Extracting HEC-RAS Results

When the user asks to extract HEC-RAS results, use the patterns below. Read the primary sources for complete details -- do not duplicate their content here.

Primary Sources:

• HDF Class Reference: ras_commander/hdf/AGENTS.md - Canonical HDF package contract, module families, lazy loading rules, decorators
• Library Context: ras_commander/AGENTS.md - HDF architecture overview, subpackage organization
• Example Notebooks:
  • examples/400_1d_hdf_data_extraction.ipynb - 1D cross section results (unsteady)
  • examples/410_2d_hdf_data_extraction.ipynb - 2D mesh results (comprehensive)
  • examples/401_steady_flow_analysis.ipynb - Steady state results (complete workflow)
  • examples/420_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("path/to/project", "7.0")

# 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: ras_commander/hdf/AGENTS.md

Read this first 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:

• Module families and common entry points
• Implementation rules for decorators, lazy loading, and HDF input handling
• Input and output rules for flexible plan/path/HDF handles

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2. Complete Workflows

1D Unsteady Results: examples/400_1d_hdf_data_extraction.ipynb

Read this notebook when you need:

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

2D Unsteady Results: examples/410_2d_hdf_data_extraction.ipynb

Read this notebook when you need:

• 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: examples/401_steady_flow_analysis.ipynb

Read this notebook when you need:

• 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: examples/420_breach_results_extraction.ipynb

Read this notebook when you need:

• 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: ras_commander/hdf/AGENTS.md for the class families and package 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 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: examples/401_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: examples/400_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: examples/410_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: examples/420_breach_results_extraction.ipynb

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Integration Patterns

With hdf-analyst Skill

Use this skill for standard API-based extraction. Delegate to hdf-analyst agent for custom HDF path navigation, advanced xarray operations, or 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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Cross-References

Rules (auto-loaded context):

• .claude/rules/hec-ras/hdf-files.md -- Read for HDF domain overview and steady/unsteady detection
• .claude/rules/python/api-first-principle.md -- Follow the API-first mandate for all extraction

Agents (delegate when needed):

• hdf-analyst -- Delegate for advanced HDF analysis beyond standard API
• hecras-results-analyst -- Delegate for results interpretation and quality assessment

Skills (related workflows):

• hecras_compute_plans -- Upstream: run simulations that produce HDF results
• hecras_parse_compute-messages -- Use to verify execution completed before extracting

Primary sources:

• ras_commander/hdf/AGENTS.md -- Complete class hierarchy and architecture
• examples/400_1d_hdf_data_extraction.ipynb -- 1D unsteady extraction workflow
• examples/410_2d_hdf_data_extraction.ipynb -- 2D mesh results workflow
• examples/401_steady_flow_analysis.ipynb -- Steady state extraction workflow
• examples/420_breach_results_extraction.ipynb -- Dam breach results workflow