Selecting network subsets

[jpalm3r]

Selective loading for Network.from_res1d()

Large Res1D files can contain hundreds of nodes and thousands of intermediate
gridpoints. Loading all of that data into memory is slow and can cause memory
issues when you only care about the handful of nodes where observations exist.

Network.from_res1d() now accepts two optional arguments — nodes and
reaches — to control what gets loaded:

Argument	"all" (default)	[]	specific name(s)
nodes	load all node timeseries	skip all node data	load only the listed nodes
reaches	populate all gridpoints	skip all gridpoints	populate only the listed reaches

The full network topology is always constructed regardless of these
settings, so find(), recall(), and graph algorithms continue to work
across the entire network.

Usage

# Default — load everything (backwards compatible)
network = Network.from_res1d("model.res1d")

# Load only the nodes with observations, skip all gridpoints
network = Network.from_res1d(
    "model.res1d",
    nodes=["node_a", "node_b"],
    reaches=[],
)

# Load selected nodes + gridpoints for one reach only
network = Network.from_res1d(
    "model.res1d",
    nodes=["node_a", "node_b"],
    reaches=["reach_1"],
)

Notes

- Both parameters accept "all", a single string, or a list of strings,
making the API fully symmetric.
- A UserWarning is raised if the file contains a node or reach literally
named "all", since that conflicts with the sentinel value. The workaround
is to wrap it in a list: nodes=["all"].

Streamlining matching

NodeObservation now accepts three forms for node=, with lazy resolution handled by NetworkModelResult at match time.

node= options

Form	Example	Description
int	node=42	Direct integer ID — unchanged behaviour
str	node="78"	Original node alias from the source format (e.g. Res1D node name)
tuple	node=("94l1", 21.285)	Breakpoint identified by (edge_id, distance)

String and tuple forms are resolved inside NetworkModelResult.extract() via an alias map derived from the Network object. A clear ValueError is raised if an alias cannot be resolved.