样本数不一致是什么意思？

Question

我正在使用 scikit 的逻辑回归，但我不断收到消息：

Found input variables with inconsistent numbers of samples: [90000, 5625]

在下面的代码中，我删除了包含文本的列，然后将日期拆分为训练和测试集。

import numpy as np
import pandas as pd
import matplotlib 
import matplotlib.pyplot as plt
from scipy import stats
from sklearn import datasets, linear_model
from sklearn.model_selection import train_test_split

dataset = pd.read_csv("/Users/An/Desktop/data/telco.csv", na_values = ' ') 
dataset = dataset.dropna(axis = 0)

dataset = dataset.replace({'Yes':1, 'Fiber optic': 1, 'DSL':1, 'No':0, 'No phone service':0, 'No internet service':0})
dataset = dataset.drop('Contract', axis  =1)
dataset = dataset.drop('PaymentMethod',axis  =1)
dataset = dataset.drop('customerID',axis  =1)
dataset = dataset.drop('gender',axis  =1)

for i in list(['tenure', 'MonthlyCharges', 'TotalCharges']):
    sd = np.std(dataset[i])
    mean = np.mean(dataset[i])
    dataset[i] = (dataset[i] - mean) / sd

total = pd.DataFrame(dataset)  
data_train, data_test = train_test_split(total, test_size=0.2)
data_train = data_train.values
data_test = data_test.values

from sklearn.linear_model import LogisticRegression

clf = LogisticRegression(C=1e9)
clf = clf.fit(data_train[:,0:16], data_train[:,16])
print clf.intercept_, clf.coef_

有人可以解释错误消息的含义并帮助我弄清楚为什么会收到它吗？

Answer 1

在倒数第二行，data_train.reshape(-1, 1) 导致了您的问题。删除 reshape 对您有帮助。

原因

LogisticRegression.fit 期望 x 和 y 具有相同的 shape[0]，但您正在将 x 从 (n, m) 重塑为 (n*m, 1)。

这是复制的形状：

import numpy as np

df = np.ndarray((2000,10))
x, y  = df[:, 2:9], df[:, 9]
x.shape, y.shape # << what you should give to `clf.fit`
# ((2000, 7), (2000, ))

x.reshape(-1, 1).shape, y.shape # << what you ARE giving to `clf.fit`,
# ((14000, 1), (2000,))         # << which is causing the problem