如何在不影响数据集本身的情况下将 aa 字符串数据拆分为同一列/单列（Python Pandas）？

Question

The data set I'm working on has got a column with zipcodes in it. Some entries only have one zipcode, some have 2, 5, or 10+ zipcodes. Like this:

Zipcode(s)
1245
5863, 5682, 1995
6978, 1123, 5659, 34554
4539, 6453

I want to do some simple analysis -- apply a value_counts() on the column to see what zipcodes are the most popular. But I can't properly do it since most cells have multiple zipcodes on them. That's also the reason why I want a way where it won't affect the dataset itself, just that specific instance where all zipcodes are split and are in one column.

I've tried splitting them into multiple columns with .str.split(',',n=20, expand=True) but that's not really what I'm looking for. I want them all split into a single column.

Answer 1

I think pandas.DataFrame.explode is what you're looking for.
With this, you take all values from lists (which you created with the split function) to a new row.

import pandas as pd

df = pd.DataFrame({
    "Zipcodes":["8000", "2000, 2002, 3003", "8000, 2002", "3004, 2004, 3003"]
})

df

(
    df.Zipcodes
    .str.replace(" ", "") # optional, if you don't need this then 
    .str.split(",")       # use ", " instead of ","
    .explode()
    .value_counts()
)

Output:

8000    2
2002    2
3003    2
2000    1
3004    1
2004    1

Answer 2

You can use this python snippet below:

import pandas as pd
df = pd.DataFrame({
    "Zipcode(s)" : ["1245", "5863, 5682, 1995", "6978, 1123, 5659, 34554", "4539, 6453"]
})
df["Zipcode(s)"] = df["Zipcode(s)"].map(lambda zcode: zcode.split(", "))
zipcodes = sum(df["Zipcode(s)"].to_list(), [])
#create dummy(empty) dataframe
dummydf = pd.DataFrame({"Zipcode(s)" : zipcodes})
print(dummydf["Zipcode(s)"].value_counts())

Output:

1245     1
5863     1
5682     1
1995     1
6978     1
1123     1
5659     1
34554    1
4539     1
6453     1
Name: Zipcode(s), dtype: int64