Results Export

Overview

Results are exported from HEC-RAS plan HDF files (*.p??.hdf). ras-commander's HdfResultsMesh.get_mesh_summary_output() returns one row per 2D mesh cell with summary statistics for the requested variable.

Available Variables

Common 2D mesh summary variables (exact names depend on what was computed in the HEC-RAS plan):

HEC-RAS Variable	Output Column	Description
Maximum Depth	maximum_depth	Maximum water depth over simulation period
Maximum Water Surface	maximum_water_surface	Maximum water surface elevation
Maximum Velocity	maximum_velocity	Maximum flow velocity
Maximum Face Velocity	maximum_face_velocity	Maximum velocity at cell faces
Minimum Depth	minimum_depth	Minimum water depth

Column names are snake_case — ras-commander normalizes all variable names.

Use list_available_summary_variables() to discover what a specific plan HDF contains:

from ras2cng.results import list_available_summary_variables
variables = list_available_summary_variables(Path("model.p01.hdf"))
print(variables)  # ['Maximum Depth', 'Maximum Water Surface', ...]

Polygon Join

Results from HdfResultsMesh are points (one per mesh cell centroid). To get polygon geometry suitable for choropleth maps and area calculations, provide a --geometry GeoParquet file:

ras2cng results model.p01.hdf max_depth.parquet \
  --geometry mesh_cells.parquet \
  --var "Maximum Depth"

The merge is performed on (mesh_name, cell_id) — both columns must be present in the geometry file. Result: each row is a mesh cell polygon with the hydraulic result attribute attached.

Export All Variables

# Export all available variables to a directory
ras2cng results model.p01.hdf ./results/ --all --geometry mesh_cells.parquet

Each variable is written to a separate file: results/maximum_depth.parquet, etc.

Python API

from ras2cng.results import (
    export_results_layer,
    export_all_variables,
    merge_all_variables,
    list_available_summary_variables,
)
from pathlib import Path

# List variables
variables = list_available_summary_variables(Path("model.p01.hdf"))

# Export single variable (points, no geometry join)
export_results_layer(
    plan_hdf=Path("model.p01.hdf"),
    output=Path("max_depth_points.parquet"),
    variable="Maximum Depth",
)

# Export with polygon join
export_results_layer(
    plan_hdf=Path("model.p01.hdf"),
    output=Path("max_depth_polygons.parquet"),
    variable="Maximum Depth",
    geom_file=Path("mesh_cells.parquet"),
)

# Export all variables to separate parquet files
exported = export_all_variables(
    plan_hdf=Path("model.p01.hdf"),
    output_dir=Path("./results/"),
    geom_file=Path("mesh_cells.parquet"),
)
print(f"Exported {len(exported)} variables: {exported}")

# Merge all variables into one GeoDataFrame with `layer` column
# (used by archive_project() for consolidated output)
gdf = merge_all_variables(
    plan_hdf=Path("model.p01.hdf"),
    mesh_cells_gdf=mesh_cells_gdf,  # GeoDataFrame with polygon geometry
)
# gdf has `layer` column: 'maximum_depth', 'maximum_water_surface', ...