Enumerate is very helpful when you want the index and the value when looping over list, tuple, dictionary, etc. Enumerate comes with an automatic counter/index to each of the items present in the list. The first index value will start from 0.
What is Python Enumerate? Python Enumerate () is a buit-in function available with the Python library. It takes the given input as a collection or tuples and returns it as an enumerate object. The Python Enumerate () command adds a counter to each item of the iterable object and returns an enumerate object as an output string.
In Python, a dictionary is listed in curly brackets, inside these curly brackets, the values are declared. Each element is a key/value pair and separated by commas. You can use a dictionary inside a enumerate () and see the output.
Advantages of using Enumerate. Here, are pros/benefits of using Enumerate in Python: Enumerate allows you to loop through a list, tuple, dictionary, string, and gives the values along with the index. To get index value using for-loop, you can make use of list.index (n). However, list.index (n) is very expensive as it will traverse ...
Parameters. Iterable: an object that can be looped. StartIndex: (optional) The count will start with the value given in the startIndex for the first item in the loop and increment it for the nextitem till it reaches the end of the loop. However, If startIndex is not specified, the count will start from 0.
Enumerating a Tuple. In the below example, you can use a tuple inside an enumerate. You can also use a startIndex, and the key to each item will start from the startIndexgiven. By default, the startIndex is 0. There, hence you see key as 0 for items A and 1 for B and so on.
In Python, the string is an array, and hence you can loop over it. If you pass a string to enumerate (), the output will show you the index and value for each character of the string.
The results of classical angular momentum provide a clear physical modelfor representation of orbital and spin angular momentum in terms of the vectormodel. Let us now consider the new features that are introduced by the laws ofquantum mechanics which spin angular momentum (both electronic andnuclear) must obey.
Classical angular momentum refers to the rotation motion of of an objectaround a fixed point or about a fixed axis. The two most important models ofangular momentum for chemistry are (1) a particle constrained to move in acircular path with a fixed radius about a point (Figure 4, left) and (2) a sphericalbody rotating about a fixed axis that passes through a point at the center of thesphere (Figure 4, right). These two simple models capture the essence of theorigin of electron orbital angular momentum and to electron spin angularmomentum.
The peculiar square root relationship of eq. 3a is embedded in theremarkable trigonometric features of all vectors. The triangular relationshipamong vectors in 2 dimensions is shown in Figure 5. From the familarPythagorean theorem, Eqs. 5 a and 5 b provide a relationship between the square
According to the laws of quantum mechanics, an electron or group ofelectrons can be characterized completely by certain quantum numbers. Whenwe say that an electron or a proton has a spin of 1/2 we usually are referring tothe electron's spin quantum number, S, rather than the magnitude of the spinangular momentum. However, when we say we are dealing with any particlewith spin of 1/2 we also mean that the particle has an inherent, irremovableangular momentum of 1/2 which can be measured in an experiment. (Thequantum number for total spin will be represented by the plain type and carewill be taken to distinguish this unitless quantity from the magnitude of the spin,which has the units of angular momentum). For electron spin there are only twopertintent quantum numbers: S, the quantum number associted with the lengthof the total spin and MS the quantum number assoicated with the orientation ofthe total spin relative to the z axis. The relationship between the quantumnumber, S (unitless), and the magnitude of the total spin angular momentum S