samtools_idxstats

samtools_idxstats reports per-reference alignment statistics from indexed BAM files, summarizing mapped and unmapped read counts to evaluate sequencing coverage and data quality.

Key Features:

• Indexing support: Operates on indexed BAM files using SAMtools indexes to enable efficient random access to alignment data.
• Per-reference alignment counts: Outputs counts of mapped and unmapped reads for each reference sequence present in the BAM file.
• Format compatibility: Works with SAM/BAM formats and leverages SAM-format conventions for storing read alignments, including support for large reads up to 128 Mbp.
• Data handling efficiency: Produces compact summary output that facilitates rapid retrieval and aggregation of alignment statistics across large datasets.

Scientific Applications:

• Quality control: Verifies the number of reads aligned to each reference sequence to detect library- or sequencing-related issues.
• Coverage assessment: Provides per-reference counts useful for assessing coverage depth across reference sequences.
• High-throughput data management: Summarizes alignment metrics for large-scale sequencing projects (e.g., 1000 Genomes Project) to support dataset filtering and tracking.

Methodology:

Parses indexed BAM files to extract per-reference alignment statistics, leveraging SAMtools indexing to allow rapid retrieval and analysis of specific genomic regions or entire datasets.