Task: Data Processor with Strategy Pattern

Objective

You will implement a data processing pipeline using the Strategy Pattern. The pipeline will:

1. Clean the input data using a chosen cleaning strategy,
2. Analyze the cleaned data using one of five analysis strategies,
3. Output the result to either the console or a text file.

Your job is to implement one method that ties these strategies together.

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Method Signature

public double process(
    CleaningType cleaningType,
    AnalysisType analysisType,
    OutputType outputType,
    List<Integer> data
) throws Exception

• Parameters:

  • cleaningType → which cleaning strategy to use
  • analysisType → which analysis to perform
  • outputType → where to send the result (console or file)
  • data → the list of integers to process

• Return:

  • The numeric result of the chosen analysis as a double.

• Order of operations: Clean → Analyze → Output → Return result

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Cleaning Strategies

• REMOVE_NEGATIVES: drop all values < 0
• REPLACE_NEGATIVES_WITH_ZERO: replace all values < 0 with 0

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Analysis Strategies (5 Total)

1. MEAN

   • Arithmetic average of all numbers.
   • Empty list → NaN.

2. MEDIAN

   • Middle value after sorting (even length → average of two middles).
   • Empty list → NaN.

3. STD_DEV

   • Population standard deviation (divide by N, not N−1).
   • Empty list → NaN.

4. P90_NEAREST_RANK

   • Sort ascending; rank = ceil(0.90 * N) (1-based); return value at that rank.
   • Empty list → NaN.

5. TOP3_FREQUENT_COUNT_SUM

   • Count frequencies of each distinct value.
   • Sort by count desc, break ties by value asc.
   • Take the top 3 frequencies and sum them (fewer than 3 → sum existing).
   • Empty list → 0.0.

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Output Strategies

• CONSOLE: Print Result = <value> to standard output.

• TEXT_FILE: Write Result = <value> to target/result.txt.

  • Overwrite if file exists.
  • Create directories if needed.

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Rules

• Use the Strategy Pattern and the provided factory; no long if/else ladders.
• Do not modify the input list directly.
• Handle empty input according to the rules above.
• Write output exactly in the format Result = <value>.

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Examples

CleaningType	AnalysisType	OutputType	Input Data	Result
REMOVE_NEGATIVES	MEAN	CONSOLE	[5, -2, 7, 8]	Mean = 6.666…
REPLACE_NEGATIVES_WITH_ZERO	MEDIAN	TEXT_FILE	[5, -2, 7, 8]	Median = 6.0
REMOVE_NEGATIVES	P90_NEAREST_RANK	CONSOLE	[1,3,5,7,9,11,13,15,17,19]	17.0
REPLACE_NEGATIVES_WITH_ZERO	STD_DEV	TEXT_FILE	[2,4,4,4,5,5,7,9]	StdDev = 2.0
REMOVE_NEGATIVES	TOP3_FREQUENT_COUNT_SUM	CONSOLE	[5,5,5,1,1,2,2,3]	Count sum = 7.0

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