过滤掉出现次数少的行---pandaa.groupby

需求：过滤掉pandas   DataFrame中出现次数较少的行，可以采用下面的写法：df为待过滤数据

df_family_car = df.groupby("PLATE_INFO_EX").filter(lambda x: (len(x) > 500 and len(x)<1000))

详细研究groupby用法，参考链接：https://blog.youkuaiyun.com/songbinxu/article/details/79839363

https://blog.youkuaiyun.com/youngbit007/article/details/54288603/

新建数据：

import pandas as pd
df = pd.DataFrame({'key1':list('aabba'),
                  'key2': ['one','two','one','two','one'],
                  'data1': np.random.randn(5),
                  'data2': np.random.randn(5)})

df
Out[83]: 
  key1 key2     data1     data2
0    a  one -0.643930 -0.856232
1    a  two  0.863575 -0.577838
2    b  one  0.261961 -1.045156
3    b  two  0.820736  0.790127
4    a  one -0.991311