how to remove empty series from list in Python

Question

I have a list which looks something like this.

DB
Out[469]: 
[[3    523
Name: order_id, dtype: object], 0    [526, 533]
Name: order_id, dtype: object, Series([], Name: order_id, dtype: object)]

And what I want it to look like this.

DB
[['523',['526','533']]]

I am doing following in python

 DB[0][0].values[0]
 Out[462]: '523'

 DB[1][0]
 Out[463]: ['526', '533']

And to remove empty series

 [x for x in DB if x != []]

But It doesn't work. I want a for loop which will iterate through DB and give me final output. Please help.

@AntonProtopopov I can't post the code because its a long function. — Neil
– Neil, Commented Jan 20, 2016 at 12:43
@AntonProtopopov I get this after slicing a dataframe by groupby and them I am appending it to the empty list. — Neil
– Neil, Commented Jan 20, 2016 at 12:45
Can you post raw data and code to reproduce your series, at the moment this is all very ambiguous — EdChum
– EdChum, Commented Jan 20, 2016 at 12:57

EdChum · Accepted Answer · 2016-01-20 12:15:35Z

2

test for the len inside your list comprehension to remove it:

In [150]:
l=[pd.Series(['asda']), pd.Series(), pd.Series([9,12,4])]
l

Out[150]:
[0    asda
 dtype: object, Series([], dtype: float64), 0     9
 1    12
 2     4
 dtype: int64]

In [153]:    
[x for x in l if len(x)>0]

Out[153]:
[0    asda
 dtype: object, 0     9
 1    12
 2     4
 dtype: int64]

You can see that the lengths are different:

In [155]:
print(len(l))
print(len([x for x in l if len(x)>0]))

3
2

answered Jan 20, 2016 at 12:15

EdChum

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10 Comments

Neil Over a year ago

Yup, len(x)>0 is working and its removing empty series,but how can i convert the elements to the desired format

EdChum Over a year ago

you mean [x.values.tolist() for x in l if len(x)>0]?

Neil Over a year ago

Yup. I ran [x.values.tolist() for x in l if len(x)>0] but its giving me error AttributeError: 'list' object has no attribute 'values'

Anton Protopopov Over a year ago

Try that: [x.values.tolist() if type(x)==pd.Series else x for x in l if len(x) > 0]

Neil Over a year ago

@AntonProtopopov Thanks for your help. I ran what you suggested its giving me following output

[x.values.tolist() if type(x)==pd.Series else x for x in DB if len(x) > 0] Out[482]:  [[3    523   Name: order_id, dtype: object], [['526', '533']]]

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