Have an index error I don't know how to correct
<p>I found this code elsewhere on the site, but for some reason I keep getting the same error message:</p>

<pre><code>products[row[0]] = [row[1], row[2], row[3]]
IndexError: list index out of range.
</code></pre>

<p>I am unsure how to correct this, any help is appreciated, thanks. </p>

<p>This is the code:</p>

<pre><code>MAX_FIELD_LEN = 8

def main():
    products = {}
    product_location  = {}
    location = 0
    # This is the file directory being made.
    with open('stockfile.txt', 'r+') as f:
        # This is my file being opened.

        for line in f:
            # keep track of each products location in file  to overwrite with New_Stock
            product_location[line.split(',')[0]] = location
            location += len(line)
            # Need to strip to eliminate end of line character
            line = line[:-1]
            # This gets rid of the character which shows and end of line '\n'
            row = line.split(',')
            # The row is split by the comma
            products[row[0]] = [row[1], row[2], row[3]]
            # The products are equal to row 1 and row 2 and row 3. The GTIN is going to take the values of the product and price so GTIN 12345678 is going to correspond to Fridge and 1.

        print(products)
        total = 0

        while True:
            GTIN = input('Please input GTIN: ')
            # To terminate user input, they just need to press ENTER
            if GTIN == "":
                break
            if (GTIN not in products):
                print('Sorry your code was invalid, try again:')
                break

            row = products[GTIN]
            description, value, stock = row
            print('Stock data: ')
            print('GTIN \t\tDesc. \t\tStock \t\tValue')
            print(GTIN,'\t',description,'\t', stock, '\t', value)

            quantity = input('Please also input your quantity required: ')
            row[2] = str(int(stock) - int(quantity))
            product_total = int(quantity) * int(value)
            for i in range(len(row)):  
                row[i]  = row[i].rjust(MAX_FIELD_LEN)
            New_Stock = GTIN.rjust(MAX_FIELD_LEN) + ',' + ','.join(row) + '\n'
            #print(New_Stock, len(New_Stock))
            f.seek(product_location[GTIN])
            f.write(New_Stock)
            print('You bought: {0} {1} \nCost: {2}'.format(GTIN, description, product_total))

            total = total + product_total
        f.close()
        print('Total of the order is Â£%s' % total)

main()
</code></pre>

<p>Please check your input file 'stockfile.txt', at least one line of your file don't have 3 or more ",". Or you have some blank lines between your data.</p>

python indexoutofboundsexception