Inconsistency in Python programming language?

[newbieAuggie2019]

Hi!

Well, this is a question that arose in some other threads that I was participating in, and I wanted to give it a bit more of a thought, and to ask for some insights from others.

The process of converting one data-type into another data-type is called casting, so in theory, with the str(), float(), and int() functions, we can transform a numeric value string into a float or into an integer, and in a similar way, a float into a string or an integer, or an integer into a string or a float.

So now, I'm going to show the inputs and outputs of some of these transformations:

Output:
>>> str(4)
'4'
>>> str('4')
'4'
>>> str(4.5)
'4.5'
>>> str('4.5')
'4.5'
>>> float(4)
4.0
>>> float('4')
4.0
>>> float(4.5)
4.5
>>> float('4.5')
4.5
>>> int(4)
4
>>> int('4')
4
>>> int(4.5)
4
>>> int('4.5')

Error:
Traceback (most recent call last):
  File "<pyshell#16>", line 1, in <module>
    int('4.5')
ValueError: invalid literal for int() with base 10: '4.5'

where we can see that:

1) a numeric value, naked or wrapped in quotes, in the format of a whole number or in the format of a float, can be transformed into a string with no problems.

2) a numeric value, naked or wrapped in quotes, in the format of a whole number or in the format of a float, can be transformed into a float with no problems.

3) a numeric value, naked or wrapped in quotes, in the format of a whole number or in the format of a float, can be transformed into an integer with no problems, EXCEPT WHEN IT'S A FLOAT WRAPPED IN QUOTES, THAT PRODUCES AN ERROR.


It seems that this is a contradiction on the casting of data types, or an inconsistency in Python programming language itself.

Do you have an explanation for that behaviour?
All insights are welcome!!!

All the best,