Data Export and Comparison

Data Export and Comparison

Relevant source files

The following files were used as context for generating this wiki page:

• AGENTS.md
• scripts/check_ui_size_limits.py
• src/core/comparison_manager.py
• src/core/export/csv_exporter.py
• src/gui/widgets/plot_comparer.py
• tests/core/export/init.py
• tests/core/export/test_csv_exporter.py
• tests/logic_verification/core/test_comparison_manager.py
• tests/logic_verification/gui/test_plot_comparer.py

MeasureLab provides a centralized infrastructure for capturing, comparing, and exporting measurement data. This system allows users to aggregate results from disparate modules—such as the Spectrum Analyzer and Network Analyzer—into a single visual environment for overlay analysis and high-fidelity export to external formats.

The architecture relies on a shared registry for data traces and a dedicated module for visual comparison.

Data Flow Overview

The following diagram illustrates how measurement data originates in analysis modules and flows through the ComparisonManager to either the PlotComparer for visualization or the ExportManager for file generation.

Measurement Data Pipeline

graph LR
    subgraph "Analysis Modules"
        SA["SpectrumAnalyzerWidget"]
        NA["NetworkAnalyzerWidget"]
        LA["LinearityAnalyzerWidget"]
    end

    subgraph "Core Registry"
        CM["ComparisonManager (Singleton)"]
        CT["ComparisonTrace (Data Object)"]
    end

    subgraph "Consumers"
        PCW["PlotComparerWidget (UI)"]
        EM["ExportManager (Logic)"]
    end

    SA -- "get_comparable_data()" --> CT
    NA -- "get_comparable_data()" --> CT
    LA -- "get_comparable_data()" --> CT
    
    CT -- "add_trace()" --> CM
    CM -- "trace_added signal" --> PCW
    PCW -- "export_traces()" --> EM

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Sources: src/core/comparison_manager.py:154-185, src/gui/widgets/plot_comparer.py:62-90, tests/logic_verification/gui/test_plot_comparer.py:144-170

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Comparison Infrastructure

The comparison system is built around a "Snapshot" philosophy. Instead of live-streaming data between widgets, modules package their current state into a standardized ComparisonTrace object.

ComparisonManager

The ComparisonManager is a singleton registry src/core/comparison_manager.py:154-170 that acts as the central hub for all traces. It manages the lifecycle of measurement data, providing methods to add, remove, and retrieve traces src/core/comparison_manager.py:181-190. It also handles native .mlcomp file serialization for saving and loading measurement sessions src/core/comparison_manager.py:126-151.

ComparisonTrace

The ComparisonTrace class is the primary data structure for cross-module exchange. It encapsulates:

• Metadata: Source module name, timestamp, and plot type (e.g., frequency_response, spectrum) src/core/comparison_manager.py:55-60.
• Axis Information: AxisMetadata defining units (V, Hz, dB), dimensions, and whether the axis is logarithmic src/core/comparison_manager.py:35-51.
• Data Arrays: NumPy-backed arrays for X, Y1, and optional Y2 (secondary axis) data src/core/comparison_manager.py:68-71.
• Calibration: CalibrationInfo containing sensitivity and offsets applied at the time of measurement src/core/comparison_manager.py:12-31.

For details on the comparison registry and interface, see Plot Comparer and Comparison Manager.

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Plot Comparer

The Plot Comparer is a specialized MeasurementModule src/gui/widgets/plot_comparer.py:38-52 designed for visual overlay and delta analysis.

Feature	Implementation
Multi-Domain Support	Filters traces by domain (Frequency vs. Time) using filter_combo src/gui/widgets/plot_comparer.py:135-142.
Trace Management	Uses a QTreeWidget to manage visibility, colors, and Y-axis assignments src/gui/widgets/plot_comparer.py:19-21.
Interactive Readout	Provides crosshair cursors and a readout_label for precise value inspection src/gui/widgets/plot_comparer.py:127-141.
Normalization	Supports per-trace gain offsets and time shifts via inline spin boxes src/gui/widgets/plot_comparer.py:88-95.
Dual Y-Axes	Synchronizes a secondary ViewBox for comparing mixed units (e.g., Magnitude vs. Phase) src/gui/widgets/plot_comparer.py:174-184.

For details on the comparison UI, see Plot Comparer and Comparison Manager.

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Export System

The export subsystem handles the transformation of ComparisonTrace data into industry-standard formats. It uses a plugin-based architecture where different formats are handled by specific exporter classes.

Export Architecture

• ExportManager: Orchestrates the export process and manages available plugins.
• BaseTraceExporter: The abstract base class defining the interface for all exporters src/core/export/csv_exporter.py:12.
• CsvTraceExporter: Implements CSV and TXT export with support for "merged" (common X-axis) or "independent" (multi-column) layouts src/core/export/csv_exporter.py:37-59.
• Sanitization: Includes security measures like _sanitize_csv_field to prevent CSV formula injection attacks src/core/export/csv_exporter.py:29-35.

Data Export Mapping

classDiagram
    class ComparisonTrace {
        +String id
        +String name
        +AxisMetadata x_axis
        +AxisMetadata y_axis
        +NDArray x_data
        +NDArray y_data
    }

    class BaseTraceExporter {
        <<interface>>
        +export_traces(filepath, traces, options)
    }

    class CsvTraceExporter {
        +_export_merged()
        +_export_independent()
        +_sanitize_csv_field()
    }

    class JsonExporter {
        +export_traces()
    }

    BaseTraceExporter <|-- CsvTraceExporter
    BaseTraceExporter <|-- JsonExporter
    CsvTraceExporter ..> ComparisonTrace : Serializes

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Sources: src/core/export/csv_exporter.py:12-60, src/core/comparison_manager.py:55-77

For details on the export plugins and sanitization, see Export System.

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Child Pages

• Export System — Detailed look at the ExportManager, CsvTraceExporter, and security protocols.
• Plot Comparer and Comparison Manager — Technical breakdown of the singleton registry and the interactive comparison widget.

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