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python-3.x - 从具有值列表的列中检索唯一值

问题描述

我有一个 df 有一列，其中的值是值列表。

我的意图是使用这里的一些技术拆分此列： Pandas split column of lists into multiple columns

但是，对于列名，我想使用这些值列表中的每个唯一值。

为了检索唯一值，我尝试了三种不同的方法。每个人都因不同的原因而失败。

当值是值列表时，有没有办法获取 Series.unique() ？

我的三个尝试，以及相关的回溯：

1)
unique_vals = splitted_interests.unique()

Traceback (most recent call last):
  File "C:/Users/Mark/PycharmProjects/main/main.py", line 68, in <module>
    unique_vals = splitted_interests.unique()
  File "C:\Users\Mark\AppData\Local\Programs\Python\Python37-32\lib\site-packages\pandas\core\series.py", line 1991, in unique
    result = super().unique()
  File "C:\Users\Mark\AppData\Local\Programs\Python\Python37-32\lib\site-packages\pandas\core\base.py", line 1405, in unique
    result = unique1d(values)
  File "C:\Users\Mark\AppData\Local\Programs\Python\Python37-32\lib\site-packages\pandas\core\algorithms.py", line 405, in unique
    uniques = table.unique(values)
  File "pandas/_libs/hashtable_class_helper.pxi", line 1767, in pandas._libs.hashtable.PyObjectHashTable.unique
  File "pandas/_libs/hashtable_class_helper.pxi", line 1718, in pandas._libs.hashtable.PyObjectHashTable._unique
TypeError: unhashable type: 'list'


2)
unique_vals = splitted_interests.apply(lambda x: x.unique())

Traceback (most recent call last):
  File "C:/Users/Mark/PycharmProjects/main/main.py", line 68, in <module>
    unique_vals = splitted_interests.apply(lambda x: x.unique())
  File "C:\Users\Mark\AppData\Local\Programs\Python\Python37-32\lib\site-packages\pandas\core\series.py", line 4045, in apply
    mapped = lib.map_infer(values, f, convert=convert_dtype)
  File "pandas/_libs/lib.pyx", line 2228, in pandas._libs.lib.map_infer
  File "C:/Users/Mark/PycharmProjects/main/main.py", line 68, in <lambda>
    unique_vals = splitted_interests.apply(lambda x: x.unique())
AttributeError: 'list' object has no attribute 'unique'

3)
unique_vals = splitted_interests.apply(lambda x: [y.unique() for y in x])

Traceback (most recent call last):
  File "C:\Users\Mark\AppData\Local\Programs\Python\Python37-32\lib\site-packages\pandas\core\series.py", line 4045, in apply
    mapped = lib.map_infer(values, f, convert=convert_dtype)
  File "pandas/_libs/lib.pyx", line 2228, in pandas._libs.lib.map_infer
  File "C:/Users/Mark/PycharmProjects/main/main.py", line 68, in <lambda>
    unique_vals = splitted_interests.apply(lambda x: [y.unique() for y in x])
  File "C:/Users/Mark/PycharmProjects/main/main.py", line 68, in <listcomp>
    unique_vals = splitted_interests.apply(lambda x: [y.unique() for y in x])
AttributeError: 'str' object has no attribute 'unique'

在运行时，带有列表的列如下所示： 在此处输入图像描述

标签： python-3.xpandas

解决方案

对于相同的排序创建字典和提取keys，解决方案在python 3.6+中工作：

df = pd.DataFrame({'JobRoleInterest':['aa,ss,ss','dd,ff','k,dd,dd,dd', 'j,gg']})
splitted_interests = df['JobRoleInterest'].str.split(',')

unique_vals = list(dict.fromkeys([y for x in splitted_interests for y in x]).keys())
print (unique_vals)
['aa', 'ss', 'dd', 'ff', 'k', 'j', 'gg']

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