Mathematica MyList[[ 1, 3, 2 ]] using ind = {1, 3, 2}

[Swamp Thing]

Given a list of indices ind = {1, 3, 2} , is there a shortcut to this? :--

MyList[[ ind[[1]], ind[[2]], ind[[3]] ]]

 

[jedishrfu]

Do you mean like list comprehensions? They are one-liner list initializations and can use list to initialize lists as shown in this tutorial:

https://www.geeksforgeeks.org/python-list-comprehension/

 

[Swamp Thing]

Not list comprehension, but something much simpler.

It's about Mathematica, indexing into a list.

Normally, you do MyList [[ m, n, o ]] when the indices m, n, o are available in variables. But if m, n, o are contained in a list like lst={1,3,2} then is there a more compact alternative to the code in my OP?

 

[Wrichik Basu]

Normally, you do MyList [[ m, n, o ]] when the indices m, n, o are available in variables. But if m, n, o are contained in a list like lst={1,3,2} then is there a more compact alternative to the code in my OP?

In MATLAB, syntax like arr(ind) is accepted, where ind is an array of indexes of arr.

>> arr1 = [5 9 10 7 6 ];
>> ind = [1 3 2];
>> arr1(ind)

ans =

     5    10     9

Have you tried something like MyList [[ lst ]], a rough equivalent of the above MATLAB code?

 

[DrClaude]

Given a list of indices ind = {1, 3, 2} , is there a shortcut to this? :--

MyList[[ ind[[1]], ind[[2]], ind[[3]] ]]

MyList[[ Sequence @@ ind ]]

 

[Swamp Thing]

Have you tried something like MyList [[ lst ]], a rough equivalent of the above MATLAB code?

If MyList is multidimensional, the above will pull out rows 1, 3 and 2. What I'm looking for is to pull out the single element MyList[[1, 3, 2]].

MyList[[ Sequence @@ ind ]]

Thank you.
I'm now experimenting with @@, which I am meeting here for the first time.
What is going on here:

Sqrt @@ Sin[2]

Output:
$\sqrt{2}$

Sqrt @@ Sin[2.0001]

Output:
0.909256

 

[DrClaude]

Try FullForm on what you put right of @@.

FullForm[Sin[2]]

FullForm[Sin[2.0001]]