Extracting strings in specified format in python

Question

In python Im writing code to extract string from alphanumeric characters. The code should extract only string and print in the following format.

Input should be given in the form of IND1234AUS1234 (i.e Characters must be separated by few digits)

For the above input python code should extract string IND and AUS and print as IND to AUS

Input must not given in any other formats other than mentioned above and if given in wrong format, code should print invalid input. (example of wrong formats of inputs are 1234INDAUS, IND1234, 123IND123AUS, INDAUS1234)

Below is the code i have tried. It extracts string but I don't know how to seperate and print as IND to AUS

My program prints only INDAUS

test_string  = input()
only_alpha = ""
for char in test_string:
    if char.isalpha():
      only_alpha += char
print(only_alpha)

Please help me with the code. I don't know to write code for validating invalid inputs as i mentioned above.

Is there any constraint on the number of letters and digits ? — azro
– azro, Commented May 3, 2020 at 14:28
No. There are no constraints on number of letters and digits. Its letters followed by digits and again letters followed by digits. — Ashok Kumar
– Ashok Kumar, Commented May 3, 2020 at 15:12
Preferably letters of atleast 2 or 3 characters and atleast one digit followed after letters like IND12AUS1234. — Ashok Kumar
– Ashok Kumar, Commented May 3, 2020 at 15:17

azro · Accepted Answer · 2020-05-04 07:35:22Z

2

You whould use a regex to

validate the content [A-Z]+\d+[A-Z]+\d+ : upper with digits twice
retrieve the uppercase content at the same time ([A-Z]+)\d+([A-Z]+)\d+ parenthesis to make captuting group anr get content with .groups()

def extract(value):
    m = re.search(r"([A-Z]+)\d+([A-Z]+)\d+", value)
    if m:
        return " to ".join(m.groups())
    return "Invalid Input"

Testing

value = "IND1234AUS1234 "
res = extract(value)
print(res)  # IND to AUS

value = "INDAUS1234 "
res = extract(value)  # Invalid Input
print(res)

A regex that checks the length of each part would be

"([A-Z]{2,5})\d{1,5}([A-Z]{2,5})\d{1,5}"

edited May 4, 2020 at 7:35

answered May 3, 2020 at 14:25

azro

54.2k9 gold badges38 silver badges75 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Ashok Kumar Over a year ago

@azro For invalid input just print Invalid input.

azro Over a year ago

@AshokKumar Sorry to tell you that but this is very basic code, don't call me genius ;) Also you have to understand it, understand why it return the good string a in case, and why 'invalid' in the other case. Also I've edit to put at the end the regex that check the length of each part

score 0 · Accepted Answer · 2020-05-03 14:28:28Z

0

This looks like a perfect way to use regex:

def validate(a):
    match = re.match("([A-Z]+)[0-9]+([A-Z]+)[0-9]+", a)
    if not match:
        raise ValueError()
    else:
        return match[1] + " to " + match[2]

>>> validate("IND1234AUS1234")
"IND to AUS"
>>> validate("USD1234EUR1234")
"USD to EUR"
>>> validate("123IND123AUS")
Traceback (most recent call last):
  File "<pyshell#23>", line 1, in <module>
    validate("123IND123AUS")
  File "<pyshell#20>", line 4, in validate
    raise ValueError()
  File "<string>", line None
SyntaxError: <no detail available>

Quick explanation: "([A-Z]+)[0-9]+([A-Z]+)[0-9]+"

([A-Z]+): One or more A-Z characters, in parenthesis so we can index them later
[0-9]+: One or more digits

edited May 3, 2020 at 14:28

answered May 3, 2020 at 14:27

user6597761

2 Comments

Ch3steR Over a year ago

You should raise ValueError instead of SyntaxError

user6597761 Over a year ago

@Ch3steR Now changed

Collectives™ on Stack Overflow

Extracting strings in specified format in python

2 Answers 2

2 Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related