Extracting HEC-RAS Results

Purpose: Lightweight skill index that navigates you to primary documentation sources. This skill does NOT duplicate content - it points you to where complete, authoritative information lives.

Primary Sources:

• HDF Class Reference: C:\GH\ras-commander\ras_commander\hdf\AGENTS.md (215 lines) - Complete class hierarchy, lazy loading patterns, decorators
• Library Context: C:\GH\ras-commander\ras_commander\CLAUDE.md - HDF architecture overview, subpackage organization
• Example Notebooks:
  • C:\GH\ras-commander\examples\10_1d_hdf_data_extraction.ipynb - 1D cross section results (unsteady)
  • C:\GH\ras-commander\examples\11_2d_hdf_data_extraction.ipynb - 2D mesh results (comprehensive)
  • C:\GH\ras-commander\examples\19_steady_flow_analysis.ipynb - Steady state results (complete workflow)
  • C:\GH\ras-commander\examples\18_breach_results_extraction.ipynb - Dam breach results
• Code Docstrings: All HDF classes have comprehensive docstrings with parameter details

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Quick Start

Minimal Working Example

from ras_commander import init_ras_project, HdfResultsPlan, HdfResultsMesh

# Initialize project
init_ras_project("C:/Projects/MyModel", "6.6")

# Check simulation type
is_steady = HdfResultsPlan.is_steady_plan("01")

# Extract results based on type
if is_steady:
    profiles = HdfResultsPlan.get_steady_profile_names("01")
    wse = HdfResultsPlan.get_steady_wse("01", profile_name="100 year")
else:
    max_wse = HdfResultsMesh.get_mesh_maximum("01", variable="Water Surface")

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Navigation Guide

1. Architecture & Organization

Read First: C:\GH\ras-commander\ras_commander\hdf\AGENTS.md

This is the definitive reference for:

• 18 HDF classes and their organization
• Module structure (Core, Geometry, Results, Infrastructure, Visualization)
• Class hierarchy and dependencies
• Lazy loading patterns for heavy dependencies
• Decorator usage (@staticmethod, @log_call, @standardize_input)
• File type expectations (plan_hdf vs geom_hdf)
• Common HDF paths in files

Key Sections:

• Lines 5-45: Module structure and organization
• Lines 47-114: Class hierarchy and dependencies
• Lines 116-138: Import patterns
• Lines 140-215: Adding new methods (decorator patterns, error handling)

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2. Complete Workflows

1D Unsteady Results: C:\GH\ras-commander\examples\10_1d_hdf_data_extraction.ipynb

Navigate to this notebook for:

• Cross section time series extraction (HdfResultsXsec)
• Output time handling
• Computation message extraction
• 1D hydraulic variables

2D Unsteady Results: C:\GH\ras-commander\examples\11_2d_hdf_data_extraction.ipynb

Navigate to this notebook for:

• 2D mesh maximum envelopes (HdfResultsMesh.get_mesh_maximum)
• Time series at specific locations
• Spatial grids and polygons
• Complete working examples with real data

Steady Flow Results: C:\GH\ras-commander\examples\19_steady_flow_analysis.ipynb

Navigate to this notebook for:

• Profile detection (get_steady_profile_names)
• Water surface elevation extraction by profile
• Multiple profile comparison
• Steady state metadata extraction
• Variable discovery (list_steady_variables)

Dam Breach Results: C:\GH\ras-commander\examples\18_breach_results_extraction.ipynb

Navigate to this notebook for:

• Structure identification (HdfStruc.list_sa2d_connections)
• Breach time series (HdfResultsBreach.get_breach_timeseries)
• Summary statistics and peak values
• Breach geometry evolution
• Complete breach workflow from detection to visualization

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3. Class Reference

Core HDF Classes (all in ras_commander/hdf/):

Class	Purpose	Primary Use
HdfResultsPlan	Plan-level results	Steady profiles, metadata, plan info, output times, computation messages
HdfResultsMesh	2D mesh results	Maximum envelopes, time series, spatial grids
HdfResultsXsec	Cross section results	1D time series, longitudinal profiles
HdfResultsBreach	Breach results	Dam breach time series, summary statistics, geometry evolution
HdfMesh	Mesh geometry	Cell polygons, face points, perimeter extraction
HdfXsec	XS geometry	Cross section coordinates, attributes
HdfStruc	Structure geometry	SA/2D connections, breach capability info
HdfHydraulicTables	HTAB extraction	Rating curves, property tables

Read: C:\GH\ras-commander\ras_commander\hdf\AGENTS.md lines 5-45 for complete class list and organization.

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4. Method Signatures

Instead of duplicating API documentation here, use these strategies:

Strategy 1: Read Docstrings Directly

from ras_commander import HdfResultsPlan
help(HdfResultsPlan.get_steady_wse)  # Complete parameter docs

Strategy 2: Check Source Files

Navigate to class files in C:\GH\ras-commander\ras_commander\hdf\:

• HdfResultsPlan.py - Lines 1-500 contain all steady/unsteady methods
• HdfResultsMesh.py - Lines 1-400 contain mesh extraction methods
• HdfResultsXsec.py - Lines 1-300 contain cross section methods
• HdfResultsBreach.py - Lines 1-400 contain breach methods

Strategy 3: Use Example Notebooks

Example notebooks show actual usage with real HEC-RAS projects:

• See notebook cells for working code patterns
• Notebook markdown explains each step
• Output cells show expected return structures

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Common Workflows (Quick Reference)

Detect Plan Type

is_steady = HdfResultsPlan.is_steady_plan("02")
plan_info = HdfResultsPlan.get_plan_info("02")

Return: Boolean for is_steady_plan(), DataFrame with program version, run type, etc. for get_plan_info()

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Steady Flow Extraction

# List profiles
profiles = HdfResultsPlan.get_steady_profile_names("02")

# Extract specific profile
wse = HdfResultsPlan.get_steady_wse("02", profile_name="100 year")

# Extract all profiles
wse_all = HdfResultsPlan.get_steady_wse("02")

# Discover variables
vars_dict = HdfResultsPlan.list_steady_variables("02")

Returns: List of profile names, DataFrame with River/Reach/Station/WSE columns

Full Details: C:\GH\ras-commander\examples\19_steady_flow_analysis.ipynb

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Unsteady Cross Section Time Series

# Get all variables as xarray Dataset
xsec_data = HdfResultsXsec.get_xsec_timeseries("01")

# Access specific variable
wse_ts = xsec_data["Water_Surface"]  # (time, cross_section)
velocity_ts = xsec_data["Velocity_Total"]

# Select specific cross section
target_xs = "River Reach 12345.6"
wse_at_xs = wse_ts.sel(cross_section=target_xs)

Returns: xarray Dataset with dimensions (time, cross_section), coordinates for River/Reach/Station

Full Details: C:\GH\ras-commander\examples\10_1d_hdf_data_extraction.ipynb

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2D Mesh Maximum Envelopes

# Get maximum water surface
max_wse = HdfResultsMesh.get_mesh_maximum("01", variable="Water Surface")

# Get maximum depth
max_depth = HdfResultsMesh.get_mesh_maximum("01", variable="Depth")

# Get maximum velocity
max_vel = HdfResultsMesh.get_mesh_maximum("01", variable="Velocity")

Returns: GeoDataFrame with columns: cell_id, max_value, max_time, geometry (Polygon)

Full Details: C:\GH\ras-commander\examples\11_2d_hdf_data_extraction.ipynb

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Dam Breach Results

from ras_commander import HdfStruc, HdfResultsBreach

# List structures
structures = HdfStruc.list_sa2d_connections("02")

# Get breach info
breach_info = HdfStruc.get_sa2d_breach_info("02")

# Extract time series
breach_ts = HdfResultsBreach.get_breach_timeseries("02", "Dam")

# Get summary statistics
summary = HdfResultsBreach.get_breach_summary("02", "Dam")

Returns: DataFrames with structure names, breach timing, flows, geometry evolution

Full Details: C:\GH\ras-commander\examples\18_breach_results_extraction.ipynb

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Integration Patterns

With hdf-analyst Skill

Division of Responsibility:

• This skill (extracting-hecras-results): Standard HEC-RAS result extraction using documented API
• hdf-analyst skill: Custom HDF path navigation, advanced xarray operations, performance optimization

Example Handoff:

# You handle standard extraction
max_wse = HdfResultsMesh.get_mesh_maximum("01", variable="Water Surface")

# Delegate to hdf-analyst for:
# - Custom HDF group navigation
# - Non-standard path queries
# - Advanced xarray transformations
# - Memory optimization for large files

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Common Issues & Solutions

Structure Name Mismatches

Issue: Structure names differ between plan files and HDF Solution: Always use HdfStruc.list_sa2d_connections() to get HDF names Example: Plan file "Dam" might be "BaldEagleCr Dam" in HDF

Missing Timesteps

Issue: Fewer timesteps than expected in results Solution: Check if simulation completed with HdfResultsPlan.get_compute_messages() Details: Partial runs will have truncated output

Large Memory Usage

Issue: Mesh time series extraction uses too much RAM Solution: Extract specific timesteps, not all Example: Use timestep_indices=[0, 50, 100] instead of timestep_indices="all"

Variable Not Found

Issue: Cannot find expected variable in HDF Solution: Use HdfResultsPlan.list_steady_variables() or inspect HDF structure directly Note: Variable names differ between HEC-RAS versions

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Related Skills

• executing-hecras-plans: Run simulations to generate HDF results (prerequisite)
• hdf-analyst: Advanced HDF operations and custom analysis (advanced use cases)

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Navigation Checklist

When a user asks about HEC-RAS result extraction:

1. Start Here: Determine if they need steady or unsteady extraction
2. Navigate to Example: Point to relevant notebook (10, 11, 18, or 19)
3. Check Class Reference: If they need architectural details, point to hdf/AGENTS.md
4. Read Docstrings: For parameter details, use help() or read source files
5. Avoid Duplication: Never replicate content that exists in primary sources

Primary Sources Are Always More Current: This skill is a navigation aid. When in doubt, trust the example notebooks and code docstrings over this file.

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Summary

Total Lines: ~350 (lightweight index) Purpose: Navigate to primary sources, not duplicate them When to Use: User needs HEC-RAS result extraction guidance Primary Sources:

• Architecture: ras_commander/hdf/AGENTS.md
• Workflows: examples/400_1d_hdf_data_extraction.ipynb, examples/410_2d_hdf_data_extraction.ipynb, examples/401_steady_flow_analysis.ipynb, examples/420_breach_results_extraction.ipynb
• API Details: Code docstrings in ras_commander/hdf/*.py

Key Principle: Point to authoritative sources, don't replicate them.