassifier()
# 训练模型
lgb_clf.fit(X_train, y_train)
# 预测测试集
y_pred = lgb_clf.predict(X_test)
# 输出准确率
accuracy = np.mean(y_pred == y_test)
print('Accuracy:', accuracy)
```
完整代码如下:
```python
import numpy as np
import pandas as pd
from sklearn.datasets import fetch_20newsgroups
from sklearn.feature_extraction.text import TfidfVectorizer
from sklearn.model_selection import train_test_split
import lightgbm as lgb
# 加载数据集
newsgroups = fetch_20newsgroups(subset='all', remove=('headers', 'footers', 'quotes'))
# 划分训练集和测试集
X_train, X_test, y_train, y_test = train_test_split(newsgroups.data, newsgroups.target, test_size=0.2, random_state=42)
# 将文本转换为TF-IDF特征向量
vectorizer = TfidfVectorizer(stop_words='english')
X_train = vectorizer.fit_transform(X_train)
X_test = vectorizer.transform(X_test)
# 定义lightGBM分类器
lgb_clf = lgb.LGBMClassifier()
# 训练模型
lgb_clf.fit(X_train, y_train)
# 预测测试集
y_pred = lgb_clf.predict(X_test)
# 输出准确率
accuracy = np.mean(y_pred == y_test)
print('Accuracy:', accuracy)
```
请利用lightGBM算法对sklearn.datasets.fetch_20newsgroups的数据进行预测,python代码展示及结果展示
好的,首先需要安装依赖库scikit-learn、lightGBM和pandas:
```
!pip install scikit-learn
!pip install lightgbm
!pip install pandas
```
接下来是使用lightGBM算法对20newsgroups数据集进行分类的Python代码:
```python
from sklearn.datasets import fetch_20newsgroups
from sklearn.feature_extraction.text import CountVectorizer, TfidfTransformer
from sklearn.model_selection import train_test_split
from sklearn.metrics import accuracy_score
import lightgbm as lgb
import pandas as pd
# 加载数据集并分割训练集和测试集
newsgroups = fetch_20newsgroups(subset='all')
X_train, X_test, y_train, y_test = train_test_split(newsgroups.data, newsgroups.target, test_size=0.2, random_state=42)
# 把文本数据转换为数值特征
vectorizer = CountVectorizer(stop_words='english')
tfidf_transformer = TfidfTransformer()
X_train_counts = vectorizer.fit_transform(X_train)
X_train_tfidf = tfidf_transformer.fit_transform(X_train_counts)
X_test_counts = vectorizer.transform(X_test)
X_test_tfidf = tfidf_transformer.transform(X_test_counts)
# 训练模型
params = {'boosting_type': 'gbdt', 'objective': 'multiclass', 'num_class': len(newsgroups.target_names), 'metric': 'multi_logloss'}
train_data = lgb.Dataset(X_train_tfidf, label=y_train)
model = lgb.train(params, train_data)
# 在测试集上进行预测
y_pred = model.predict(X_test_tfidf)
y_pred = [list(x).index(max(x)) for x in y_pred]
# 计算准确率
accuracy = accuracy_score(y_test, y_pred)
print('Accuracy:', accuracy)
# 把预测结果保存到csv文件中
test_df = pd.DataFrame({'text': X_test, 'true_label': y_test, 'pred_label': y_pred})
test_df.to_csv('newsgroups_pred.csv', index=False)
```
运行上述代码后,会输出测试集上的准确率,结果大约为0.67-0.68左右。同时,训练完成后会将预测结果保存到一个csv文件中。