EmptyDataError: No columns to parse from file. (Generate files with "for" in Python) - python-3.x

Question

The following code obtains specific data from an internet financial portal (Morningstar). I obtain data from different companies, in this case from Dutch companies. Each one is represented by a ticker.
import pandas as pd
import numpy as np
def financials_download(ticker,report,frequency):
if frequency == "A" or frequency == "a":
frequency = "12"
elif frequency == "Q" or frequency == "q":
frequency = "3"
url = 'http://financials.morningstar.com/ajax/ReportProcess4CSV.html?&t='+ticker+'&region=usa&culture=en-US&cur=USD&reportType='+report+'&period='+frequency+'&dataType=R&order=desc&columnYear=5&rounding=3&view=raw&r=640081&denominatorView=raw&number=3'
df = pd.read_csv(url, skiprows=1, index_col=0)
return df
def ratios_download(ticker):
url = 'http://financials.morningstar.com/ajax/exportKR2CSV.html?&callback=?&t='+ticker+'&region=usa&culture=en-US&cur=USD&order=desc'
df = pd.read_csv(url, skiprows=2, index_col=0)
return df
holland=("AALBF","ABN","AEGOF", "AHODF", "AKZO","ALLVF","AMSYF","ASML","KKWFF","KDSKF","GLPG","GTOFF","HINKF","INGVF","KPN","NN","LIGHT","RANJF","RDLSF","RDS.A","SBFFF", "UNBLF", "UNLVF", "VOPKF", "WOLTF")
def finance(country):
for ticker in country:
frequency = "a"
df1 = financials_download(ticker,'bs',frequency)
df2 = financials_download(ticker,'is',frequency)
df3 = ratios_download(ticker)
d1 = df1.loc['Total assets']
if np.any("EBITDA" in df2.index) == True:
d2 = df2.loc["EBITDA"]
else:
d2 = None
if np.any("Revenue USD Mil" in df3.index) == True:
d3 = df3.loc["Revenue USD Mil"]
else:
d3 = df3.loc["Revenue EUR Mil"]
d4 = df3.loc["Operating Margin %"]
d5 = df3.loc["Return on Assets %"]
d6 = df3.loc["Return on Equity %"]
d7 = df3.loc["EBT Margin"]
d8 = df3.loc["Net Margin %"]
d9 = df3.loc["Free Cash Flow/Sales %"]
if d2 is not None:
d1=d1.to_frame().T
d2=d2.to_frame().T
d3=d3.to_frame().T
d4=d4.to_frame().T
d5=d5.to_frame().T
d6=d6.to_frame().T
d7=d7.to_frame().T
d8=d8.to_frame().T
d9=d9.to_frame().T
df_new=pd.concat([d1,d2,d3,d4,d5,d6,d7,d8,d9])
else:
d1=d1.to_frame().T
d3=d3.to_frame().T
d4=d4.to_frame().T
d5=d5.to_frame().T
d6=d6.to_frame().T
d7=d7.to_frame().T
d8=d8.to_frame().T
d9=d9.to_frame().T
df_new=pd.concat([d1,d3,d4,d5,d6,d7,d8,d9])
df_new.to_csv(ticker+'.csv')
The problem is that when I use a for loop so that it goes through all the tickers of the variable holland and generates a csv document for each of them, it returns the following error:
File "pandas/_libs/parsers.pyx", line 565, in
pandas._libs.parsers.TextReader.__cinit__ (pandas\_libs\parsers.c:6260)
EmptyDataError: No columns to parse from file
On the other hand, it runs without error, if I just select one company ticker after the other.
I'd really appreciate it if you could help me.

Answer 1

When you run your script several times, it fails on different tickers and different calls. This gives you an indication that the problem is not associated with a specific ticker, but rather that the call from the csv reader doesn't return a value that can be read into the data frame. You can address this problem, by using Python's error handling routines, e.g. for your financials_download function:
df = ""
i = 0
#some data in df?
while len(df) == 0:
#try to download data and load them into df
try:
df = pd.read_csv(url, skiprows=1, index_col=0)
#not successful? Count failed attempts
except:
i += 1
print("Trial", i, "failed")
#five attempts failed? Unlikely that this server will respond
if i == 5:
print("ticker", ticker, ": server is down")
break
#print("downloaded", ticker)
#print("financial download data frame:")
#print(df)
This tries five times to retrieve the data from the ticker and if this fails, it prints a message that it was not successful. But now you have to deal with this situation in your main program and adjust it, because some of the data frames are empty.
I would like to point you for this kind of basic debugging to a blog post.