Feature - Grow!

[raghavakumar8]

Adds the ability to grow a gridmap instance efficiently (using Eigen functions) in different directions.

Resolves #132.

[artivis]

Plain curiosity,
why are you using conservativeResizeLike rather than conservativeResize ??
The function conservativeResize allocates a temporary matrix under the hood, so I would imagine that conservativeResizeLike does the same. Thus isn't the temporary matrix like a waste of memory ?

[raghavakumar8]

conservativeResize doesn't let you initialize the values of new elements, conservativeResizeLike does. This is important when you want to be able to guarantee that every new grid cell is initalized to 0.0, for instance.

In principle I could use conservativeResize, loop through all new cells and manually initialize them, but I suspect that would be less efficient.

[artivis]

Ok I see your point.
Still I think a plain conservativeResize followed by manually setting the uninitialized values would be better as you don't really need allocating matrix like, especially as the matrix grows large.
Rather than looping over uninitialized values you can use the block functions, something along the lines :

data.second.conservativeResize(size(0), size(1));
// Assuming that resizing to larger dimension appends 
// rows at the bottom and cols at the right side.
// Set value for appended bottom rows
data.second.block(size_(0), 0, row_delta, size(1)).setConstant(value); 
// Set value for appended top-left block (remaining unintialized)
data.second.topRightCorner(size(0), col_delta).setConstant(value);

I haven't checked that the indices are actually correct ^^, but that's the general idea.

Edit: you could also use the block scheme to swap the whole original matrix over the new layout.

[brunoeducsantos]

Is this feature working? What is it stopping from going to production?

[raghavakumar8]

Just waiting for an approving review. We have been using this feature extensively in production at our company.

[rupertbayern]

this is very nice feature and exactly what I needed! A merge would be good.

[stevencolinmartin]

+1 for useful feature and would be good to have merged

[maximilianwulf]

Yes, will import it.

[maximilianwulf]

@raghavakumar8 could you merge master back into your branch?

[maximilianwulf]

Closing in favor of #330 which has more up-to-date master.