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Module: statistics.js

Comprehensive Analysis of statistics.js

Module Name

  • Module Name: statistics.js

Primary Objectives

  • Purpose: This module is designed to calculate and analyze various statistics related to shorelines and transects. It includes functions to compute distances, classify changes, and generate comprehensive statistical summaries.

Critical Functions

  1. calculateDistances:

    • Role: Calculates the distance of each shoreline to a point of interest on a transect.
    • Parameters: transect, baseline, shorelines
    • Returns: ee.Dictionary containing distances.

  2. estevesLabelling:

    • Role: Classifies the transect change rate using intervals proposed by Esteves and Finkl (1998).
    • Parameters: lrr (linear regression rate)
    • Returns: ee.String with the classified label.

  3. calculateStatistics:

    • Role: Computes general DSAS statistics (SCE, NSM, EPR, LRR) and Esteves classification for a transect.
    • Parameters: measurement (dictionary of distances)
    • Returns: ee.Dictionary with the calculated statistics.

  4. complementaryProperties:

    • Role: Appends useful transect data to its properties.
    • Parameters: transect, measurement, keepProps
    • Returns: ee.Dictionary with useful and kept properties.

  5. generateTransectsStatistics:

    • Role: Adds DSAS statistics and Esteves classification to transects.
    • Parameters: transects, baseline, shorelines, keepProps
    • Returns: ee.List<ee.Feature> with added statistics.

  6. summaryShorelineStatistics:

    • Role: Adds statistics about the distances observed in transects to shorelines.
    • Parameters: transects, shorelines
    • Returns: ee.FeatureCollection with added statistics.

Key Variables

  • distanceKey: Key for distance in the dictionary.
  • idKey: Key for ID in the dictionary.
  • poi: Point of interest on the transect.
  • distanceTo: Function to calculate distance to a coordinate.
  • classification: Result of Esteves classification.
  • distanceList: List of distances from the measurement dictionary.
  • initialState: Initial state for reducing distances.
  • stats: Reduced statistics dictionary.
  • regression: List of regression points.
  • trend: Result of linear regression and correlation.
  • summary: Summary dictionary for complementary properties.
  • shorelineList: List of shorelines.
  • shorelineTable: Dictionary mapping shoreline IDs to features.
  • distances: Flattened list of distances.
  • transformed: Dictionary of reduced distances per shoreline.

Interdependencies

  • Interactions with Other Components:
    • earth-engine: Utilizes Earth Engine services for geospatial computations.
    • utils: Uses utility functions like combineReducers and serializeList.
    • metadata: Accesses common metadata constants like TIME_START, INTERNALS, and ESTEVES_LABELS.
    • common/utils: Uses common utility constants like EPOCH.

Core vs. Auxiliary Operations

  • Core Operations:

    • Distance calculations (calculateDistances)
    • Statistical computations (calculateStatistics)
    • Classification (estevesLabelling)
    • Generating transect statistics (generateTransectsStatistics)
    • Summarizing shoreline statistics (summaryShorelineStatistics)

  • Auxiliary Operations:

    • Appending complementary properties (complementaryProperties)

Operational Sequence

  1. Distance Calculation: calculateDistances computes distances from shorelines to transects.
  2. Classification: estevesLabelling classifies the linear regression rate.
  3. Statistical Computation: calculateStatistics computes various statistics for the transects.
  4. Property Appending: complementaryProperties appends additional properties to transects.
  5. Transect Statistics Generation: generateTransectsStatistics integrates all computations and classifications into transects.
  6. Shoreline Statistics Summary: summaryShorelineStatistics summarizes the statistics for shorelines.

Performance Aspects

  • Performance Considerations:
    • Efficient use of Earth Engine's parallel processing capabilities.
    • Iterative reduction operations for large datasets.
    • Conditional checks to handle edge cases and empty collections.

Reusability

  • Adaptability for Reuse:
    • Functions are modular and can be reused in different contexts involving geospatial analysis.
    • Parameterized functions allow for flexibility in input data.
    • Utility functions like combineReducers and serializeList enhance reusability.

Usage

  • How It Is Used:
    • Integrated into a larger geospatial analysis system.
    • Called by other modules or scripts to compute and append statistical data to geospatial features.
    • Utilized in workflows involving shoreline and transect analysis.

Assumptions

  • Assumptions Made:
    • Input data (transects, shorelines, baseline) are correctly formatted and valid.
    • Earth Engine services are available and functioning.
    • Metadata constants (TIME_START, INTERNALS, ESTEVES_LABELS) are correctly defined.
    • Utility functions (combineReducers, serializeList) are available and correctly implemented.

This comprehensive analysis provides a detailed understanding of the statistics.js module, its functions, and its role within a larger geospatial analysis system.

Flow Diagram [via mermaid]

graph TD
    A[calculateDistances] --> B[calculateStatistics]
    B --> C[estevesLabelling]
    B --> D[complementaryProperties]
    D --> E[generateTransectsStatistics]
    E --> F[summaryShorelineStatistics]

Module: statistics.js

Comprehensive Analysis of statistics.js

Module Name

  • Module Name: statistics.js

Primary Objectives

  • Purpose: This module is designed to calculate and analyze various statistics related to shorelines and transects. It includes functions to compute distances, classify changes, and generate comprehensive statistical summaries.

Critical Functions

  1. calculateDistances:

    • Role: Computes the distance of each shoreline to a point of interest on a transect.
    • Parameters: transect, baseline, shorelines
    • Returns: ee.Dictionary containing distances.

  2. estevesLabelling:

    • Role: Classifies the transect change rate using intervals proposed by Esteves and Finkl (1998).
    • Parameters: lrr (linear regression rate)
    • Returns: ee.String representing the classification.

  3. calculateStatistics:

    • Role: Calculates general DSAS statistics (SCE, NSM, EPR, LRR) and Esteves classification for a transect.
    • Parameters: measurement (dictionary of distances)
    • Returns: ee.Dictionary containing the statistics.

  4. complementaryProperties:

    • Role: Appends useful transect data to its properties.
    • Parameters: transect, measurement, keepProps
    • Returns: ee.Dictionary with useful and kept properties.

  5. generateTransectsStatistics:

    • Role: Adds DSAS statistics and Esteves classification to transects.
    • Parameters: transects, baseline, shorelines, keepProps
    • Returns: ee.List<ee.Feature> with added statistics.

  6. summaryShorelineStatistics:

    • Role: Adds statistics about the distances observed in transects to shorelines.
    • Parameters: transects, shorelines
    • Returns: ee.FeatureCollection with added statistics.

Key Variables

  • distanceKey: Key for distance in the dictionary.
  • idKey: Key for ID in the dictionary.
  • poi: Point of interest on the transect.
  • distanceTo: Function to calculate distance to a coordinate.
  • classification: Result of Esteves classification.
  • distanceList: List of distances from the measurement dictionary.
  • initialState: Initial state for reducing distances.
  • stats: Reduced statistics dictionary.
  • regression: List of regression points.
  • trend: Result of linear regression and correlation.
  • summary: Summary dictionary for complementary properties.

Interdependencies

  • Interactions with Other Components:
    • Earth Engine (ee): Utilizes Google Earth Engine for geospatial computations.
    • Common Metadata: Imports constants like TIME_START, INTERNALS, ESTEVES_LABELS.
    • Utilities: Uses utility functions like combineReducers, serializeList.

Core vs. Auxiliary Operations

  • Core Operations:

    • Distance calculation (calculateDistances)
    • Statistical analysis (calculateStatistics)
    • Classification (estevesLabelling)
    • Generating transect statistics (generateTransectsStatistics)
    • Summarizing shoreline statistics (summaryShorelineStatistics)

  • Auxiliary Operations:

    • Appending properties (complementaryProperties)
    • Utility functions for combining reducers and serializing lists.

Operational Sequence

  1. Distance Calculation: calculateDistances computes distances from shorelines to transects.
  2. Statistical Analysis: calculateStatistics processes these distances to generate DSAS statistics.
  3. Classification: estevesLabelling classifies the transect change rate.
  4. Property Appending: complementaryProperties adds useful properties to transects.
  5. Transect Statistics Generation: generateTransectsStatistics integrates all previous steps to enrich transects with statistics.
  6. Shoreline Statistics Summary: summaryShorelineStatistics aggregates and summarizes statistics for shorelines.

Performance Aspects

  • Considerations:
    • Efficiency: Uses Earth Engine's efficient geospatial computation capabilities.
    • Scalability: Designed to handle large datasets typical in geospatial analysis.
    • Optimization: Utilizes reducers and efficient data structures to minimize computation time.

Reusability

  • Adaptability:
    • Functions are modular and can be reused in different contexts involving geospatial analysis.
    • Utility functions like combineReducers and serializeList enhance reusability.

Usage

  • How It Is Used:
    • Integrated into larger geospatial analysis workflows.
    • Called by other modules or scripts to compute and analyze shoreline and transect statistics.
    • Utilized in environmental monitoring, coastal management, and research projects.

Assumptions

  • Assumptions Made:
    • Input data (transects, shorelines, baseline) are correctly formatted and valid.
    • Earth Engine environment is properly set up and accessible.
    • Constants and utility functions are correctly imported and available.
    • Dates and distances are meaningful and within expected ranges for the analysis.

This comprehensive analysis provides a detailed understanding of the statistics.js module, its functions, and its role within a larger geospatial analysis system.

Flow Diagram [via mermaid]

graph TD
    A[User] -->|provides transects, baseline, shorelines| B[generateTransectsStatistics]
    B -->|calls| C[calculateDistances]
    B -->|calls| D[calculateStatistics]
    B -->|calls| E[complementaryProperties]
    B -->|returns transects with added statistics| F[User]
    G[User] -->|provides transects, shorelines| H[summaryShorelineStatistics]
    H -->|returns shorelines with added statistics| I[User]