第十四周作业
作业取自https://nbviewer.jupyter.org/github/schmit/cme193-ipython-notebooks-lecture/blob/master/Exercises.ipynb
Part 1
For each of the four datasets...
- Compute the mean and variance of both x and y
- Compute the correlation coefficient between x and y
- Compute the linear regression line: y=β0+β1x+ϵy=β0+β1x+ϵ (hint: use statsmodels and look at the Statsmodels notebook
panda库有求均值的函数mean()，方差var()，相关系数corr()。另外，线性回归用到了statsmodels库中的ols，最后用summary提取出相关数据。(方法由https://nbviewer.jupyter.org/github/schmit/cme193-ipython-notebooks-lecture/blob/master/3.%20Statsmodels.ipynb提供)
代码如下
anascombe = pd.read_csv('https://raw.githubusercontent.com/schmit/cme193-ipython-notebooks-lecture/master/data/anscombe.csv')
print("均值为：")
print(anascombe.groupby(['dataset']).mean())
print("\n方差为：")
print(anascombe.groupby(['dataset']).var())
print("\n相关系数为：")
print(anascombe.groupby(['dataset']).corr())
print("\n线性回归：")
for i in range(4):
X = sm.add_constant(np.array(anascombe[i:i+11].x))
Y = np.array(anascombe[i:i+11].y)
res = sm.OLS(Y, X).fit()
print(res.summary())结果
均值为：
x y
dataset
I 9.0 7.500909
II 9.0 7.500909
III 9.0 7.500000
IV 9.0 7.500909
方差为：
x y
dataset
I 11.0 4.127269
II 11.0 4.127629
III 11.0 4.122620
IV 11.0 4.123249
相关系数为：
x y
dataset
I x 1.000000 0.816421
y 0.816421 1.000000
II x 1.000000 0.816237
y 0.816237 1.000000
III x 1.000000 0.816287
y 0.816287 1.000000
IV x 1.000000 0.816521
y 0.816521 1.000000
线性回归：
OLS Regression Results
==============================================================================
Dep. Variable: y R-squared: 0.667
Model: OLS Adj. R-squared: 0.629
Method: Least Squares F-statistic: 17.99
Date: Sun, 10 Jun 2018 Prob (F-statistic): 0.00217
Time: 22:36:49 Log-Likelihood: -16.841
No. Observations: 11 AIC: 37.68
Df Residuals: 9 BIC: 38.48
Df Model: 1
Covariance Type: nonrobust
==============================================================================
coef std err t P>|t| [0.025 0.975]
------------------------------------------------------------------------------
const 3.0001 1.125 2.667 0.026 0.456 5.544
x1 0.5001 0.118 4.241 0.002 0.233 0.767
==============================================================================
Omnibus: 0.082 Durbin-Watson: 3.212
Prob(Omnibus): 0.960 Jarque-Bera (JB): 0.289
Skew: -0.122 Prob(JB): 0.865
Kurtosis: 2.244 Cond. No. 29.1
==============================================================================
Warnings:
[1] Standard Errors assume that the covariance matrix of the errors is correctly specified.
OLS Regression Results
==============================================================================
Dep. Variable: y R-squared: 0.657
Model: OLS Adj. R-squared: 0.619
Method: Least Squares F-statistic: 17.24
Date: Sun, 10 Jun 2018 Prob (F-statistic): 0.00247
Time: 22:36:49 Log-Likelihood: -17.291
No. Observations: 11 AIC: 38.58
Df Residuals: 9 BIC: 39.38
Df Model: 1
Covariance Type: nonrobust
==============================================================================
coef std err t P>|t| [0.025 0.975]
------------------------------------------------------------------------------
const 3.0101 1.172 2.569 0.030 0.359 5.661
x1 0.5101 0.123 4.153 0.002 0.232 0.788
==============================================================================
Omnibus: 0.562 Durbin-Watson: 3.011
Prob(Omnibus): 0.755 Jarque-Bera (JB): 0.578
Skew: -0.304 Prob(JB): 0.749
Kurtosis: 2.057 Cond. No. 29.1
==============================================================================
Warnings:
[1] Standard Errors assume that the covariance matrix of the errors is correctly specified.
OLS Regression Results
==============================================================================
Dep. Variable: y R-squared: 0.633
Model: OLS Adj. R-squared: 0.593
Method: Least Squares F-statistic: 15.54
Date: Sun, 10 Jun 2018 Prob (F-statistic): 0.00339
Time: 22:36:49 Log-Likelihood: -17.627
No. Observations: 11 AIC: 39.25
Df Residuals: 9 BIC: 40.05
Df Model: 1
Covariance Type: nonrobust
==============================================================================
coef std err t P>|t| [0.025 0.975]
------------------------------------------------------------------------------
const 3.2156 1.208 2.662 0.026 0.483 5.948
x1 0.4993 0.127 3.943 0.003 0.213 0.786
==============================================================================
Omnibus: 1.155 Durbin-Watson: 2.623
Prob(Omnibus): 0.561 Jarque-Bera (JB): 0.881
Skew: -0.467 Prob(JB): 0.644
Kurtosis: 1.975 Cond. No. 29.1
==============================================================================
Warnings:
[1] Standard Errors assume that the covariance matrix of the errors is correctly specified.
OLS Regression Results
==============================================================================
Dep. Variable: y R-squared: 0.729
Model: OLS Adj. R-squared: 0.699
Method: Least Squares F-statistic: 24.24
Date: Sun, 10 Jun 2018 Prob (F-statistic): 0.000820
Time: 22:36:49 Log-Likelihood: -16.074
No. Observations: 11 AIC: 36.15
Df Residuals: 9 BIC: 36.94
Df Model: 1
Covariance Type: nonrobust
==============================================================================
coef std err t P>|t| [0.025 0.975]
------------------------------------------------------------------------------
const 2.9415 1.049 2.804 0.021 0.568 5.314
x1 0.5415 0.110 4.924 0.001 0.293 0.790
==============================================================================
Omnibus: 1.370 Durbin-Watson: 2.795
Prob(Omnibus): 0.504 Jarque-Bera (JB): 0.835
Skew: -0.307 Prob(JB): 0.659
Kurtosis: 1.798 Cond. No. 29.1
==============================================================================Part 2
Using Seaborn, visualize all four datasets.
hint: use sns.FacetGrid combined with plt.scatter
在以前的联系里我已经介绍过seaborn，该库对matplotlib进行了二次封装，各种函数相比matplotlib更加简便，且画图效果更好。
代码如下
pic = sns.FacetGrid(anascombe, col='dataset')
pic = pic.map(plt.scatter, 'x', 'y')结果
