How can I repeat things (fall in the same category) using a comma

Question

Suppose I have many things that are fall in the same category. Suppose further that I need to use a bracket ( ) to add further information. Then, how can I repeat these things correctly?

The scatter plot (top), the density plot (middle), and the contour plot (bottom).

In this sentence, I tried to mention (with additional information) some plots. Scatter, density, and contour are all fall in the same category (plot). I feel that I should not repeat the pronoun the as I am talking about the same thing. In addition, I think I should not repeat the word plot for the same reason. I am not sure about this. However, by doing so, then I will have the following sentence, which I feel it is not correct.

The scatter (top), density (middle), and contour plots (bottom).

What I learned:

I learned that when I am talking about the same thing, then I do not need to repeat the same word or proposition. For example,

The type and color of the car are similar to mine.

So here, I do not need to repeat car and the preposition the.

Answer 1

The following is of course correct, and it is hard to imagine anyone complaining that it is verbose:

the scatter plot (top), the density plot (middle), and the contour plot (bottom)

The following simplified version (provided only for illustration) is also correct and easy to read:

the scatter, density, and contour plots

The version that combines them is unacceptable:

the scatter (top), density (middle), and contour plots (bottom)

The reason is that (bottom) modifies the word "plots," not "contour." It therefore applies to all three items in the series, which is not the intended meaning.

But the following, while correct, is not much better:

the scatter (top), density (middle), and contour (bottom) plots

This phrase asks the reader to do a lot of "algebra" to understand the meaning. I would be unsurprised to read it in an academic paper, but I would not recommend it.

Answer 2

I think removing the article "the" (that's not a preposition by the way) is fine. I also do that too.

As for the case of removing the word plot, the two examples you have given are somewhat different cases. In your second example, the word "car" is a possessive noun. You could also rephrase this into "the car's color and type" and it would still hold the same meaning.

Meanwhile, in the first sentence, "scatter", "density", "contour" are adjectives or descriptive words. For normal adjectives, I'd say you can do so. For example, "My dad owns those red, white, and black cars." You don't need to say "red cars, white cars, and black cars".

For your case, I don't think you should. Keep in mind that I'm not an expert in English, so I may be wrong. I'm just saying what I would do. In my example, when you combine the adjective (red/white/black) and the noun (car), it would pertain to a car that is red, a car that is white, and a car that is black (or cars, whatever). It was fine because the adjectives can stand on its own.

But scatter plots, density plots, and contour plots don't work the same way. You can't say that scatter plots are plots that are scattered. Adding them together is not simply a representation of the two words separately. For me, it just seems a bit off if you condense it into "scatter, density, and contour plots". To somewhat remove the feeling of redundancy, you can write "the scatter plot on top, the density plot in the middle, and the contour plot at the bottom".