genomics/v1/readalignment.proto

// Copyright 2016 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

syntax = "proto3";

package google.genomics.v1;

import "google/api/annotations.proto";
import "google/genomics/v1/cigar.proto";
import "google/genomics/v1/position.proto";
import "google/protobuf/struct.proto";

option cc_enable_arenas = true;
option go_package = "google.golang.org/genproto/googleapis/genomics/v1;genomics";
option java_multiple_files = true;
option java_outer_classname = "ReadAlignmentProto";
option java_package = "com.google.genomics.v1";

// A linear alignment can be represented by one CIGAR string. Describes the
// mapped position and local alignment of the read to the reference.
message LinearAlignment {
  // The position of this alignment.
  Position position = 1;

  // The mapping quality of this alignment. Represents how likely
  // the read maps to this position as opposed to other locations.
  //
  // Specifically, this is -10 log10 Pr(mapping position is wrong), rounded to
  // the nearest integer.
  int32 mapping_quality = 2;

  // Represents the local alignment of this sequence (alignment matches, indels,
  // etc) against the reference.
  repeated CigarUnit cigar = 3;
}

// A read alignment describes a linear alignment of a string of DNA to a
// [reference sequence][google.genomics.v1.Reference], in addition to metadata
// about the fragment (the molecule of DNA sequenced) and the read (the bases
// which were read by the sequencer). A read is equivalent to a line in a SAM
// file. A read belongs to exactly one read group and exactly one
// [read group set][google.genomics.v1.ReadGroupSet].
//
// For more genomics resource definitions, see [Fundamentals of Google
// Genomics](https://cloud.google.com/genomics/fundamentals-of-google-genomics)
//
// ### Reverse-stranded reads
//
// Mapped reads (reads having a non-null `alignment`) can be aligned to either
// the forward or the reverse strand of their associated reference. Strandedness
// of a mapped read is encoded by `alignment.position.reverseStrand`.
//
// If we consider the reference to be a forward-stranded coordinate space of
// `[0, reference.length)` with `0` as the left-most position and
// `reference.length` as the right-most position, reads are always aligned left
// to right. That is, `alignment.position.position` always refers to the
// left-most reference coordinate and `alignment.cigar` describes the alignment
// of this read to the reference from left to right. All per-base fields such as
// `alignedSequence` and `alignedQuality` share this same left-to-right
// orientation; this is true of reads which are aligned to either strand. For
// reverse-stranded reads, this means that `alignedSequence` is the reverse
// complement of the bases that were originally reported by the sequencing
// machine.
//
// ### Generating a reference-aligned sequence string
//
// When interacting with mapped reads, it's often useful to produce a string
// representing the local alignment of the read to reference. The following
// pseudocode demonstrates one way of doing this:
//
//     out = ""
//     offset = 0
//     for c in read.alignment.cigar {
//       switch c.operation {
//       case "ALIGNMENT_MATCH", "SEQUENCE_MATCH", "SEQUENCE_MISMATCH":
//         out += read.alignedSequence[offset:offset+c.operationLength]
//         offset += c.operationLength
//         break
//       case "CLIP_SOFT", "INSERT":
//         offset += c.operationLength
//         break
//       case "PAD":
//         out += repeat("*", c.operationLength)
//         break
//       case "DELETE":
//         out += repeat("-", c.operationLength)
//         break
//       case "SKIP":
//         out += repeat(" ", c.operationLength)
//         break
//       case "CLIP_HARD":
//         break
//       }
//     }
//     return out
//
// ### Converting to SAM's CIGAR string
//
// The following pseudocode generates a SAM CIGAR string from the
// `cigar` field. Note that this is a lossy conversion
// (`cigar.referenceSequence` is lost).
//
//     cigarMap = {
//       "ALIGNMENT_MATCH": "M",
//       "INSERT": "I",
//       "DELETE": "D",
//       "SKIP": "N",
//       "CLIP_SOFT": "S",
//       "CLIP_HARD": "H",
//       "PAD": "P",
//       "SEQUENCE_MATCH": "=",
//       "SEQUENCE_MISMATCH": "X",
//     }
//     cigarStr = ""
//     for c in read.alignment.cigar {
//       cigarStr += c.operationLength + cigarMap[c.operation]
//     }
//     return cigarStr
message Read {
  // The server-generated read ID, unique across all reads. This is different
  // from the `fragmentName`.
  string id = 1;

  // The ID of the read group this read belongs to. A read belongs to exactly
  // one read group. This is a server-generated ID which is distinct from SAM's
  // RG tag (for that value, see
  // [ReadGroup.name][google.genomics.v1.ReadGroup.name]).
  string read_group_id = 2;

  // The ID of the read group set this read belongs to. A read belongs to
  // exactly one read group set.
  string read_group_set_id = 3;

  // The fragment name. Equivalent to QNAME (query template name) in SAM.
  string fragment_name = 4;

  // The orientation and the distance between reads from the fragment are
  // consistent with the sequencing protocol (SAM flag 0x2).
  bool proper_placement = 5;

  // The fragment is a PCR or optical duplicate (SAM flag 0x400).
  bool duplicate_fragment = 6;

  // The observed length of the fragment, equivalent to TLEN in SAM.
  int32 fragment_length = 7;

  // The read number in sequencing. 0-based and less than numberReads. This
  // field replaces SAM flag 0x40 and 0x80.
  int32 read_number = 8;

  // The number of reads in the fragment (extension to SAM flag 0x1).
  int32 number_reads = 9;

  // Whether this read did not pass filters, such as platform or vendor quality
  // controls (SAM flag 0x200).
  bool failed_vendor_quality_checks = 10;

  // The linear alignment for this alignment record. This field is null for
  // unmapped reads.
  LinearAlignment alignment = 11;

  // Whether this alignment is secondary. Equivalent to SAM flag 0x100.
  // A secondary alignment represents an alternative to the primary alignment
  // for this read. Aligners may return secondary alignments if a read can map
  // ambiguously to multiple coordinates in the genome. By convention, each read
  // has one and only one alignment where both `secondaryAlignment`
  // and `supplementaryAlignment` are false.
  bool secondary_alignment = 12;

  // Whether this alignment is supplementary. Equivalent to SAM flag 0x800.
  // Supplementary alignments are used in the representation of a chimeric
  // alignment. In a chimeric alignment, a read is split into multiple
  // linear alignments that map to different reference contigs. The first
  // linear alignment in the read will be designated as the representative
  // alignment; the remaining linear alignments will be designated as
  // supplementary alignments. These alignments may have different mapping
  // quality scores. In each linear alignment in a chimeric alignment, the read
  // will be hard clipped. The `alignedSequence` and
  // `alignedQuality` fields in the alignment record will only
  // represent the bases for its respective linear alignment.
  bool supplementary_alignment = 13;

  // The bases of the read sequence contained in this alignment record,
  // **without CIGAR operations applied** (equivalent to SEQ in SAM).
  // `alignedSequence` and `alignedQuality` may be
  // shorter than the full read sequence and quality. This will occur if the
  // alignment is part of a chimeric alignment, or if the read was trimmed. When
  // this occurs, the CIGAR for this read will begin/end with a hard clip
  // operator that will indicate the length of the excised sequence.
  string aligned_sequence = 14;

  // The quality of the read sequence contained in this alignment record
  // (equivalent to QUAL in SAM).
  // `alignedSequence` and `alignedQuality` may be shorter than the full read
  // sequence and quality. This will occur if the alignment is part of a
  // chimeric alignment, or if the read was trimmed. When this occurs, the CIGAR
  // for this read will begin/end with a hard clip operator that will indicate
  // the length of the excised sequence.
  repeated int32 aligned_quality = 15;

  // The mapping of the primary alignment of the
  // `(readNumber+1)%numberReads` read in the fragment. It replaces
  // mate position and mate strand in SAM.
  Position next_mate_position = 16;

  // A map of additional read alignment information. This must be of the form
  // map<string, string[]> (string key mapping to a list of string values).
  map<string, google.protobuf.ListValue> info = 17;
}