python - 提取具有特殊值(value)的数据

Question

我有一个像这样的数据集:

df = pd.DataFrame({'scientist':["Wendelaar Bonga"," Sjoerd E.", "Grätzel"," Michael", "Willett", "Walter C.",
                             "Kessler", "Ronald C.", "Witten, Edward", "Wang, Zhong Lin"],
               'SubjectField': ["Biomedical Engineering", "Inorganic & Nuclear Chemistry",
                                "Organic Chemistry", "Biomedical Engineering", "Developmental Biology",
                                "Mechanical Engineering & Transports", "Biomedical Engineering", "Microbiology",
                                "Cardiovascular System & Hematology", "Biomedical Engineering"]})

我想统计每个学科领域的科学家人数，并提取超过 2 位科学家的学科领域。这是我计算科学家数量的代码

 number_of_scientists_in_fields=data.groupby(['SubjectField'])['scientist'].count()

如何提取超过 2 位科学家的学科领域？

Answer 1

使用value_counts ，如下:

fields = df.value_counts('SubjectField').to_frame('count')
res = fields[fields['count'] > 2]
print(res)

输出

                        count
SubjectField                 
Biomedical Engineering      4