using regex to match patterns from one column and creating a new column based on the column attribute names

Question

I have a Pandas DataFrame of the form:

Current

product_typ

[Milo, Milk, Sugar]
[Water, Tea, Milo]
[Bread, Water]
[Bread, Water, Milo]
[Salt, Water, Milo]
[Milo, Milk, Water, Bread]
[Salt, Milk, Bread]
[Milo, Milk]

I would like to create a new column with regex of the form. Keep in mind that it is a Pandas DataFrame

Expected Output

product_typ                          matched_col

[Milo, Milk, Sugar]                Product_Milo_Milk_Sugar
[Water, Tea, Milo]                 Product_Water_Tea_Milo
[Bread, Water]                     Product_Bread_Water
[Bread, Water, Milo]               Product_Bread_Water_Milo
[Salt, Water, Milo]                Product_Salt_Water_Milo
[Milo, Milk, Water, Bread]         Product_Milo_Milk_Water_Bread
[Salt, Milk, Bread]                Product_Salt_Milk_Bread
[Milo, Milk]                       Product_Milo_Milk

I tried to attempt this with str.findall matching the pattern works but the replacement got me quite thinking.

What have you tried so far?

Devansh Soni
– Devansh Soni

2020-04-20 15:41:17 +00:00
Commented Apr 20, 2020 at 15:41 — Devansh Soni
– Devansh Soni, Commented Apr 20, 2020 at 15:41

Mayank Porwal · Accepted Answer · 2020-04-20 15:41:12Z

2

Like this maybe:

df['matched_col'] = ['_'.join(map(str, l)) for l in df['product_typ']]

OR

In [1687]: df['matched_col'] = df['product_typ'].apply('_'.join)

Example:

In [1681]: df = pd.DataFrame({'A': [['a','b','c'], ['b','c']]})                                                                                                                                             

In [1682]: df                                                                                                                                                                                               
Out[1682]: 
           A
0  [a, b, c]
1     [b, c]

In [1684]: df['b'] = ['_'.join(map(str, l)) for l in df['A']]                                                                                                                                               

In [1685]: df                                                                                                                                                                                               
Out[1685]: 
           A      b
0  [a, b, c]  a_b_c
1     [b, c]    b_c

answered Apr 20, 2020 at 15:41

Mayank Porwal

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2 Comments

JA-pythonista Over a year ago

I get an error TypeError: sequence item 0: expected str instance, float found and when I check the first item, this is it --> ['Milk', 'Milo']

Mayank Porwal Over a year ago

Please apply this only on the column which has lists not on the entire dataframes. Another reason could be that this column contains float values. Try to apply this on a sample of dataframe which you are sure that it contains proper list of string values.

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