# Convert a Vector of Vectors to an Array

It’s often the case in physics that one deals with a vector (i.e. a 1d array or list), where each entry is also a vector. Here’s some code which takes a list of vectors and converts them into an array in Julia.

The code is also available in a public gist at https://gist.github.com/paulnakroshis/ca3ce8de9520c389e3144b69ba30b07b

Here is the code (tested in Julia 1.8.5)

``````"""
# Convert a vector of vectors to an array
This function assumes that each vector is the same length;
i.e.
v1 = [ [1,2], [2,3], [5,6] ] # this is fine
v2 = [ [1,2,8], [2,3], [5,6] ] # this is not fine

Example of usage:
```
vv = [[1,2,3], [4,5,6], [7,8,9],[12,13,14]]
println("num components in each vector = ", length(vv))
println("num of vectors = ", length(vv))
vecvec_to_array(vv)
```
"""
function vecvec_to_array(vecvec)
dim1 = length(vecvec)
dim2 = length(vecvec)
my_array = zeros(Int64, dim1, dim2)
for i in 1:dim1
for j in 1:dim2
my_array[i,j] = vecvec[i][j]
end
end
return my_array
end`````` 