Python Import CSV to List

Importing .csv values as single list in Python

Try the following code

import csv

results = []
with open('test.csv', newline='') as inputfile:
    for row in csv.reader(inputfile):
        results.append(row[0])

print(results)

How do I read CSV files and put it in list with Python?

You are using this:

    customerID += item[0]

But that doesn't do what you think it does. customerID is a list and you're using the add operator on it, so Python tries to interpret item[0] as a list as well, which is a str, but can be considered a list of characters - so that's exactly what gets added.

Instead, use:

    customerID.append(item[0])

Or, if you prefer:

    customerID += [item[0]]

How to import a CSV data to a single list and append some values to the same?

Use chain.from_iterables from itertools:

import itertools

mylist = [['1', '2'], ['3', '4'], ['5', '6'], ['7', '8']]
mylist = list(itertools.chain.from_iterable(mylist))
mylist.append('hello')

>>> mylist
['1', '2', '3', '4', '5', '6', '7', '8', 'hello']

Writing a whole list into one row in csv python

First off, try not to name your variables the same as builtin types (list). This can break lots of stuff.
Edit: nvm I saw you edited your post.

You can just merge the list and variable into a string and then write that. You don't even need the csv writer.

myList = [a,b,c,d]
with open("CSVfile" + '.csv','w', encoding='utf-8') as f:
    line = '\t'.join([myVariable] + myList)
    f.write(line + '\n')

Importing CSV-file as list returns empty list

This is because a variable declared inside a function is only available inside that function and not in the global scope. In this case my suggestion would be to return the data from the function after you have finished reading the file. In other words something like this:

import csv

def read_file():
    with open ('filepath', 'r') as file:
        csv_reader = csv.reader(file, delimiter=';') 
        data=[] 
        for rad in csv_reader: 
            data.append(rad)

    return data

file_data = read_file()
print(file_data)

It is also possible to make the data variable inside the function global, however this is normally not recommended due to global variables quickly becoming hard to keep track of, it is much easier to see where data is coming from when it is returned from a function like this.

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