John Hanlon John Hanlon - 1 year ago 754
Python Question

Trying to iterate and join Pandas DFs: AttributeError: 'Series' object has no attribute 'join'

I'm looking to pull the historical data for ~200 securities in a given index. I import the list of securities from a csv file then iterate over them to pull their respective data from the quandl api. That dataframe for each security has 12 columns, so I create a new column with the name of the security and the Adjusted Close value, so I can later identify the series.

I'm receiving an error when I try to join all the new columns into an empty dataframe. I receive an attribute error:

Print output data
AttributeError: 'Series' object has no attribute 'join'

Below is the code I have used to arrive here thus far.

Import the modules necessary for analysis

import quandl
import pandas as pd
import numpy as np

Set file pathes and API keys

ticker_path = ''
auth_key = ''

Pull a list of tickers in the IGM ETF

def ticker_list():
df = pd.read_csv('{}IGM Tickers.csv'.format(ticker_path))
# print(df['Ticker'])
return df['Ticker']

Pull the historical prices for the securities within Ticker List

def grab_constituent_data():
tickers = ticker_list()
main_df = pd.DataFrame()

for abbv in tickers:
query = 'EOD/{}'.format(str(abbv))
df = quandl.get(query, authtoken=auth_key)
print('Competed the query for {}'.format(query))

df['{} Adj_Close'.format(str(abbv))] = df['Adj_Close'].copy()
df = df['{} Adj_Close'.format(str(abbv))]
print('Completed the column adjustment for {}'.format(str(abbv)))

if main_df.empty:
main_df = df
main_df = main_df.join(df)


Answer Source

It seems that in your line

df = df['{} Adj_Close'.format(str(abbv))]

you're getting a Serie and not a Dataframe. If you want to convert your serie to a dataframe, you can use the function to_frame() like:

df = df['{} Adj_Close'.format(str(abbv))].to_frame()

I didn't check if your code might be more simple, but this should fix your issue.

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