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Python Introduction to pandas Exploring pandas Exploration Methods

Posted by Mark Chesney
Mark Chesney
11,747 Points

users.csv

In this tutorial, how does this code read data out of users.csv? I'm quite curious, since I haven't even created the file! In other words, my question is this: why does this code work without me even saving a .csv file?

# Setup
import os
import pandas as pd

# We use os.path.join because Windows uses a back slash (\) to separate directories
#  while others use a forward slash (/)
users_file_name = os.path.join('data', 'users.csv')
users_file_name

# Open the file and print out the first 5 lines
with open(users_file_name) as lines:
    for _ in range(5):
        # The `file` object is an iterator, so just get the next line 
        print(next(lines))
Eric M
Eric M
11,545 Points
Eric M
Eric M
11,545 Points

Hi Mark,

I'm not sure what you mean here when you ask why this works. Where are you running the code and what output are you seeing?

If I run this in a directory that does not have a data subdirectory containing a users.csv it halts with FileNotFoundError: [Errno 2] No such file or directory: 'data\\users.csv'. If I run it with a csv with less than 5 lines (the loop range) it halts with a StopIteration error after printing the available lines.

Cheers,

Eric

1 Answer

Mark Chesney
Mark Chesney
11,747 Points

It just dawned on me... when I cloned the python-introducing-pandas repo, it contains a file subdirectory of data/users.csv, so that's why we're instructed to type this:

users_file_name = os.path.join('data', 'users.csv') users = pd.read_csv(users_file_name, index_col=0)

I'm slightly embarrassed for coming to such an obvious realization! :|

Mark Chesney
Mark Chesney
11,747 Points

So to be clear, yes, I did save the file when I cloned the repo for this course.