68 – Split strings in two halves

Sometimes you’ll need to split the string in two halves. When that’s the case, you’ll want to use the method partition:

email = "rodrigo@mathspp.com"
user, at, domain = email.partition("@")

print(user)  # rodrigo
print(at)  # @
print(domain)  # mathspp.com

If the split fails, the first item of the 3-item tuple contains the full string and the two other items are the empty string:

email = "mathspp.com"
user, at, domain = email.partition("@")

print(user)  # mathspp.com
print(at == domain == "")  # True

This is better than using .split(..., maxsplit=1) because the return type makes it easier to check if the split was successful. With partition, it’s enough to check if the middle element is truthy or not:

email = input(" >>> ")
user, at, domain = email.partition("@")

if at:
    print("Split successful!")
else:
    print("Split was not successful!")

If the separator occurs 2+ times, partition splits on the first. Use rpartition to split on the last:

print("aaa oi bbb oi ccc".partition("oi"))
# ('aaa ', 'oi', ' bbb oi ccc')

print("aaa oi bbb oi ccc".rpartition("oi"))
# ('aaa oi bbb ', 'oi', ' ccc')