San Francisco Crime Classification
第二个 实战kaggle 的例子，，
可以加上计算score分析，，
代码如下：
import pandas as pd
import numpy as np
#用pandas载入csv训练数据，并解析第一列为日期格式
train=pd.read_csv('train.csv', parse_dates = ['Dates'])
test=pd.read_csv('test.csv', parse_dates = ['Dates'])
#用LabelEncoder对不同的犯罪类型编号
leCrime = preprocessing.LabelEncoder()
crime = leCrime.fit_transform(train.Category)
#因子化星期几，街区，小时等特征
days = pd.get_dummies(train.DayOfWeek)
district = pd.get_dummies(train.PdDistrict)
hour = train.Dates.dt.hour
hour = pd.get_dummies(hour)
#组合特征
trainData = pd.concat([hour, days, district], axis=1)
trainData['crime']=crime
#对于测试数据做同样的处理
days = pd.get_dummies(test.DayOfWeek)
district = pd.get_dummies(test.PdDistrict)
hour = test.Dates.dt.hour
hour = pd.get_dummies(hour)
testData = pd.concat([hour, days, district], axis=1)
trainData
from sklearn.cross_validation import train_test_split
from sklearn import preprocessing
from sklearn.metrics import log_loss
from sklearn.naive_bayes import BernoulliNB
from sklearn.linear_model import LogisticRegression
import time
# 只取星期几和街区作为分类器输入特征
features = ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday', 'BAYVIEW', 'CENTRAL', 'INGLESIDE', 'MISSION',
'NORTHERN', 'PARK', 'RICHMOND', 'SOUTHERN', 'TARAVAL', 'TENDERLOIN']
hourFea = [x for x in range(0,24)]
features = features + hourFea
# 分割训练集(3/5)和测试集(2/5)
training, validation = train_test_split(trainData, train_size=.60)
# 朴素贝叶斯建模，计算log_loss
model = BernoulliNB()
nbStart = time.time()
model.fit(training[features], training['crime'])
nbCostTime = time.time() - nbStart
predicted = np.array(model.predict_proba(validation[features]))
print ("朴素贝叶斯建模耗时 %f 秒" %(nbCostTime))
print ("朴素贝叶斯log损失为 %f" %(log_loss(validation['crime'], predicted)))
#逻辑回归建模，计算log_loss
model = LogisticRegression(C=.01)
lrStart= time.time()
model.fit(training[features], training['crime'])
lrCostTime = time.time() - lrStart
predicted = np.array(model.predict_proba(validation[features]))
log_loss(validation['crime'], predicted)
print ("逻辑回归建模耗时 %f 秒" %(lrCostTime))
print ("逻辑回归log损失为 %f" %(log_loss(validation['crime'], predicted)))
