Select some particular elements to a set

In summary, to present the set $A$ in math language, we can use the notation $A = \{i : i=1,2,3,...,N \text{ and } a_i \text{ is among the } M \text{ largest values of } a_i \}$.
  • #1
baiyang11
9
0
What I am asking is not a math "problem" but something about presenting the problem in math language.

Assume $0<a_{i}<1, i=1,2,3,...,N$ and $a_{i} \neq a_{j}$, I want to have a set $A$ which contains the $M$ indices with the top $M$ values of $a_{i}$.

For example, we have $a_{1}=0.2, a_{2}=0.6, a_{3}=0.5, a_{4}=0.7$ and $a_{5}=0.1$, and assume $M=3$. Then $I=\{2,3,4\}$.

But how to present $A$ in math language given all $a_{i}$ and $M$?

Thank you for your help.
 
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  • #2
The set $A$ can be expressed as:$$A = \{i : i=1,2,3,...,N \text{ and } a_i \text{ is among the } M \text{ largest values of } a_i \}$$
 

FAQ: Select some particular elements to a set

1. How do you select elements to add to a set?

To select elements to add to a set, you can use the "add" method or the "update" method. The "add" method adds a single element to the set, while the "update" method adds multiple elements at once.

2. Can you select all elements in a set at once?

Yes, you can select all elements in a set using the "update" method. This method takes in an iterable object such as a list or tuple, and adds all the elements in the object to the set.

3. How do you remove elements from a set?

To remove elements from a set, you can use the "remove" method or the "discard" method. The "remove" method removes a specific element from the set, while the "discard" method removes an element if it is present in the set.

4. Is it possible to select elements based on a specific criteria?

Yes, it is possible to select elements based on a specific criteria by using list comprehensions. List comprehensions allow you to filter elements from a set based on a condition, and then add them to a new set.

5. How do you select elements from a set in a specific order?

Sets are inherently unordered collections, so you cannot select elements from a set in a specific order. If you need to maintain a specific order, consider using a different data structure such as a list or tuple.

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