我如何使用 sklearn 的 SGDClassifier return 预测 Top N 的准确率？
How can I return accuracy rates for Top N predictions using sklearn's SGDClassifier?
我正在尝试修改此 post 中的结果（如何使用 sklearn 的 SGDClassifier 获得前 3 或前 N 个预测）以获得返回的准确率，但是我得到的准确率为零和我不知道为什么。有什么想法吗？任何 thoughts/edits 将不胜感激！谢谢你。
from sklearn.feature_extraction.text import TfidfVectorizer
import numpy as np
from sklearn import linear_model
arr=['dogs cats lions','apple pineapple orange','water fire earth air', 'sodium potassium calcium']
vectorizer = TfidfVectorizer()
X = vectorizer.fit_transform(arr)
feature_names = vectorizer.get_feature_names()
Y = ['animals', 'fruits', 'elements','chemicals']
T=["eating apple roasted in fire and enjoying fresh air"]
test = vectorizer.transform(T)
clf = linear_model.SGDClassifier(loss='log')
clf.fit(X,Y)
x=clf.predict(test)
def top_n_accuracy(probs, test, n):
best_n = np.argsort(probs, axis=1)[:,-n:]
ts = np.argmax(test, axis=1)
successes = 0
for i in range(ts.shape[0]):
if ts[i] in best_n[i,:]:
successes += 1
return float(successes)/ts.shape[0]
n=2
probs = clf.predict_proba(test)
top_n_accuracy(probs, test, n)
from sklearn.feature_extraction.text import TfidfVectorizer
import numpy as np
from sklearn import linear_model
arr=['dogs cats lions','apple pineapple orange','water fire earth air', 'sodium potassium calcium']
vectorizer = TfidfVectorizer()
X = vectorizer.fit_transform(arr)
feature_names = vectorizer.get_feature_names()
Y = ['animals', 'fruits', 'elements','chemicals']
T=["eating apple roasted in fire and enjoying fresh air", "I love orange"]
test = vectorizer.transform(T)
clf = linear_model.SGDClassifier(loss='log')
clf.fit(X,Y)
x=clf.predict(test)
n=2
probs = clf.predict_proba(test)
topn = np.argsort(probs, axis = 1)[:,-n:]
这里我介绍了ground truth label vector（这些是数字索引，你需要将["elements", etc]映射到[0,1,2 etc]。这里我假设你的测试示例属于元素。
y_true = np.array([2,1])
这应该会计算你的准确度
np.mean(np.array([1 if y_true[k] in topn[k] else 0 for k in range(len(topn))]))
我最终弄清楚了这一点，尽管与上面的有点不同......
# Set Data Location:
data = 'top10000.csv'
# load the data
df = pd.read_csv(data,low_memory=False,thousands=',', encoding='latin-1')
df = df.dropna()
df = df[['CODE','DUTIES']] #select only these columns
#df = df.rename(index=float, columns={"CODE": "label", "DUTIES": "text"})
df = df.rename(columns={"CODE": "label", "DUTIES": "text"})
#Convert label to float so you don't need to encode for processing later on
df['label']=df['label'].str.replace('-', '',regex=True, case = False).str.strip()
df['label']=df['label'].str.replace('.', '',regex=True)
#df['label']=pd.to_numeric(df['label'])
df['label']=df['label'].str[1:].astype(int)
#df['label'].astype('float64', raise_on_error = True)
#split data into testing and training
train_x, valid_x, train_y, valid_y = model_selection.train_test_split(df.text, df.label,test_size=0.33, random_state=6)
#reset the index
valid_y = valid_y.reset_index(drop=True)
valid_x = valid_x.reset_index(drop=True)
# We will also copy the validation datasets to a dataframe to be able to merge later on
valid_x_df = pd.DataFrame(valid_x)
valid_y_df = pd.DataFrame(valid_y)
# Extracte features
count_vect = CountVectorizer()
X_train_counts = count_vect.fit_transform(train_x)
X_test_counts = count_vect.transform(valid_x)
# Define the model training and validation function
def TV_model(classifier, feature_vector_train, label, feature_vector_valid, valid_y, valid_x, is_neural_net=False):
# fit the training dataset on the classifier
classifier.fit(feature_vector_train, label)
# predict the top n labels on validation dataset
n = 5
#classifier.probability = True
probas = classifier.predict_proba(feature_vector_valid)
predictions = classifier.predict(feature_vector_valid)
#Identify the indexes of the top predictions
top_n_predictions = np.argsort(probas, axis = 1)[:,-n:]
#then find the associated SOC code for each prediction
top_class = classifier.classes_[top_n_predictions]
#cast to a new dataframe
top_class_df = pd.DataFrame(data=top_class)
#merge it up with the validation labels and descriptions
results = pd.merge(valid_y, valid_x, left_index=True, right_index=True)
results = pd.merge(results, top_class_df, left_index=True, right_index=True)
# Top 5 results condiions and choices
top5_conditions = [
(results.iloc[:,0] == results[0]),
(results.iloc[:,0] == results[1]),
(results.iloc[:,0] == results[2]),
(results.iloc[:,0] == results[3]),
(results.iloc[:,0] == results[4])]
top5_choices = [1, 1, 1, 1, 1]
# Fetch Top 1 Result
top1_conditions = [(results.iloc[:,0] == results[4])]
top1_choices = [1]
# Create the success columns
results['Top 5 Successes'] = np.select(top5_conditions, top5_choices, default=0)
results['Top 1 Successes'] = np.select(top1_conditions, top1_choices, default=0)
#Print the QA
print("Are Top 5 Results greater than Top 1 Result? (answer must be True): ", (sum(results['Top 5 Successes'])/results.shape[0])>(metrics.accuracy_score(valid_y, predictions)))
print("Are Top 1 Results equal from predict() and predict_proba()? (answer must be True): ", (sum(results['Top 1 Successes'])/results.shape[0])==(metrics.accuracy_score(valid_y, predictions)))
print(" ")
print("Details: ")
print("Top 5 Accuracy Rate (predict_proba)= ", sum(results['Top 5 Successes'])/results.shape[0])
#print("Top 5 Accuracy Rate (np.mean)= ", np.mean(np.array([1 if valid_y[k] in top_class[k] else 0 for k in range(len(top_class))])))
print("Top 1 Accuracy Rate (predict_proba)= ", sum(results['Top 1 Successes'])/results.shape[0])
print("Top 1 Accuracy Rate = (predict)", metrics.accuracy_score(valid_y, predictions))
# Train and validate model from example data using the function defined above
TV_model(LogisticRegression(), X_train_counts, train_y, X_test_counts, valid_y_df, valid_x_df)
我相信它的计算效率会更高，所以任何关于我如何将准确率计算转换为单一线性的建议都将不胜感激，就像上面评论中所建议的那样！
我正在尝试修改此 post 中的结果（如何使用 sklearn 的 SGDClassifier 获得前 3 或前 N 个预测）以获得返回的准确率，但是我得到的准确率为零和我不知道为什么。有什么想法吗？任何 thoughts/edits 将不胜感激！谢谢你。
from sklearn.feature_extraction.text import TfidfVectorizer
import numpy as np
from sklearn import linear_model
arr=['dogs cats lions','apple pineapple orange','water fire earth air', 'sodium potassium calcium']
vectorizer = TfidfVectorizer()
X = vectorizer.fit_transform(arr)
feature_names = vectorizer.get_feature_names()
Y = ['animals', 'fruits', 'elements','chemicals']
T=["eating apple roasted in fire and enjoying fresh air"]
test = vectorizer.transform(T)
clf = linear_model.SGDClassifier(loss='log')
clf.fit(X,Y)
x=clf.predict(test)
def top_n_accuracy(probs, test, n):
best_n = np.argsort(probs, axis=1)[:,-n:]
ts = np.argmax(test, axis=1)
successes = 0
for i in range(ts.shape[0]):
if ts[i] in best_n[i,:]:
successes += 1
return float(successes)/ts.shape[0]
n=2
probs = clf.predict_proba(test)
top_n_accuracy(probs, test, n)
from sklearn.feature_extraction.text import TfidfVectorizer
import numpy as np
from sklearn import linear_model
arr=['dogs cats lions','apple pineapple orange','water fire earth air', 'sodium potassium calcium']
vectorizer = TfidfVectorizer()
X = vectorizer.fit_transform(arr)
feature_names = vectorizer.get_feature_names()
Y = ['animals', 'fruits', 'elements','chemicals']
T=["eating apple roasted in fire and enjoying fresh air", "I love orange"]
test = vectorizer.transform(T)
clf = linear_model.SGDClassifier(loss='log')
clf.fit(X,Y)
x=clf.predict(test)
n=2
probs = clf.predict_proba(test)
topn = np.argsort(probs, axis = 1)[:,-n:]
这里我介绍了ground truth label vector（这些是数字索引，你需要将["elements", etc]映射到[0,1,2 etc]。这里我假设你的测试示例属于元素。
y_true = np.array([2,1])
这应该会计算你的准确度
np.mean(np.array([1 if y_true[k] in topn[k] else 0 for k in range(len(topn))]))
我最终弄清楚了这一点，尽管与上面的有点不同......
# Set Data Location:
data = 'top10000.csv'
# load the data
df = pd.read_csv(data,low_memory=False,thousands=',', encoding='latin-1')
df = df.dropna()
df = df[['CODE','DUTIES']] #select only these columns
#df = df.rename(index=float, columns={"CODE": "label", "DUTIES": "text"})
df = df.rename(columns={"CODE": "label", "DUTIES": "text"})
#Convert label to float so you don't need to encode for processing later on
df['label']=df['label'].str.replace('-', '',regex=True, case = False).str.strip()
df['label']=df['label'].str.replace('.', '',regex=True)
#df['label']=pd.to_numeric(df['label'])
df['label']=df['label'].str[1:].astype(int)
#df['label'].astype('float64', raise_on_error = True)
#split data into testing and training
train_x, valid_x, train_y, valid_y = model_selection.train_test_split(df.text, df.label,test_size=0.33, random_state=6)
#reset the index
valid_y = valid_y.reset_index(drop=True)
valid_x = valid_x.reset_index(drop=True)
# We will also copy the validation datasets to a dataframe to be able to merge later on
valid_x_df = pd.DataFrame(valid_x)
valid_y_df = pd.DataFrame(valid_y)
# Extracte features
count_vect = CountVectorizer()
X_train_counts = count_vect.fit_transform(train_x)
X_test_counts = count_vect.transform(valid_x)
# Define the model training and validation function
def TV_model(classifier, feature_vector_train, label, feature_vector_valid, valid_y, valid_x, is_neural_net=False):
# fit the training dataset on the classifier
classifier.fit(feature_vector_train, label)
# predict the top n labels on validation dataset
n = 5
#classifier.probability = True
probas = classifier.predict_proba(feature_vector_valid)
predictions = classifier.predict(feature_vector_valid)
#Identify the indexes of the top predictions
top_n_predictions = np.argsort(probas, axis = 1)[:,-n:]
#then find the associated SOC code for each prediction
top_class = classifier.classes_[top_n_predictions]
#cast to a new dataframe
top_class_df = pd.DataFrame(data=top_class)
#merge it up with the validation labels and descriptions
results = pd.merge(valid_y, valid_x, left_index=True, right_index=True)
results = pd.merge(results, top_class_df, left_index=True, right_index=True)
# Top 5 results condiions and choices
top5_conditions = [
(results.iloc[:,0] == results[0]),
(results.iloc[:,0] == results[1]),
(results.iloc[:,0] == results[2]),
(results.iloc[:,0] == results[3]),
(results.iloc[:,0] == results[4])]
top5_choices = [1, 1, 1, 1, 1]
# Fetch Top 1 Result
top1_conditions = [(results.iloc[:,0] == results[4])]
top1_choices = [1]
# Create the success columns
results['Top 5 Successes'] = np.select(top5_conditions, top5_choices, default=0)
results['Top 1 Successes'] = np.select(top1_conditions, top1_choices, default=0)
#Print the QA
print("Are Top 5 Results greater than Top 1 Result? (answer must be True): ", (sum(results['Top 5 Successes'])/results.shape[0])>(metrics.accuracy_score(valid_y, predictions)))
print("Are Top 1 Results equal from predict() and predict_proba()? (answer must be True): ", (sum(results['Top 1 Successes'])/results.shape[0])==(metrics.accuracy_score(valid_y, predictions)))
print(" ")
print("Details: ")
print("Top 5 Accuracy Rate (predict_proba)= ", sum(results['Top 5 Successes'])/results.shape[0])
#print("Top 5 Accuracy Rate (np.mean)= ", np.mean(np.array([1 if valid_y[k] in top_class[k] else 0 for k in range(len(top_class))])))
print("Top 1 Accuracy Rate (predict_proba)= ", sum(results['Top 1 Successes'])/results.shape[0])
print("Top 1 Accuracy Rate = (predict)", metrics.accuracy_score(valid_y, predictions))
# Train and validate model from example data using the function defined above
TV_model(LogisticRegression(), X_train_counts, train_y, X_test_counts, valid_y_df, valid_x_df)
我相信它的计算效率会更高，所以任何关于我如何将准确率计算转换为单一线性的建议都将不胜感激，就像上面评论中所建议的那样！