如何将重复的行添加到 Pandas DF？

Question

I appreciate the help in advance!

The question may seem weird at first so let me illustrate what I am trying to accomplish:

I have this df of cities and abbreviations:

I need to add another column called 'Queries' and those queries are on a list as follows:

queries = ['Document Management','Document Imaging','Imaging Services']

The trick though is that I need to duplicate my df rows for each query in the list. For instance, for row 0 I have PHOENIX, AZ . I now need 3 rows saying PHOENIX, AZ, 'query[n]' .

Something that would look like this:

Of course I created that manually but I need to scale it for a large number of cities and a large list of queries.

This sounds simple but I've been trying for some hours now I don't see how to engineer any code for it. Again, thanks for the help!

Answer 1

Here is one way, using .explode() :

import pandas as pd

df = pd.DataFrame({'City_Name': ['Phoenix', 'Tucson', 'Mesa', 'Los Angeles'],
                   'State': ['AZ', 'AZ', 'AZ', 'CA']})

# 'Query' is a column of tuples
df['Query'] = [('Doc Mgmt', 'Imaging', 'Services')] * len(df.index)

# ... and explode 'unpacks' the tuples, putting one item on each line
df = df.explode('Query')
print(df)

     City_Name State     Query
0      Phoenix    AZ  Doc Mgmt
0      Phoenix    AZ   Imaging
0      Phoenix    AZ  Services
1       Tucson    AZ  Doc Mgmt
1       Tucson    AZ   Imaging
1       Tucson    AZ  Services
2         Mesa    AZ  Doc Mgmt
2         Mesa    AZ   Imaging
2         Mesa    AZ  Services
3  Los Angeles    CA  Doc Mgmt
3  Los Angeles    CA   Imaging
3  Los Angeles    CA  Services

Answer 2

new to python myself, but I would get around it by creating n (n=# of unique query values) identical data frames without "Query". Then for each of the data frame, create a new column with one of the "Query" values. Finally, stack all data frames together using append . A short example:

adf1 = pd.DataFrame([['city1','sate1'],['city2','state2']])
adf2 = adf1

adf1['query'] = 'doc management'
adf2['query'] = 'doc imaging'

df = adf1.append(adf2)

Another method if there are many types of queries. Creating a dummy column, say 'key', in both the original data frame and the query data frame, and merge the two on 'key'.

adf = pd.DataFrame([['city1','state1'],['city2','state2']])
q = pd.DataFrame([['doc management'],['doc imaging']])

adf['key'] = 'key'
q['key'] = 'key'

df = pd.merge(adf, q, on='key', how='outer')

More advanced users should have better ways. This is a temporary solution if you are in a hurry.

Answer 3

You should definitely go with jsmart's answer , but posting this as an exercise.

This can also be achieved by exporting the original cities/towns dataframe ( df ) to a list or records, manually duplicating each one for each query then reconstructing the final dataframe.

The entire thing can fit in a single line, and is even relatively readable if you can follow what's going on;)

pd.DataFrame([{**record, 'query': query}
               for query in queries
               for record in df.to_dict(orient='records')])