casregnum

Python class to manage, check and sort CAS Registry Numbers® (CAS RN®).

Description

casregnum is a Python class to manage, check, and sort CAS Registry Numbers® (CAS RN®) by the Chemical Abstracts Service. Check their official FAQ website for more information on CAS numbers.

How to install and uninstall

casregnum can be installed from the Python Package Index (PyPI) repository by calling

pip install casregnum

or

uv add casregnum

In order to uninstall casregnum from your local environment use

pip uninstall casregnum

or

uv remove casregnum

How to use

casregnum provides the CAS class for creating a CAS Registry Number® instance:

from casregnum import CAS

substance = CAS(cas_rn)

Note that cas_rn can either be an integer or a string. If you provide an integer, the CAS class will take care of formatting the CAS RN® for you. If you provide a string, it needs to comply with the CAS number formatting rules, i. e. 2-7 digits dash two digits dash single check digit (_____00-00-0).

The CAS class offers the following three properties:

.cas_string   # CAS number formatted as a string
.cas_integer  # CAS number as an integer
.check_digit  # check digit of the CAS number

Examples:

from casregnum import CAS

caffeine = CAS(58_08_2)
theine = CAS("58-08-2")
l_lacticacid = CAS(79_33_4)
d_lacticacid = CAS(10326_41_7)
octanes = [
    CAS(111_65_9), CAS(592_27_8), CAS(589_81_1), CAS(589_53_7), CAS( 590_73_8), CAS(584_94_1),
    CAS(589_43_5), CAS(592_13_2), CAS(563_16_6), CAS(583_48_2), CAS( 619_99_8), CAS(564_02_3),
    CAS(540_84_1), CAS(560_21_4), CAS(565_75_3), CAS(609_26_7), CAS(1067_08_9), CAS(594_82_1),
]

print(f"str: {caffeine}")
print(f"int: {theine.cas_integer}")
print(f"check digit: {caffeine.check_digit}")
print(f"{caffeine} == {theine}: {caffeine == theine}")
print(f"{caffeine} > {theine}: {caffeine > theine}")
print(f"{l_lacticacid} > {d_lacticacid}: {l_lacticacid > d_lacticacid}")
print(f"{l_lacticacid} < {d_lacticacid}: {l_lacticacid < d_lacticacid}")

for i, isomer in enumerate(sorted(octanes), start=1):
    print(f"{isomer:>9}", end=", ")
    if i % 6 == 0:
        print()

This will generate the following output:

str: 58-08-2
int: 58082
check digit: 2
58-08-2 == 58-08-2: True
58-08-2 > 58-08-2: False
79-33-4 > 10326-41-7: False
79-33-4 < 10326-41-7: True
111-65-9,  540-84-1,  560-21-4,  563-16-6,  564-02-3,  565-75-3,
583-48-2,  584-94-1,  589-43-5,  589-53-7,  589-81-1,  590-73-8,
592-13-2,  592-27-8,  594-82-1,  609-26-7,  619-99-8, 1067-08-9,