js-stream-sas7bdat

js-stream-sas7bdat is a TypeScript library for streaming and processing SAS7BDAT files in Node.js environment. It provides functionalities to read data and metadata from SAS7BDAT files using ReadStat library. The output format matches CDISC Dataset-JSON 1.1 format.

Features

• Stream SAS7BDAT files
• Extract metadata from SAS7BDAT files
• Read observations as an iterable
• Get unique values from observations
• Filter data

Installation

Install the library using npm:

npm install js-stream-sas7bdat

Building Node extension

To build the node native extension:

npm run build

To build on Windows, it is required to compile libiconv outside of this project and place iconv.h to src/binding/libiconv/include and 32-bit and 64-bit versions of libiconv.lib in folders /src/binding/libiconv/x32/ and /src/binding/libiconv/x64/.

The project includes prebuild binaries which were tested for Linux x64 and Windows x64.

Usage

dataset = new DatasetSas7BDat(filePath, [options])

Creating Dataset-SAS7BDAT instance

import DatasetSas7BDat from 'js-stream-sas7bdat';

dataset = new DatasetSas7BDat('/path/to/dataset.sas7bdat')

Example

const dataset = new DatasetSas7BDat('/path/to/dataset.sas7bdat');

Getting Metadata

const metadata = await dataset.getMetadata();

Reading Observations

// Read first 500 records of a dataset
const data = await dataset.getData({start: 0, length: 500})

Reading Observations as iterable

// Read dataset starting from position 10 (11th record in the dataset)
for await (const record of dataset.readRecords({start: 10, filterColumns: ["studyId", "uSubjId"], type: "object"})) {
    console.log(record);
}

Getting Unique Values

const uniqueValues = await dataset.getUniqueValues({ columns: ["studyId", "uSubjId"], limit: 100 });

Applying Filters

You can apply filters to the data when reading observations using the js-array-filter package.

Example

import Filter from 'js-array-filter';

// Define a filter
const filter = new Filter('dataset-json1.1', metadata.columns, {
    conditions: [
        { variable: 'AGE', operator: 'gt', value: 55 },
        { variable: 'DCDECOD', operator: 'eq', value: 'STUDY TERMINATED BY SPONSOR' }
    ],
    connectors: ['or']
});

// Apply the filter when reading data
const filteredData = dataset.getData({
    start: 0,
    filter: filter,
    filterColumns: ['USUBJID', 'DCDECOD', 'AGE']
});
console.log(filteredData);

Methods

getMetadata

Returns the metadata of the SAS7BDAT file.

Returns

• Promise<Metadata>: A promise that resolves to the metadata of the dataset.

Example

const metadata = await dataset.getMetadata();
console.log(metadata);

getData

Reads observations from the dataset.

Parameters

• props (object): An object containing the following properties:
  • start (number, optional): The starting position for reading data.
  • length (number, optional): The number of records to read. Defaults to reading all records.
  • type (DataType, optional): The type of the returned object ("array" or "object"). Defaults to "array".
  • filterColumns (string[], optional): The list of columns to return when type is "object". If empty, all columns are returned.
  • filter (Filter, optional): A Filter instance from js-array-filter package used to filter data records.
  • dynamicLength (boolean, optional): When using a filter, this will dynamically adjust chunk size to optimize performance. Defaults to false.

Returns

• Promise<(ItemDataArray | ItemDataObject)[]>: A promise that resolves to an array of data records.

Example

const data = await dataset.getData({ start: 0, length: 500, type: "object", filterColumns: ["studyId", "uSubjId"] });
console.log(data);

readRecords

Reads observations as an iterable.

Parameters

• props (object, optional): An object containing the following properties:
  • start (number, optional): The starting position for reading data. Defaults to 0.
  • bufferLength (number, optional): The number of records to read in each chunk. Defaults to 1000.
  • type (DataType, optional): The type of data to return ("array" or "object"). Defaults to "array".
  • filterColumns (string[], optional): An array of column names to include in the returned data.
  • dynamicLength (boolean, optional): When using a filter, this will dynamically adjust chunk size to optimize performance. Defaults to false.

Returns

• AsyncGenerator<ItemDataArray | ItemDataObject, void, undefined>: An async generator that yields data records.

Example

for await (const record of dataset.readRecords({ start: 10, filterColumns: ["studyId", "uSubjId"], type: "object" })) {
    console.log(record);
}

getUniqueValues

Gets unique values for variables.

Parameters

• props (object): An object containing the following properties:
  • columns (string[]): An array of column names to get unique values for.
  • limit (number, optional): The maximum number of unique values to return for each column. Defaults to 100.
  • bufferLength (number, optional): The buffer length for reading data. Defaults to 1000.
  • sort (boolean, optional): Whether to sort the unique values. Defaults to true.

Returns

• Promise<UniqueValues>: A promise that resolves to an object containing unique values for the specified columns.

Example

const uniqueValues = await dataset.getUniqueValues({
    columns: ["studyId", "uSubjId"],
    limit: 100,
    bufferLength: 1000,
    sort: true
});
console.log(uniqueValues);

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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

Contributions are welcome! Please 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.