I have a huge list of Users_id that I want to concatenate. I know how to do it in excel but the file is much too large.
Users ID
101 101
102 101,102
103 101,102,103
104 101,102,103,104
Here is what I want to achieve. Here is what I have so far.
import pandas as pd
df = pd.read_csv('file.csv')
pd.concat = df['USER ID']=.astype(str)+','+df['USER ID']
This is an unusual operation since your input is numeric, while your output is a sequence of comma-separated strings. One solution is to use itertools.accumulate with f-strings (Python 3.6; PEP498):
import pandas as pd
from itertools import accumulate
df = pd.DataFrame({'Users': [101, 102, 103, 104]})
def joiner(x, y):
return f'{x},{y}'
df['Cumulative'] = list(accumulate(df['Users'].astype(str), func=joiner))
print(df)
Users Cumulative
0 101 101
1 102 101,102
2 103 101,102,103
3 104 101,102,103,104
I don't understand your code. If you want to concatenate all the user ids, you should iterate over the ID column and concatenate manually all the id. The following code should do so
id_column=df['ID']
all_ids=''
for id in id_column:
all_ids+=str(id)+','
All the IDs should be contained in variable all_ids.
','.join(df['ID'].astype(str)) is sufficient.