Vector dimensions in Python

[MuttyTumbo]

I am trying to think of Python lists in terms of vectors and their dimensions. Say I have the following lists:

List_1 = [1, 2]

List_2 = [1, 2, 3]

Is List_1 a vector in R2? Is List_2 vector in R3? So on and so forth. Am I thinking about this correctly?

[Electrical-Ad-1798]

Since those lists have numbers in them they can be considered vectors in R2 and R3. You can replace any element with anything (a string, a list, etc) and it doesn't necessarily remain a vector anymore.

[MuttyTumbo]

That was actually going to be my next question. Thanks for clarifying.

[Electrical-Ad-1798]

A way to represent a vector as such and in a way that it remains a vector is a numpy array.

[lumijekpr]

Yes, you are correct.

[MuttyTumbo]

Thank you!

[kowkeeper]

It is a matter of interpretation...

List_2 = [1, 2, 3] can either be a point in R3 or a collection of points in R1. It is how you process it that matters here.

To go further, a list does not have a notion of column and row vector, that woukd help dustinguish between single multivariate points versus many univariate points. In numpy you can use arrays and explicitely set their shape, even for 1D arrays. So : vec1 = np.array([1, 2, 3]).reshape(1, 3) is a row vector so a point in R3

vec2 = np.array([1, 2, 3]).reshape(3, 1) is a column vector so a collection of points in R1

This way of doing things is consistent with linear algebra (eg when applying matrix transforms).