为什么在 Python 中使用 anova_lm 显示形状未对齐？

Question

基于这个问题在此处输入链接描述，我使用 statsmodels 在 python 中实现方差分析。我的数据在 Pandas DataFrame 中并且country是一个分类变量。

def anova(data):

    mod = ols('C(country) ~ playerRank+playerGames', data=data).fit()
    aov_table = sm.stats.anova_lm(mod, typ=2)
    print aov_table

当我使用上述功能时，它显示：

 File "<ipython-input-32-e77ae8a55692>", line 1, in <module>
    aov_table = sm.stats.anova_lm(mod, typ=2)
  File "C:\ProgramData\Anaconda2\lib\site-packages\statsmodels\stats\anova.py", line 326, in anova_lm
    return anova_single(model, **kwargs)
  File "C:\ProgramData\Anaconda2\lib\site-packages\statsmodels\stats\anova.py", line 83, in anova_single
    robust)
  File "C:\ProgramData\Anaconda2\lib\site-packages\statsmodels\stats\anova.py", line 178, in anova2_lm_single
    cov = _get_covariance(model, None)
  File "C:\ProgramData\Anaconda2\lib\site-packages\statsmodels\stats\anova.py", line 15, in _get_covariance
    return model.cov_params()
  File "C:\ProgramData\Anaconda2\lib\site-packages\statsmodels\base\wrapper.py", line 95, in wrapper
    obj = data.wrap_output(func(results, *args, **kwargs), how)
  File "C:\ProgramData\Anaconda2\lib\site-packages\statsmodels\base\model.py", line 1180, in cov_params
    scale = self.scale
  File "C:\ProgramData\Anaconda2\lib\site-packages\statsmodels\tools\decorators.py", line 97, in __get__
    _cachedval = self.fget(obj)
  File "C:\ProgramData\Anaconda2\lib\site-packages\statsmodels\regression\linear_model.py", line 1510, in scale
    return np.dot(wresid, wresid) / self.df_resid
ValueError: shapes (10481,41) and (10481,41) not aligned: 41 (dim 1) != 10481 (dim 0)

编辑：

我试过这种方法如下：

y, X = dmatrices('CountryCode ~ playerRank+playerGames', data=data[[['playerRank', 'playerGames', 'CountryCode']]], return_type='dataframe')
mod = sm.OLS(y, X)
res = mod.fit()
res.summary()

aov_table = sm.stats.anova_lm(res, typ=2)
print aov_table

它显示以下错误：

    Traceback (most recent call last):
  File "C:\ProgramData\Anaconda2\lib\site-packages\IPython\core\interactiveshell.py", line 2881, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-13-e9f27287c5da>", line 1, in <module>
    aov_table = sm.stats.anova_lm(res, typ=2)
  File "C:\ProgramData\Anaconda2\lib\site-packages\statsmodels\stats\anova.py", line 326, in anova_lm
    return anova_single(model, **kwargs)
  File "C:\ProgramData\Anaconda2\lib\site-packages\statsmodels\stats\anova.py", line 68, in anova_single
    design_info = model.model.data.design_info
AttributeError: 'PandasData' object has no attribute 'design_info'