README.md

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

Installation

Install the library using npm:

npm install js-array-filter

Usage

Creating a Filter instance

import Filter from 'js-array-filter';

const columns = [
    { name: 'AGE', dataType: 'number' },
    { name: 'SEX', dataType: 'string' }
];

const filter = new Filter('parsed', columns, {
    conditions: [
        { variable: 'AGE', operator: 'gt', value: 80 },
        { variable: 'SEX', operator: 'eq', value: 'M' }
    ],
    connectors: ['and']
});

Creating a Filter instance from a string

import Filter from 'js-array-filter';

const columns = [
    { name: 'AGE', dataType: 'number' },
    { name: 'SEX', dataType: 'string' }
];

const filterString = "AGE gt 80 and SEX eq 'M'";
const filter = new Filter('parsed', columns, filterString);

Applying the Filter

const data = [
    [85, 'M'],
    [70, 'F'],
    [90, 'M']
];

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

Applying the Filter to a Dataframe

const data = [
    [85, 'M'],
    [70, 'F'],
    [90, 'M']
];

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

Updating the Filter

filter.update({
    conditions: [
        { variable: 'AGE', operator: 'lt', value: 75 }
    ],
    connectors: []
});

const newFilteredData = data.filter(row => filter.filterRow(row));
console.log(newFilteredData); // Output: [[70, 'F']]

Converting Filter to String

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

Validating Filter String

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

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.