如何用pandas从训练数据中随机抽取特定类别的Python实例？

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废话真多，一句也不想多说，直接看代码吧！

废话真的一句也不想多说，直接看代码吧！

# -*- coding: utf-8 -*- import numpy from sklearn import metrics from sklearn.svm import LinearSVC from sklearn.naive_bayes import MultinomialNB from sklearn import linear_model from sklearn.datasets import load_iris from sklearn.cross_validation import train_test_split from sklearn.preprocessing import OneHotEncoder, StandardScaler from sklearn import cross_validation from sklearn import preprocessing import scipy as sp from sklearn.linear_model import LogisticRegression from sklearn.feature_selection import SelectKBest ,chi2 import pandas as pd from sklearn.preprocessing import OneHotEncoder #import iris_data ''' creativeID,userID,positionID,clickTime,conversionTime,connectionType, telecomsOperator,appPlatform,sitesetID,positionType,age,gender, education,marriageStatus,haveBaby,hometown,residence,appID,appCategory,label ''' def test(): df = pd.read_table("/var/lib/mysql-files/data1.csv", sep=",") df1 = df[["connectionType","telecomsOperator","appPlatform","sitesetID", "positionType","age","gender","education","marriageStatus", "haveBaby","hometown","residence","appCategory","label"]] print df1["label"].value_counts() N_data = df1[df1["label"]==0] P_data = df1[df1["label"]==1] N_data = N_data.sample(n=P_data.shape[0], frac=None, replace=False, weights=None, random_state=2, axis=0) #print df1.loc[:,"label"]==0 print P_data.shape print N_data.shape data = pd.concat([N_data,P_data]) print data.shape data = data.sample(frac=1).reset_index(drop=True) print data[["label"]] return

补充拓展：pandas实现对dataframe抽样

随机抽样

import pandas as pd #对dataframe随机抽取2000个样本 pd.sample(df, n=2000)

分层抽样

利用sklean中的函数灵活进行抽样

from sklearn.model_selection import train_test_split #y是在X中的某一个属性列 X_train, X_test, y_train, y_test = train_test_split(X,y, test_size=0.2, stratify=y)

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