# Why are ordered lists considered one dimensional?

At Uni I am currently taking data visualization as a course. While reading thru the script I stumbled upon two examples for one dimensional data. Example one: Bus stops with their name and order (current -> next bus stop). Example two: A list of values (not a set!)(the type of value does not matter for the sake of simplicity).

Now I am wondering how an ordered list can be two dimensional. To me it looks like two dimensional data. The first dimension being the index, the second one being the value. For the first example the two dimensions could be the station name and the next stations name.

Since v(t) is considered as two dimensional data (according to my Prof) I am wondering why value(index) us not two dimensional data.

Representation wise I can understand why the data can be represented one dimensional, since they can be represented in a straight line. But feature wise I don't understand how value(index) and v(t) are different.

Please enlighten my mind since the prof only told me to stick to the script...

The specific ordering is only metadata as it is not explicitly in the data itself, and the index doesn't always represent order.

If you have an additional row with the order in then it would be two dimensional. But, for example, you wouldn't be able to distinguish between ascending and descending order by looking at the index itself.

v(t) is velocity by time

data[index] is data point by location in a data object (rather than known order).

Perhaps you could argue that the index is a second dimension, but consider this, how would you represent 1D data in a computer otherwise?

• Please accept the answer if it resolved your issue or let me know if something is unclear
– WBM
Apr 29, 2021 at 11:21