When working with multi-dimensional arrays in Julia, it is often necessary to convert between linear indices and subscripts. In earlier versions of Julia, the functions ind2sub and sub2ind were commonly used for this purpose. However, in Julia 0.7 and later versions, these functions have been deprecated and replaced with the CartesianIndices type and the LinearIndices type.
Option 1: Using CartesianIndices
The CartesianIndices type provides a convenient way to convert between linear indices and subscripts. To convert a linear index to subscripts, you can use the CartesianIndices constructor:
A = reshape(1:12, (3, 4))
linear_index = 7
subscripts = CartesianIndices(A)[linear_index]
To convert subscripts to a linear index, you can use the CartesianIndex function:
subscripts = (2, 3)
linear_index = CartesianIndex(subscripts)
Option 2: Using LinearIndices
The LinearIndices type provides an alternative way to convert between linear indices and subscripts. To convert a linear index to subscripts, you can use the LinearIndices function:
A = reshape(1:12, (3, 4))
linear_index = 7
subscripts = LinearIndices(A)[linear_index]
To convert subscripts to a linear index, you can use the sub2ind function:
subscripts = (2, 3)
linear_index = sub2ind(size(A), subscripts...)
Option 3: Using LinearIndices with CartesianIndex
Another option is to combine the LinearIndices type with the CartesianIndex type. This allows you to convert between linear indices and subscripts using the CartesianIndex constructor and the LinearIndices function:
A = reshape(1:12, (3, 4))
linear_index = 7
subscripts = CartesianIndex(LinearIndices(A)[linear_index])
subscripts = (2, 3)
linear_index = LinearIndices(A)[CartesianIndex(subscripts)]
After considering the three options, it is recommended to use Option 1: Using CartesianIndices. This option provides a more intuitive and concise way to convert between linear indices and subscripts. It also aligns with the deprecation of the ind2sub and sub2ind functions in Julia 0.7 and later versions.
