Continous Vs. discrete attributes

Question

Could anyone please clarify the difference between continuous and discrete attributes?

Thanks.

Answer 1

Hi

I will try to explain with an example:

Suppose your table in the database has a column which stores the temperature of the day or say a furnace. The values for that column come from a continuous domain of temperature values.

If the table has a column named gender. Then that is discrete in the sense that only two or maybe three values comprise its domain.

I hope this helps.

cheers

Answer 2

(It's been a long while since I did any pure maths, so take this with a pinch of salt.)

Speaking theoretically, continuous attributes come from an infinite set (i.e. real numbers, you can make them as large or small as you need). Discrete attributes come from a finite or countably infinite set (i.e. integers).

Another way of looking at it is that continuous attributes can have infinitesimally small differences between one value and the next, while discrete attributes always have some limit on the difference between one value and the next.

Practically spoken, continuous attributes would be a floating-point type, where discrete would be integers or characters.

Answer 3

Simon Righarts is right, except for his final conclusion.

Since computer memory is always finite, the set of representible values of any type is by definition also always finite too, and therefore in computer science there is no such thing as "continuous TYPES (which I think was what you were really asking about, not "continuous attributes"). Well, at least not in that part of computer science that gets applied anywhere in real life.

The classical floating-point type, encoded in 32 bits, has a maximum of 2^32 representible values. The classical floating-point type, encoded in 64 bits, has a maximum of 2^64 representible values. Non-representible values are plain useless and not worth considering. BigInteger types, which take as many bytes as are needed to hold a value, are limited to a maximum of 2^(8*computermemorysize) representible values. All of them are very much finite.