How to add new element to array?

[g2m.agent]

Suppose I want to divide a value equally, and then add these values together and store them in an array. For example, 90 is divided into 3 equal parts, and the cumulative result is [30, 60, 90]. I can do this in Python:

v = 90 # value
max = 3 # max_iterations
i = 1 # current_index
step = i/max
degrees = [] # output array
while i <= max:
    degree = step*v*i
    degrees.append(degree)
    i += 1
print(degrees)
# Result: [30.0, 60.0, 90.0] #

 But how to do this in bifrost?

My graph is not working...

outside:

inside

I got warning:

"output", Warnings: - array Warning: while compiling top level compound "bifrostGraphShape1", around the port 'bifrostGraphShape1::iterate.array': no promotion exists from a value of type 'array<float>' to a value of type 'float'

why?

[mjcg91 · Accepted solution]

Ports states has to be the same data type. In this case you want to append the computed value on an empty array on which you append a value at each iterations.

[g2m.agent]

It works. But I don't understand how this iteration works. why doesn't "build_array" become a 2d array? this "visualization" is more confusing than the code.

[mjcg91]

build_array works like append in Python. Is will either create an array from a single value or append values to an existing array.

[mjcg91]

Btw if all you want to do is like the function above, you might as well do it in a for-each loop and directly plug the value to the output. It's gonna be much faster. If your array's construction is not based on a conditions, or if you don't have to access the active array data during the loop, there is no reason tobuse iterate or do-while loops. 

[g2m.agent]

the for-each loop gives me 2d array:

inside:

[mjcg91 · Accepted solution]

you don't need a build array node inside for each, nor have to init an empty array. Just plug the single values to the output. Also pay attention to port icons.

[g2m.agent]

thank you! that helps a lot.