wigToBigWig

WigToBigWig is a command-line utility from the UCSC Genome Utilities toolkit that converts Wiggle (WIG) format files into BigWig (BW) binary format. BigWig files provide indexed, compressed data suitable for fast random access, making them well suited for visualization in genome browsers and for downstream analysis.

Input and output requirements: WigToBigWig takes a WIG file as input and relies on a chromosome sizes file (chrom.sizes) that lists chromosome names and their lengths. The chrom.sizes file is required so the converter can map coordinates accurately and allocate the proper data structure in the resulting BigWig. The tool supports standard WIG formats, including fixedStep, variableStep, and bedGraph-like blocks, and outputs a single .bw file.

Usage example: wigToBigWig input.wig chrom.sizes output.bw. The program is part of the UCSC Kent source distribution and is typically built against the Kent libraries; users may need to ensure the libBigWig library (or equivalent) is available during build and installation. After conversion, the resulting BigWig file can be loaded into genome browsers for efficient visualization over large genomic regions.

Notes and considerations: The conversion preserves the values described in the WIG file and encodes them in a format that supports rapid querying of any genomic interval. WigToBigWig is widely used in workflows that require efficient data access and sharing, particularly when working with large continuous signal tracks such as coverage, read depth, or other genome-wide measurements. It is one of several utilities in the UCSC toolkit designed to interconvert discreet and binary genomic data formats.