Adding origin shift to GridCells for translations

[jquinnlee]

Proposing a new param for the GridCell class - "shift_origin"
Enables user to provide x-y coordinates for origin of GridCells, with default at (0., 0.)

Sorry for taking ages to get this in!

[TomGeorge1234]

Hey Quinn, I'm not sure I even remember where we spoke about this!

This functionality would be nice but the way you are proposing to do it just overwrites the phase offsets. It is also not implemented right, I think you would need the parameter to be a list or array, not a tuple.

Either way, I think the current API does strictly (if not super intuitively) expose this functionality by allowing uses to set the phase offsets as shown on line 1183. Adding a new parameter would be redundant and might risk confusing things.

RatInABox/ratinabox/Neurons.py

Line 1183 in 92f0d99

origin = self.gridscales.reshape(-1, 1) * self.phase_offsets / (2 * np.pi)

Proposed solution exploiting current API

Wouldn't it be best for you to

1. Choose your grid scales gridscales = np.array([]) #(n,)
2. Choose your desired origins origins = np.array([]) # (n,2)
3. Compute your phase offsets by inverting the equation in line 1183 phase_offsets = 2*np.pi*origins / grid scales[:,None] #(n,2)
4. Initialise:

GCs = GridCells(Agent, params={
                        'gridscale':gridscales,
                        'phase_offset':phase_offsets})

If you don't know your grid scales (e.g. because they're being sampled at initialisation) you could initialise the grid cells, then get the scales, then set GCs.phase_offsets afterwards. If you wanted you could even have a different origin for each grid (as shown below).

Working example

You can see it works because each GC is centred on its new origin (green dot).

# Standard initialisation
Env = Environment()
Ag = Agent(Env)
GCs = GridCells(Ag)

# Set the desired origins
origins = np.random.uniform(0,1,(GCs.n,2)) # Put your desired origins here

# Overwrite phase offsets to place the grid cells at the desired origins
GCs.phase_offsets = 2 * np.pi * origins / GCs.gridscales[:,None]

# Visualise and check that the phase offsets are correct
fig, axs = GCs.plot_rate_map()
for i in range(GCs.n):
    axs[i].scatter(*origins[i], c='g', s=100)

[jquinnlee]

Hey Tom,

Sorry for my oversight on this redundancy! I confirmed in my workflow that your suggested solution with overwriting phase_offsets works perfectly.

Thanks!