删除行和ValueError数组是不同的长度

Question

我的数据框有子类别,每个类别下(cat,dog,bird),统计信息呈现.我需要删除行,如果它们包含count和中的信息freq,并且只保留行sd和mean值.有些值是 NaN.

ValueError 发生在我的代码中.

DF:

 var    stats    A     B     C
 cat     mean    2     3     4
 NaN     sd      2     1     3
 NaN     count   5     2     6
 NaN     freq    3     1     19
 dog     mean    8     1     2
 NaN     sd      2     1     3
 NaN     count   4     6     1
 NaN     freq    3     1     19   
 bird    mean    2     3     4
 NaN     sd      2     1     3
 NaN     count   5     2     6
 NaN     freq    NaN   NaN   NaN 

我的代码:

rows = ['count', 'freq']
df = [df.stats != rows]

预期结果

 var    stats    A     B     C
 cat     mean    2     3     4
 NaN     sd      2     1     3
 dog     mean    8     1     2
 NaN     sd      2     1     3   
 bird    mean    2     3     4
 NaN     sd      2     1     3

错误:

File "pandas/_libs/lib.pyx", line 805, in pandas._libs.lib.vec_compare 
(pandas/_libs/lib.c:14288)
ValueError: Arrays were different lengths: 819 vs 9

我不确定如何检查数组长度,但在我的Excel电子表格中,所有列和行都具有相同的长度.这个错误是由我的数据中的NaN /空单元格引起的吗？

谢谢!

Answer 1

!=不会在这里工作.使用pd.Series.isin以获得掩蔽,那么你就用它来过滤你的数据帧.

m = ~df.stats.isin(['count', 'freq'])
print(m)
0      True
1      True
2     False
3     False
4      True
5      True
6     False
7     False
8      True
9      True
10    False
11    False
Name: stats, dtype: bool

print(df[m])
    var stats    A    B    C
0   cat  mean  2.0  3.0  4.0
1   NaN    sd  2.0  1.0  3.0
4   dog  mean  8.0  1.0  2.0
5   NaN    sd  2.0  1.0  3.0
8  bird  mean  2.0  3.0  4.0
9   NaN    sd  2.0  1.0  3.0