需要为 Panda 数据框打印一个新列

Question

I am using the following code to print ratio by applying a function, but am getting the following errors.

Code

import investpy
import pandas as pd
import numpy as np
import sys

def main(stock1_name, stock2_name):
    stock1 = investpy.get_stock_historical_data(stock=stock1_name,country='india', from_date='01/01/2020',to_date='08/03/2021')
    stock2 = investpy.get_stock_historical_data(stock=stock2_name,country='india', from_date='01/01/2020',to_date='08/03/2021')
    new_df = pd.merge(stock1, stock2, on='Date')
    new_df = new_df.drop(['Open_x', 'High_x', 'Low_x', 'Volume_x', 'Currency_x', 'Low_y','Volume_y', 'Currency_y', 'Open_y', 'High_y'], axis = 1)
    new_df['ratio'] = np.log10(new_df['Close_x']/new_df['Close_y'])
    return new_df
    x = main("IOC","HPCL")
print(x)

Error

NameError                                 Traceback (most recent call last)
<ipython-input-2-c17535375449> in <module>
     12     return new_df
     13     x = main("IOC","HPCL")
---> 14 print(x)

NameError: name 'x' is not defined

Answer 1

1. You are calling x = main("IOC","HPCL") inside the function main
2. This makes x defined only inside the scope of the function main
3. When you call print(x) outside function main the interpreter throws error, as it should, that x is not defined

Does this correction solve the issue:

import investpy
import pandas as pd
import numpy as np
import sys

def main(stock1_name, stock2_name):
    stock1 = investpy.get_stock_historical_data(stock=stock1_name,country='india', from_date='01/01/2020',to_date='08/03/2021')
    stock2 = investpy.get_stock_historical_data(stock=stock2_name,country='india', from_date='01/01/2020',to_date='08/03/2021')
    new_df = pd.merge(stock1, stock2, on='Date')
    new_df = new_df.drop(['Open_x', 'High_x', 'Low_x', 'Volume_x', 'Currency_x', 'Low_y','Volume_y', 'Currency_y', 'Open_y', 'High_y'], axis = 1)
    new_df['ratio'] = np.log10(new_df['Close_x']/new_df['Close_y'])
    return new_df

x = main("IOC","HPCL") # Edit moving this line outside the function main()
print(x)