Adding A Label Column To A Dataframe

I have a data frame where I get the stocks data (OHLC) and date as index. However, the ticker name is not shown there. So, data looks something like this : open

Solution 1:

I'm not familiar with the iexfinance library. But Let's say you have a magic function get_data_from_ticker which, as the name implies, gets data given a ticker input, possibly as a pd.DataFrame object.

Given a list tickers, your current process may look like:

dfs = []
for ticker in tickers:
    data = get_data_from_ticker(ticker)
    dfs.append(data)
df = pd.concat(dfs)

This isn't particularly useful if the ticker information is not stored in your dataframe. So you can use pd.DataFrame.assign to add a series accordingly:

dfs = []
for ticker in tickers:
    data = get_data_from_ticker(ticker)
    dfs.append(data.assign(ticker=ticker))
df = pd.concat(dfs)

Finally, you can make this a more efficient by using a list comprehension:

dfs = [get_data_from_ticker(ticker).assign(ticker=ticker) for ticker in tickers]

df = pd.concat(dfs)