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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]
```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]
```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]
```