js-array-filter

js-array-filter is a TypeScript library for filtering arrays based on conditions. It provides functionalities to define filters and apply them to arrays of data.

Features

• Define filters with multiple conditions and connectors
• Apply filters to arrays of data
• Support for various data types and operators
• Compare with variables (e.g., VAR1 = VAR2).
• Condition priority for complex expressions.

Installation

Install the library using npm:

npm install js-array-filter

Usage

Creating a Filter instance

importFilterfrom'js-array-filter';constcolumns=[{name: 'AGE',dataType: 'number'},{name: 'SEX',dataType: 'string'}];constfilter=newFilter('parsed',columns,{conditions: [{variable: 'AGE',operator: 'gt',value: 80},{variable: 'SEX',operator: 'eq',value: 'M'}],connectors: ['and']});

Creating a Filter instance from a string

importFilterfrom'js-array-filter';constcolumns=[{name: 'AGE',dataType: 'number'},{name: 'SEX',dataType: 'string'}];constfilterString="AGE gt 80 and SEX eq 'M'";constfilter=newFilter('parsed',columns,filterString);

Applying the Filter

constdata=[[85,'M'],[70,'F'],[90,'M']];constfilteredData=data.filter(row=>filter.filterRow(row));console.log(filteredData);// Output: [[85, 'M'], [90, 'M']]

Applying the Filter to a Dataframe

constdata=[[85,'M'],[70,'F'],[90,'M']];constfilteredData=filter.filterDataframe(data);console.log(filteredData);// Output: [[85, 'M'], [90, 'M']]

Updating the Filter

filter.update({conditions: [{variable: 'AGE',operator: 'lt',value: 75}],connectors: []});constnewFilteredData=data.filter(row=>filter.filterRow(row));console.log(newFilteredData);// Output: [[70, 'F']]

Converting Filter to String

constfilterString=filter.toString();console.log(filterString);

Validating Filter String

constisValid=filter.validateFilterString(filterString);console.log(isValid);// Output: true or false

Comparing with a variable

importFilterfrom'js-array-filter';constcolumns=[{name: 'AVAL',dataType: 'number'},{name: 'BASE',dataType: 'number'}];// AVAL > BASEconstfilter=newFilter('parsed',columns,{conditions: [{variable: 'AVAL',operator: 'gt',value: null,compareVariable: 'BASE'},],connectors: []});

Condition priority

// (AGE > 80 and SEX = "M") or (AGE > 60 and SEX = "F")constfilter=newFilter('parsed',columns,{conditions: [{variable: 'AGE',operator: 'gt',value: 80},{variable: 'SEX',operator: 'eq',value: 'M'},{variable: 'AGE',operator: 'gt',value: 60},{variable: 'SEX',operator: 'eq',value: 'F'}],connectors: ['and','or','and'],connectorPriorities: [1,0,1]});

Operators

String Operators

• lt: Less than
• le: Less than or equal to
• gt: Greater than
• ge: Greater than or equal to
• in: In array
• notin: Not in array
• eq: Equal to
• ne: Not equal to
• starts: Starts with
• ends: Ends with
• contains: Contains
• notcontains: Does not contain
• regex: Matches regular expression
• notMissing: Not missing (not null or empty)
• missing: Missing (null or empty)

Number Operators

• lt: Less than
• le: Less than or equal to
• gt: Greater than
• ge: Greater than or equal to
• in: In array
• notin: Not in array
• eq: Equal to
• ne: Not equal to
• notMissing: Not missing (not null or empty)
• missing: Missing (null or empty)

Boolean Operators

• eq: Equal to
• ne: Not equal to
• notMissing: Not missing (not null or empty)
• missing: Missing (null or empty)

Methods

update

Updates the filter with new filter and columns.

Parameters

• filter (BasicFilter | string): The new filter object or filter string.
• columns (ColumnMetadata[], optional): The new column metadata.

filterRow

Applies the filter to a single row of data.

Parameters

• row (ItemDataArray): The row of data to filter.

Returns

• boolean: True if the row passes the filter, false otherwise.

filterDataframe

Applies the filter to a dataframe (array of rows).

Parameters

• data (ItemDataArray[]): The dataframe to filter.

Returns

• ItemDataArray[]: The filtered dataframe.

toString

Converts the filter to a string representation.

Returns

• string: The string representation of the filter.

validateFilterString

Validates a filter string.

Parameters

• filterString (string): The filter string to validate.

Returns

• boolean: True if the filter string is valid, false otherwise.

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Running Tests

Run the tests using Jest:

npm test

License

This project is licensed under the MIT License. See the LICENSE file for details.

Author

Dmitry Kolosov

Contributing

Open an issue or submit a pull request for any improvements or bug fixes.

For more details, refer to the source code and the documentation.