How to Create a List in Julia?

How to Create a List in Julia?

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  • Julia
  • 3 mins read

In Julia, a list is an ordered collection of elements. To create a list in Julia, you can use the [] syntax. Below are some examples:

Create a List in Julia Examples

julia> x = [1, 2, 3, 4]
4-element Array{Int64,1}:
 1
 2
 3
 4

In this example, the x variable is initialized to a list containing the numbers 1, 2, 3, and 4. You can access the elements of the list using indexing:

julia> x[1]
1

julia> x[2]
2

julia> x[3]
3

julia> x[4]
4

You can also add elements to a list using the push! function:

julia> push!(x, 5)
5-element Array{Int64,1}:
 1
 2
 3
 4
 5

julia> push!(x, 6)
6-element Array{Int64,1}:
 1
 2
 3
 4
 5
 6

In this example, the push! function is used to add the elements 5 and 6 to the end of the x list. The push! function modifies the list in place, so the original x list is updated with the new elements.

Create List using Comprehensions in Julia

You can also create lists using comprehensions, which provide a more concise syntax for creating lists from other collections. For example:

julia> x = [i^2 for i in 1:10]
10-element Array{Int64,1}:
  1
  4
  9
 16
 25
 36
 49
 64
 81
100

In this example, the x variable is initialized to a list of squares of the numbers from 1 to 10. The list comprehension is used to generate the elements of the list, where the i^2 expression is applied to each element i in the range 1:10. This generates a list of 10 elements, each of which is the square of the corresponding number in the range.

Create List using collect Function

You can also create lists using the collect function, which converts an iterator into a list. For example:

julia> x = collect(1:10)
10-element Array{Int64,1}:
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10

In this example, the collect function is used to create a list from the iterator 1:10, which generates the numbers from 1 to 10. This produces a list with 10 elements, each of which is a number from the iterator.

you can add elements to an empty list using the push! function. For example:

julia> x = []
0-element Array{Any,1}

julia> push!(x, 1)
1-element Array{Any,1}:
 1

julia> push!(x, 2)
2-element Array{Any,1}:
 1
 2

julia> push!(x, 3)
3-element Array{Any,1}:
 1
 2
 3

In this example, the x variable is initialized to an empty list using the [] syntax. Then, the push! function is used to add the elements 1, 2, and 3 to the list. The push! function modifies the list in place, so the original x list is updated with the new elements.

You can also create empty lists using the Array constructor and specify the type of elements that the list will contain. For example:

julia> x = Array{Int64}(undef, 0)
0-element Array{Int64,1}

julia> push!(x, 1)
1-element Array{Int64,1}:
 1

julia> push!(x, 2)
2-element Array{Int64,1}:
 1
 2

julia> push!(x, 3)
3-element Array{Int64,1}:
 1
 2
 3

In this example, the x variable is initialized to an empty list using the Array constructor with the undef keyword argument. This creates an empty list with the element type Int64. Then, the push! function is used to add the elements 1, 2, and 3 to the list. The push! function modifies the list in place, so the original x list is updated with the new elements.

Related:

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