feat: allow annotation from maelstorm cov/mq BED files (#51)

Cargo.toml

@@ -68,3 +68,4 @@ flatc-rust = "0.2.0"
 csv = "1.2.0"
 pretty_assertions = "1.3.0"
 temp_testdir = "0.2.3"
+rstest = "0.17.0"

src/annotate/strucvars/maelstrom.rs

@@ -0,0 +1,209 @@
+//! Code for reading maelstrom coverage and mapping quality VCF files.
+
+use noodles::{
+    core::{Position, Region},
+    vcf,
+};
+use std::ops::Deref;
+use std::{
+    ops::Range,
+    path::{Path, PathBuf},
+};
+
+/// Read access for maelstrom coverage/mapping quality VCF files.
+///
+/// This only works robustly for WGS data.  Also, it is assumed that each VCF
+/// file contains exactly one sample.
+pub struct Reader {
+    /// Path to the VCF file.
+    pub path: PathBuf,
+    /// Name of the single sample in the VCF file.
+    pub sample_name: String,
+    /// The internal reader.
+    pub reader: vcf::IndexedReader<std::fs::File>,
+    /// The header from the VCF file.
+    pub header: vcf::header::Header,
+}
+
+impl Reader {
+    /// Construct reader with given path and sample name.
+    ///
+    /// The VCF file at `p` must have an index.
+    ///
+    /// # Arguments
+    ///
+    /// * `p` - Path to the tabix indexed and bgzip-compressed VCF file.
+    pub fn from_path<P>(p: P) -> Result<Self, anyhow::Error>
+    where
+        P: AsRef<Path> + Clone,
+    {
+        let path = p.as_ref().to_path_buf();
+        let mut reader = vcf::indexed_reader::Builder::default().build_from_path(&path)?;
+        let header = reader.read_header()?;
+        let header: vcf::header::Header = header.parse()?;
+        let sample = if header.sample_names().len() == 1 {
+            header
+                .sample_names()
+                .iter()
+                .next()
+                .expect("just checked for ==1 sample")
+                .clone()
+        } else {
+            anyhow::bail!(
+                "VCF file {} must contain exactly one sample",
+                p.as_ref().display()
+            );
+        };
+
+        Ok(Self {
+            path,
+            sample_name: sample,
+            reader,
+            header,
+        })
+    }
+
+    /// Read coverage and mapping quality for given range and compute means.
+    ///
+    /// # Arguments
+    ///
+    /// * `chrom` - Chromosome name.
+    /// * `range` - 1-based range to read on `chrom`.
+    ///
+    /// # Returns
+    ///
+    /// The mean coverage and mean mapping quality bundled into one `Record`.
+    pub fn read(&mut self, chrom: &str, range: Range<i32>) -> Result<Record, anyhow::Error> {
+        // Jump to the given region.
+        let start: usize = range.start.try_into()?;
+        let pos_start = Position::try_from(start)?;
+        let end: usize = range.end.try_into()?;
+        let pos_end = Position::try_from(end)?;
+        let region = Region::new(chrom, pos_start..=pos_end);
+        let query = self.reader.query(&self.header, &region)?;
+
+        // Read in the records and compute the mean coverage and mapping quality.  The records
+        // describe the mean statistics over a window.  We go all the way to compute fractions
+        // of windows.
+        let mut cov_sum = 0f64;
+        let mut mq_sum = 0f64;
+        let mut count = 0f64;
+
+        for result in query {
+            let record = result?;
+
+            let window_end = record.info().get(&vcf::header::info::key::END_POSITION);
+            use vcf::record::info::field::Value::Integer;
+            let window_end = if let Some(Some(Integer(window_end))) = window_end {
+                *window_end as usize
+            } else {
+                anyhow::bail!("missing INFO/END in record");
+            };
+            let window_start: usize = record.position().into();
+            let window_size = window_end - window_start + 1;
+
+            // Use first and last window values only in fractions.
+            let covered = if window_start < start {
+                window_size - (start - window_start)
+            } else if window_end > end {
+                window_size - (window_end - end)
+            } else {
+                window_size
+            };
+            let covered: i32 = covered.try_into()?;
+            let covered: f64 = covered.try_into()?;
+            let window_size: i32 = window_size.try_into()?;
+            let window_size: f64 = window_size.try_into()?;
+            let factor = covered / window_size;
+            count += factor;
+
+            let genotype = record
+                .genotypes()
+                .deref()
+                .iter()
+                .next()
+                .expect("just checked for ==1 sample");
+
+            // The simplest way to obtain the genotype keys is to iterate and call `as_ref()` on the
+            // key.
+            for (key, value) in genotype.deref().iter() {
+                match (key.as_ref(), value) {
+                    ("CV", Some(vcf::record::genotypes::genotype::field::Value::Float(cov))) => {
+                        cov_sum += factor * (*cov) as f64;
+                    }
+                    ("MQ", Some(vcf::record::genotypes::genotype::field::Value::Float(mq))) => {
+                        mq_sum += factor * (*mq) as f64;
+                    }
+                    // Ignore all other keys.
+                    _ => (),
+                }
+            }
+        }
+
+        Ok(if count > 0f64 {
+            Record {
+                mean_coverage: cov_sum / count,
+                mean_mapq: mq_sum / count,
+            }
+        } else {
+            Default::default()
+        })
+    }
+}
+
+/// Result for `Reader::read`.
+#[derive(Debug, Default, Clone, PartialEq)]
+pub struct Record {
+    /// Mean quality.
+    pub mean_coverage: f64,
+    /// Mean mapping quality.
+    pub mean_mapq: f64,
+}
+
+#[cfg(test)]
+mod test {
+    use super::Reader;
+    use pretty_assertions::assert_eq;
+
+    #[test]
+    fn reader_from_path() -> Result<(), anyhow::Error> {
+        let path = "tests/data/annotate/strucvars/maelstrom/example.SAMPLE.cov.vcf.gz";
+        let reader = Reader::from_path(path)?;
+        assert_eq!(reader.sample_name, "SAMPLE");
+        assert_eq!(format!("{}", reader.path.display()), path);
+
+        Ok(())
+    }
+
+    #[test]
+    fn reader_read() -> Result<(), anyhow::Error> {
+        let path = "tests/data/annotate/strucvars/maelstrom/example.SAMPLE.cov.vcf.gz";
+        let mut reader = Reader::from_path(path)?;
+
+        {
+            let record = reader.read("1", 10_001..20_000)?;
+            assert_eq!(record.mean_coverage, 1.0);
+            assert_eq!(record.mean_mapq, 40.0);
+        }
+
+        {
+            let record = reader.read("1", 10_501..20_000)?;
+            assert_eq!(record.mean_coverage, 1.0);
+            assert_eq!(record.mean_mapq, 40.0);
+        }
+
+        {
+            let record = reader.read("1", 10_001..19_500)?;
+            assert_eq!(record.mean_coverage, 1.0);
+            assert_eq!(record.mean_mapq, 40.0);
+        }
+
+        {
+            let record = reader.read("1", 10_501..19_500)?;
+            assert_eq!(record.mean_coverage, 1.0);
+            assert_eq!(record.mean_mapq, 40.0);
+        }
+
+        Ok(())
+    }
+}