CODEWITHSUNDEEP
pythonpython-3.xpandasdataframe
sindhuja
sindhuja

Reputation: 175

creating list from dataframe

I am a newbie to python. I am trying iterate over rows of individual columns of a dataframe in python. I am trying to create an adjacency list using the first two columns of the dataframe taken from csv data (which has 3 columns).

The following is the code to iterate over the dataframe and create a dictionary for adjacency list:

df1 = pd.read_csv('person_knows_person_0_0_sample.csv', sep=',', index_col=False, skiprows=1) 

src_list = list(df1.iloc[:, 0:1])
tgt_list = list(df1.iloc[:, 1:2])
    adj_list = {}

    for src in src_list:
        for tgt in tgt_list:
            adj_list[src] = tgt


    print(src_list) 
    print(tgt_list)
    print(adj_list)

and the following is the output I am getting:

['933']
['4139']
{'933': '4139'}

I see that I am not getting the entire list when I use the list() constructor. Hence I am not able to loop over the entire data.

Could anyone tell me where I am going wrong?

To summarize, Here is the input data: 

A,B,C
933,4139,20100313073721718
933,6597069777240,20100920094243187
933,10995116284808,20110102064341955
933,32985348833579,20120907011130195
933,32985348838375,20120717080449463
1129,1242,20100202163844119
1129,2199023262543,20100331220757321
1129,6597069771886,20100724111548162
1129,6597069776731,20100804033836982

the output that I am expecting: 

933: [4139,6597069777240, 10995116284808, 32985348833579, 32985348838375]
1129: [1242, 2199023262543, 6597069771886, 6597069776731]

Upvotes: 2

Views: 90

Answers (1)

jezrael
jezrael

Reputation: 862641

Use groupby and create Series of lists and then to_dict:

#selecting by columns names
d = df1.groupby('A')['B'].apply(list).to_dict()

#seelcting columns by positions
d = df1.iloc[:, 1].groupby(df1.iloc[:, 0]).apply(list).to_dict()

print (d)
{933: [4139, 6597069777240, 10995116284808, 32985348833579, 32985348838375],
 1129: [1242, 2199023262543, 6597069771886, 6597069776731]}

Upvotes: 2

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