pandas 包含数组的熊猫系列
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pandas series containing arrays
提问by toast
I have a pandas dataframe column which looks a little like:
我有一个看起来有点像的Pandas数据框列：
Out[67]:
0 ["cheese", "milk...
1 ["yogurt", "cheese...
2 ["cheese", "cream"...
3 ["milk", "cheese"...
now, ultimately I would like this as a flat list, but in attempting to flatten this, i noticed that pandas treats ["cheese", "milk", "cream"]as strrather than list
现在，最终我希望将其作为一个平面列表，但是在试图将其展平时，我注意到大Pandas将其["cheese", "milk", "cream"]视为str而不是list
How would i go about flattening this so I end up with:
我将如何将其展平，因此我最终得到：
["cheese", "milk", "yogurt", "cheese", "cheese"...]
[EDIT] So the answer given below appears to be:
[编辑] 所以下面给出的答案似乎是：
s = pd.Series(["['cheese', 'milk']", "['yogurt', 'cheese']", "['cheese', 'cream']"])
s = pd.Series(["['cheese', 'milk']", "['yogurt', 'cheese']", "['cheese', 'cream']"])
s = s.str.strip("[]")
df = s.str.split(',', expand=True)
df = df.applymap(lambda x: x.replace("'", '').strip())
l = df.values.flatten()
print (l.tolist())
Which is great, question answered, answer accepted but it strikes me as rather inelegant solution.
这很好，问题得到回答，答案被接受，但在我看来，这是相当不雅的解决方案。
采纳答案by jezrael
You can use numpy.flattenand then flat nested lists- see:
您可以使用numpy.flatten然后平面嵌套lists-请参阅：
print df
a
0 [cheese, milk]
1 [yogurt, cheese]
2 [cheese, cream]
print df.a.values
[[['cheese', 'milk']]
[['yogurt', 'cheese']]
[['cheese', 'cream']]]
l = df.a.values.flatten()
print l
[['cheese', 'milk'] ['yogurt', 'cheese'] ['cheese', 'cream']]
print [item for sublist in l for item in sublist]
['cheese', 'milk', 'yogurt', 'cheese', 'cheese', 'cream']
EDIT:
编辑：
You can try:
你可以试试：
import pandas as pd
s = pd.Series(["['cheese', 'milk']", "['yogurt', 'cheese']", "['cheese', 'cream']"])
#remove []
s = s.str.strip('[]')
print s
0 'cheese', 'milk'
1 'yogurt', 'cheese'
2 'cheese', 'cream'
dtype: object
df = s.str.split(',', expand=True)
#remove ' and strip empty string
df = df.applymap(lambda x: x.replace("'", '').strip())
print df
0 1
0 cheese milk
1 yogurt cheese
2 cheese cream
l = df.values.flatten()
print l.tolist()
['cheese', 'milk', 'yogurt', 'cheese', 'cheese', 'cream']
回答by Colin
You can convert the Seriesinto a DataFrameand then call stack:
您可以将 转换Series为 aDataFrame然后调用stack：
s.apply(pd.Series).stack().tolist()
回答by Colin
To convert the column values from str to list you could use df.columnName.tolist()and for flattening you could do df.columnName.values.flatten()
要将列值从 str 转换为列表，您可以使用df.columnName.tolist()并展平您可以执行的操作df.columnName.values.flatten()
