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Expanding strings vertically in a DataFrame in Pandas
schedule Aug 12, 2023
Last updated local_offer
Tags Python●Pandas
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To expand strings vertically in Pandas, use the DataFrame's explode(~) method.
As an example, consider the following DataFrame:
df = pd.DataFrame({"A":["a,b","b,c"],"B":[4,5]})df
A B0 a,b 41 b,c 5
Solution
To split the strings of column A by ,, and then vertically expand the rows:
df["A"] = df["A"].str.split(",")df = df.explode("A")df
A B0 a 40 b 41 b 51 c 5
Explanation
Here, we are first splitting the strings of column A by , using str.split(","):
df["A"] = df["A"].str.split(",")df
A B0 [a, b] 41 [b, c] 5
Next, we used the explode(~) method to let each element of the lists have its own row:
df.explode("A")
A B0 a 40 b 41 b 51 c 5
Supplement - resetting the index
Notice how the resulting DataFrame has duplicate indices [0,0,1,1], which is bad practise in Pandas. To reset the index to the default integer index, call reset_index(drop=True) like so:
df.reset_index(drop=True)
A B0 a 41 b 42 b 53 c 5
Here, the parameter drop=True is needed - otherwise the current index will become included as a column.
Published by Isshin Inada
Edited by 0 others
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