python之为什么 "assert 211 == 211"失败了

这失败了:

train_data = pd.concat([train_cancelled, train_not_cancelled]).as_matrix() 
 
mat_col_size = int((num_days * 3) + 1) 
 
assert isinstance(mat_col_size, int), "mat_col_size is not an int" 
assert isinstance(train_data.shape[1], int), "train_data.shape[1] is not an int" 
 
assert train_data.shape[1] == mat_col_size, \ 
    "Number of columns in train data must be 'num_fetaures + 1 = {0:d}' (label) but is '{0:1}'." \ 
        .format(mat_col_size, train_data.shape[1]) 

它将打印:

AssertionError: Number of columns in train data must be 'num_fetaures + 1 = 211' (label) but is '211'. 

我的问题是:有多少不同的事情会出错并导致失败，因为我根本找不到问题或我的代码没有进行第三次断言的原因!