Model Playground - Veydra Documentation

Overview

The Model Playground is Veydra’s central workspace where you build, modify, and test your system dynamics models. It provides an interactive environment with real-time feedback and powerful visualization tools.

Playground Modes

The Model Playground is organized around a mode-based workflow that guides you through the full modeling lifecycle. Each mode focuses on a specific phase and adapts the UI — showing relevant panels, controls, and AI assistant context. Switch modes using the color-coded buttons in the top navigation bar.

Presentation

Interactive guided walkthrough of the model with slides, quizzes, and embedded content

Design

Build and structure your model — edit parameters, code, and stock-flow diagrams

Calibrate

Fine-tune parameters to match real-world data (Pro)

Experiment

Run what-if scenarios and explore different futures

Decide

Compare multiple scenarios side-by-side for decision analysis (Pro)

Presentation Mode

A read-only guided experience for learning about a model. Content is displayed as scrollable slides with a sticky table of contents sidebar. Slides can include rich text, embedded videos, quizzes, and buttons that navigate to other modes.

No editable controls — Model Controls, System Map, and Code Editor are hidden
AI Assistant adapts with presentation-specific prompts like “Take a Quick Quiz” and “Summarize this model”
Ideal for onboarding, classroom use, or sharing insights with stakeholders

Design Mode

The primary building mode where all structural changes happen. Parameter changes in Design mode update the baseline configuration that applies across all scenarios.

Model Editor Panel — Full access to all sliders (stocks, flows, parameters, simulation settings)
Stock-Flow Diagram — Fully expanded with Flow, Causal, Params, and Loops tabs
Code Editor — Direct Python code editing with Pyodide execution panel
Charts are hidden so you can focus on model structure

Changes made in Design mode affect the baseline for ALL scenarios. Use Experiment mode for what-if analysis.

Calibrate Mode (Pro)

Fine-tune your model to match historical or real-world data. Calibration changes update both baseline and scenario values simultaneously.

Calibration Panel — Specialized parameter controls for data fitting
Charts visible — See how parameter adjustments affect model output in real time
System Map — Minimized by default but expandable
Supports parameter estimation, historical fit, and validation workflows

Calibrate mode requires a Pro subscription. Free users are redirected to Experiment mode.

Experiment Mode

Run what-if scenarios using your calibrated baseline. Slider changes only affect the current scenario’s post-intervention behavior — the baseline stays fixed for comparison.

Model Controls — Shows parameter sliders (not simulation settings) with save/load scenario support
Compare Mode — Enabled by default, showing baseline vs. scenario on charts
Scenario Selector — Save, load, rename, and delete named scenarios
Specialized visualizations — Gantt charts, wait-time scatter plots, spatial visualizations (for applicable models)

Decide Mode (Pro)

Compare multiple saved scenarios side-by-side to make strategic decisions. Automatically selects the baseline plus up to two user scenarios for comparison.

Multi-Scenario Selector — Choose which scenarios to overlay on charts
Multi-Stock Chart Area — All stocks shown with scenario overlays
Analysis Card — Aggregated comparison metrics across scenarios
System Map is fully hidden to maximize chart space

Mode Availability

Not all modes appear for every model. The available modes are determined by the model’s metadata:

Mode	Default	Notes
Design	Always available	Core building mode
Calibrate	Always available	Pro-gated
Experiment	Always available	Primary analysis mode
Presentation	Opt-in per model	Requires slide content
Decide	Opt-in per model	Pro-gated

AI Assistant Per Mode

The AI Assistant panel automatically adapts to the current mode with a matching color theme, contextual welcome message, and mode-specific action buttons. For example, Design mode offers “Start a guided tutorial” while Decide mode offers “Strategy Comparison” and “Risk Analysis”.

Key Components

The Model Playground consists of several integrated panels that work together:

Model Controls

Parameter adjustment and simulation controls

Stock-Flow Diagram

Visual representation of your model structure

Chart Area

Real-time simulation results and comparisons

Code Editor

Direct Python code editing and customization

Model Controls Panel

Parameter Management

The Model Controls panel is your command center for model interaction:

Active Parameters: Parameters available for real-time adjustment
Parameter Sliders: Interactive controls for each parameter
Reset Functions: Quickly return to default values
Scenario Management: Save and load different parameter sets

Control Features

Parameter Activation

Mark parameters as “Active” to enable real-time slider controls during simulation

Reset All Parameters

Use the refresh button to reset all parameters to defaults while keeping them active for quick experimentation

Scenario Comparison

Enable “Compare Mode” to see baseline vs current scenario side-by-side

Stock-Flow Diagram Area

Visual Model Building

The diagram area provides an interactive view of your model’s structure:

Stock Elements: Rectangular boxes representing accumulations
Flow Elements: Arrows showing rates of change
Connectors: Links showing influence relationships
Parameters: Variable elements that can be adjusted

Interactive Features

Drag and Drop: Reposition elements for better layout
Real-time Updates: See value changes during simulation
Zoom and Pan: Navigate large, complex models
Element Properties: Click to edit element details

The diagram automatically updates to reflect changes made in the code editor

Chart Area

Visualization Options

Single Stock View

Focus on individual model components

Multi-Stock View

Display all stocks simultaneously

Comparison Mode

Baseline vs scenario analysis

Data Export

Export simulation results

Chart Features

Interactive Legends: Show/hide data series
Zoom and Pan: Explore different time ranges
Tooltips: Detailed value information on hover
Time Units: Automatic scaling (days, weeks, months, years)

Code Editor

Python-Based Models

Veydra uses Python for model execution, giving you full flexibility:

# Example model structure
def model_function(parameters):
    # Define stocks and flows
    population = parameters['initial_population']
    growth_rate = parameters['growth_rate']
    
    # Calculate changes
    new_population = population * (1 + growth_rate)
    
    return {
        'population': new_population,
        'growth': new_population - population
    }

Editor Features

Syntax Highlighting: Python code formatting
Auto-completion: Intelligent code suggestions
Error Detection: Real-time syntax checking
Version Control: Git integration for change tracking

Simulation Engine

Real-Time Execution

The simulation engine processes your models using:

Pyodide Integration: Python execution in the browser
WebAssembly: High-performance computation
Incremental Updates: Fast parameter changes
Memory Management: Efficient data handling

Performance Features

Caching: Smart caching of model files and configurations
Parallel Processing: Multiple scenario execution
Optimization: Automatic performance tuning
Error Handling: Graceful failure recovery

Workflow Example

Model Setup

Load or create a new model
Review the stock-flow diagram
Identify key parameters to activate

Parameter Configuration

Mark important parameters as “Active”
Set initial values using sliders
Configure simulation time range

Simulation

Run initial baseline simulation
Adjust parameters in real-time
Compare different scenarios

Analysis

Review chart results
Export data for further analysis
Save interesting scenarios

Advanced Features

Git Integration

Version Control: Track all model changes
Branching: Experiment with different approaches
Merging: Collaborate on model development
History: Review past versions and changes

Collaboration Tools

Real-time Sharing: Multiple users in same playground
Comments: Annotate models and results
Permissions: Control who can edit vs view
Change Notifications: Track team member activities

Use the Model Playground’s reset functionality to quickly experiment with different parameter combinations while maintaining your baseline for comparison

Getting Started

Platform Features

Simulation Components

Tools

Integrations

Development

​Overview

​Playground Modes

Presentation

Design

Calibrate

Experiment

Decide

​Presentation Mode

​Design Mode

​Calibrate Mode (Pro)

​Experiment Mode

​Decide Mode (Pro)

​Mode Availability

​AI Assistant Per Mode

​Key Components

Model Controls

Stock-Flow Diagram

Chart Area

Code Editor

​Model Controls Panel

​Parameter Management

​Control Features

​Stock-Flow Diagram Area

​Visual Model Building

​Interactive Features

​Chart Area

​Visualization Options

Single Stock View

Multi-Stock View

Comparison Mode

Data Export

​Chart Features

​Code Editor

​Python-Based Models

​Editor Features

​Simulation Engine

​Real-Time Execution

​Performance Features

​Workflow Example

​Advanced Features

​Git Integration

​Collaboration Tools

​Next Steps

Simulation Features

Model Controls Guide

Overview

Playground Modes

Presentation Mode

Design Mode

Calibrate Mode (Pro)

Experiment Mode

Decide Mode (Pro)

Mode Availability

AI Assistant Per Mode

Key Components

Model Controls Panel

Parameter Management

Control Features

Stock-Flow Diagram Area

Visual Model Building

Interactive Features

Chart Area

Visualization Options

Chart Features

Code Editor

Python-Based Models

Editor Features

Simulation Engine

Real-Time Execution

Performance Features

Workflow Example

Advanced Features

Git Integration

Collaboration Tools

Next Steps