![](/img/trans.png)
[英]Python : How to interpret the result of logistic regression by sm.Logit
[英]Logistic Regression in python using Logit() and fit()
我正在尝试使用以下代码在python中执行逻辑回归-
from patsy import dmatrices
import numpy as np
import pandas as pd
import statsmodels.api as sm
df=pd.read_csv('C:/Users/Documents/titanic.csv')
df=df.drop(['ticket','cabin','name','parch','sibsp','fare'],axis=1) #remove columns from table
df=df.dropna() #dropping null values
formula = 'survival ~ C(pclass) + C(sex) + age'
df_train = df.iloc[ 0: 6, : ]
df_test = df.iloc[ 6: , : ]
#spliting data into dependent and independent variables
y_train,x_train = dmatrices(formula, data=df_train,return_type='dataframe')
y_test,x_test = dmatrices(formula, data=df_test,return_type='dataframe')
#instantiate the model
model = sm.Logit(y_train,x_train)
res=model.fit()
res.summary()
我在这条线上出现错误-
--->res=model.fit()
我在数据集中没有缺失的值。 但是,我的数据集很小,只有10个条目。 我不确定这里出了什么问题,我该如何解决? 我正在Jupyter笔记本中运行该程序。 整个错误消息如下:
---------------------------------------------------------------------------
PerfectSeparationError Traceback (most recent call last)
<ipython-input-37-c6a47ec170d5> in <module>()
19 y_test,x_test = dmatrices(formula, data=df_test,return_type='dataframe')
20 model = sm.Logit(y_train,x_train)
---> 21 res=model.fit()
22 res.summary()
C:\Program Files\Anaconda3\lib\site-packages\statsmodels\discrete\discrete_model.py in fit(self, start_params, method, maxiter, full_output, disp, callback, **kwargs)
1374 bnryfit = super(Logit, self).fit(start_params=start_params,
1375 method=method, maxiter=maxiter, full_output=full_output,
-> 1376 disp=disp, callback=callback, **kwargs)
1377
1378 discretefit = LogitResults(self, bnryfit)
C:\Program Files\Anaconda3\lib\site-packages\statsmodels\discrete\discrete_model.py in fit(self, start_params, method, maxiter, full_output, disp, callback, **kwargs)
201 mlefit = super(DiscreteModel, self).fit(start_params=start_params,
202 method=method, maxiter=maxiter, full_output=full_output,
--> 203 disp=disp, callback=callback, **kwargs)
204
205 return mlefit # up to subclasses to wrap results
C:\Program Files\Anaconda3\lib\site-packages\statsmodels\base\model.py in fit(self, start_params, method, maxiter, full_output, disp, fargs, callback, retall, skip_hessian, **kwargs)
423 callback=callback,
424 retall=retall,
--> 425 full_output=full_output)
426
427 #NOTE: this is for fit_regularized and should be generalized
C:\Program Files\Anaconda3\lib\site-packages\statsmodels\base\optimizer.py in _fit(self, objective, gradient, start_params, fargs, kwargs, hessian, method, maxiter, full_output, disp, callback, retall)
182 disp=disp, maxiter=maxiter, callback=callback,
183 retall=retall, full_output=full_output,
--> 184 hess=hessian)
185
186 # this is stupid TODO: just change this to something sane
C:\Program Files\Anaconda3\lib\site-packages\statsmodels\base\optimizer.py in _fit_newton(f, score, start_params, fargs, kwargs, disp, maxiter, callback, retall, full_output, hess, ridge_factor)
246 history.append(newparams)
247 if callback is not None:
--> 248 callback(newparams)
249 iterations += 1
250 fval = f(newparams, *fargs) # this is the negative likelihood
C:\Program Files\Anaconda3\lib\site-packages\statsmodels\discrete\discrete_model.py in _check_perfect_pred(self, params, *args)
184 np.allclose(fittedvalues - endog, 0)):
185 msg = "Perfect separation detected, results not available"
--> 186 raise PerfectSeparationError(msg)
187
188 def fit(self, start_params=None, method='newton', maxiter=35,
PerfectSeparationError: Perfect separation detected, results not available
您具有完美的分隔,这意味着您的数据可以被超平面完全分隔。 发生这种情况时,您的参数的最大似然估计是无限的,因此会导致错误。
完美分离的示例:
Gender Outcome
male 1
male 1
male 0
female 0
female 0
在这种情况下,如果得到女性观察,则可以100%肯定地知道结果将为0。也就是说,我的数据可以完美区分结果。 没有不确定性,并且寻找我的系数的数值计算也不收敛。
根据您的错误,您正在发生类似的事情。 仅用10个条目,您就可以想象这将如何发生,而不是拥有1000条或类似的条目。 因此获取更多数据:)
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.