Implement getNodeFromId method

[carolc24]

I think the following method has the wrong docs associated with it:

_GraphfabExport gf_reaction* gf_nw_getRxnp(gf_network *n, size_t i)

Get the node at index i.

Ps what I need is a method like:

index gf_getNodeIndex (char *nodeId);

Unfortunately I don't have a way to get a node from the ID without looping through the nodes, which is probably the simplest way to implement this. Something like:

gf_node gf_nw_getNodeFromId(gf_network *nw, const char id) {
int k;
// add checks here for nw != NULL etc

for(k = 0; k< gf_nw_getNumNodes(nw); ++k) {
if( !strcmp(gf_node_getID(gf_nw_getNodep(nw)) , id) ) {
return gf_nw_getNodep(nw);
}
}

// not found: set some error condition here
}

You need to pass the network to this method or else it doesn't know which network you are referring to (you can have multiple networks loaded in theory - it's never been tested). Since you're passing the network, it's a method on a network object, hence the "gf_nw" prefix. That prefix convention is used throughout the C API. Hope this helps.