Let vec = [(“A”, “B”), (“A”, “C”), (“A”, “D”), (“B”, “C”), (“B”, “D”)] be a vector.

I want to count the number of appearance of each element at each step in the for loop.

```
function count_occurrences(vec)
vect = []
nb_appear_A = 0
nb_appear_B = 0
nb_appear_C = 0
nb_appear_D = 0
for v in vec
v1, v2 = v
if v1 == "A"
nb_appear_A += 1
end
if v2 == "A"
nb_appear_A += 1
end
if v2 == "B"
nb_appear_B += 1
end
if v1 == "B"
nb_appear_B += 1
end
if v1 == "C"
nb_appear_C += 1
end
if v2 == "C"
nb_appear_C += 1
end
if v1 == "D"
nb_appear_D += 1
end
if v2 == "D"
nb_appear_D += 1
end
# I check for each pairs and push them onto vect
if v1 == "A" && v2 == "B"
push!(vect, (nb_appear_A, nb_appear_B))
elseif v1 == "A" && v2 == "C"
push!(vect, (nb_appear_A, nb_appear_C))
elseif v1 == "A" && v2 == "D"
push!(vect, (nb_appear_A, nb_appear_D))
elseif v1 == "B" && v2 == "C"
push!(vect, (nb_appear_B, nb_appear_C))
elseif v1 == "B" && v2 == "D"
push!(vect, (nb_appear_B, nb_appear_D))
elseif v1 == "C" && v2 == "D"
push!(vect, (nb_appear_C, nb_appear_D))
end
end
return vect
end
count_occurrences(vec)
5-element Vector{Any}:
(1, 1)
(2, 1)
(3, 1)
(2, 2)
(3, 2)
```

This code works, but I would like to apply it for a different vector, say `vec = [("A", "B"), ("A", "C"), ("A", "D"), ("B", "C"), ("R", "E"),...]`

.