list value validate in python

Question

Below input file has:

 info:pens-10-books-10,pens-10-books-20

I am reading this input file using python dictionary like below.

 d = {}
 with open('inputfile.txt') as f:
    for line in f:
    if ":" not in line:
        continue
    key, value = line.strip().split(":", 1)
    d[key] = value
for key, value in  d.iteritems():
    if key == 'info':
        goods = value.split(",")

Now I need help here to validate the input provided that is. goods declared as list so i need validate list values.

first octet must be alphabet, second octet must be number, third octet must be alphabet, fourth octet must be number. if contains more than 4 octets not valid input . Below are the examples

pens-10-books-10 --input valid
apples-1-cakes-10 --input valid
10-aplpes-10cakes --not valid input (as number contains at first octet)
pens-10-books-20-apples-10 -- not valid input (more than 4 octets)

Answer 1

You can use a regex which validates that your input matches your pattern:

>>> import re
>>> 
>>> def validate(string):
        if re.match(r'^[a-zA-Z]+\-\d+\-[a-zA-Z]+\-\d+$', string):
            return True
        return False

>>> validate('pens-10-books-10')
True
>>> validate('apples-1-cakes-10')
True
>>> validate('10-aplpes-10cakes')
False
>>> validate('pens-10-books-20-apples-10')
False
>>> 

To use this with your goods list, you can iterate over each element testing and displaying if it is valid:

>>> goods = ['pens-10-books-10', 'apples-1-cakes-10',
         '10-aplpes-10cakes', 'pens-10-books-20-apples-10']
>>> 
>>> for string in goods:
    print(validate(string))


True
True
False
False
>>>