Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
minimap2(1)		     Bioinformatics tools		   minimap2(1)

NAME
       minimap2	- mapping and alignment	between	collections of DNA sequences

SYNOPSIS
       * Indexing the target sequences (optional):
	   minimap2 [-x	preset]	-d target.mmi target.fa
	   minimap2  [-H]  [-k	kmer]  [-w miniWinSize]	[-I batchSize] -d tar-
	   get.mmi target.fa

       * Long-read alignment with CIGAR:
	   minimap2 -a [-x preset] target.mmi query.fa > output.sam
	   minimap2 -c	[-H]  [-k  kmer]  [-w  miniWinSize]  [...]   target.fa
	   query.fa > output.paf

       * Long-read overlap without CIGAR:
	   minimap2 -x ava-ont [-t nThreads] target.fa query.fa	> output.paf

DESCRIPTION
       Minimap2	is a fast sequence mapping and alignment program that can find
       overlaps	between	long noisy reads, or map long reads  or	 their	assem-
       blies  to  a  reference genome optionally with detailed alignment (i.e.
       CIGAR). At present, it works efficiently	with query  sequences  from  a
       few  kilobases  to  ~100	megabases in length at a error rate ~15%. Min-
       imap2 outputs in	the PAF	or the SAM format.

OPTIONS
   Indexing options
       -k INT	 Minimizer k-mer length	[15]

       -w INT	 Minimizer window size [2/3 of k-mer length]. A	 minimizer  is
		 the smallest k-mer in a window	of w consecutive k-mers.

       -H	 Use  homopolymer-compressed (HPC) minimizers. An HPC sequence
		 is constructed	by contracting homopolymer runs	 to  a	single
		 base. An HPC minimizer	is a minimizer on the HPC sequence.

       -I NUM	 Load  at most NUM target bases	into RAM for indexing [4G]. If
		 there are more	than NUM bases in target.fa, minimap2 needs to
		 read  query.fa	multiple times to map it against each batch of
		 target	sequences.  NUM	may be ending  with  k/K/m/M/g/G.  NB:
		 mapping quality is incorrect given a multi-part index.

       --idx-no-seq
		 Don't	store  target  sequences  in  the index. It saves disk
		 space and memory but the index	 generated  with  this	option
		 will  not  work  with -a or -c.  When base-level alignment is
		 not requested,	this option is automatically applied.

       -d FILE	 Save the minimizer index of target.fa to FILE [no dump]. Min-
		 imap2	indexing  is  fast. It can index the human genome in a
		 couple	of minutes. If even shorter startup time  is  desired,
		 use this option to save the index. Indexing options are fixed
		 in the	index file. When an index file is provided as the tar-
		 get  sequences,  options  -H,	-k, -w,	-I will	be effectively
		 overridden by the options stored in the index file.

   Mapping options
       -f FLOAT|INT1[,INT2]
		 If fraction, ignore top FLOAT fraction	of most	frequent mini-
		 mizers	 [0.0002]. If integer, ignore minimizers occuring more
		 than INT1 times.  INT2	is only	effective in the --sr or  -xsr
		 mode, which sets the threshold	for a second round of seeding.

       --min-occ-floor INT
		 Force	minimap2  to  always use k-mers	occurring INT times or
		 less [0]. In effect, the max occurrence threshold is  set  to
		 the max{INT, -f}.

       -g INT	 Stop chain enlongation	if there are no	minimizers within INT-
		 bp [10000].

       -r INT	 Bandwidth used	in chaining and	DP-based alignment [500]. This
		 option	approximately controls the maximum gap size.

       -n INT	 Discard chains	consisting of <INT number of minimizers	[3]

       -m INT	 Discard  chains with chaining score <INT [40].	Chaining score
		 equals	the approximate	number of matching bases minus a  con-
		 cave gap penalty. It is computed with dynamic programming.

       -D	 If  query  sequence  name/length  are identical to the	target
		 name/length, ignore diagonal anchors. This  option  also  re-
		 duces DP-based	extension along	the diagonal.

       -P	 Retain	 all  chains  and don't	attempt	to set primary chains.
		 Options -p and	-N have	no effect when this option is in use.

       --dual=yes|no
		 If no,	skip query-target pairs	wherein	the query name is lex-
		 icographically	greater	than the target	name [yes]

       -X	 Equivalent to '-DP --dual=no --no-long-join'.	Primarily used
		 for all-vs-all	read overlapping.

       -p FLOAT	 Minimal secondary-to-primary score ratio to output  secondary
		 mappings  [0.8].   Between two	chains overlaping over half of
		 the shorter chain (controlled by -M), the chain with a	 lower
		 score	is secondary to	the chain with a higher	score.	If the
		 ratio of the scores is	below FLOAT, the secondary chain  will
		 not  be  outputted or extended	with DP	alignment later.  This
		 option	has no effect when -X is applied.

       -N INT	 Output	at most	INT secondary alignments [5]. This option  has
		 no effect when	-X is applied.

       -G NUM	 Maximum   gap	 on   the   reference	(effective  with  -xs-
		 plice/--splice).  This	option also changes the	 chaining  and
		 alignment  band  width	 to NUM.  Increasing this option slows
		 down spliced alignment. [200k]

       -F NUM	 Maximum fragment length  (aka	insert	size;  effective  with
		 -xsr/--frag=yes) [800]

       -M FLOAT	 Mark  as  secondary a chain that overlaps with	a better chain
		 by FLOAT or more of the shorter chain [0.5]

       --hard-mask-level
		 Honor option -M and disable a heurstic	to save	unmapped  sub-
		 sequences.

       --max-chain-skip	INT
		 A  heuristics	that  stops chaining early [25]. Minimap2 uses
		 dynamic programming for chaining. The time complexity is qua-
		 dratic	in the number of seeds.	This option makes minimap2 ex-
		 its the inner loop if it repeatedly  sees  seeds  already  on
		 chains.  Set  INT  to	a  large  number  to  switch  off this
		 heurstics.

       --max-chain-iter	INT
		 Check up to INT partial chains	during chaining	 [5000].  This
		 is  a	heuristic  to  avoid  quadratic	time complexity	in the
		 worst case.

       --no-long-join
		 Disable the long gap patching heuristic. When this option  is
		 applied,  the	maximum	 alignment gap is mostly controlled by
		 -r.

       --lj-min-ratio FLOAT
		 Fraction of query sequence length required to bridge  a  long
		 gap  [0.5].  A	smaller	value helps to recover longer gaps, at
		 the cost of more false	gaps.

       --splice	 Enable	the splice alignment mode.

       --sr	 Enable	short-read alignment  heuristics.  In  the  short-read
		 mode,	minimap2  applies  a  second  round of chaining	with a
		 higher	minimizer occurrence threshold if  no  good  chain  is
		 found.	 In  addition, minimap2	attempts to patch gaps between
		 seeds with ungapped alignment.

       --split-prefix STR
		 Prefix	to create temporary files. Typically used for a	multi-
		 part index.

       --frag=no|yes
		 Whether to enable the fragment	mode [no]

       --for-only
		 Only  map  to	the forward strand of the reference sequences.
		 For paired-end	reads in the forward-reverse orientation,  the
		 first	read  is mapped	to forward strand of the reference and
		 the second read to the	reverse	stand.

       --rev-only
		 Only map to the reverse complement strand  of	the  reference
		 sequences.

       --heap-sort=no|yes
		 If  yes, sort anchors with heap merge,	instead	of radix sort.
		 Heap merge is faster for short	reads,	but  slower  for  long
		 reads.	[no]

       --no-pairing
		 Treat	two reads in a pair as independent reads. The mate re-
		 lated fields in SAM are still properly	populated.

   Alignment options
       -A INT	 Matching score	[2]

       -B INT	 Mismatching penalty [4]

       -O INT1[,INT2]
		 Gap open penalty [4,24]. If INT2 is not specified, it is  set
		 to INT1.

       -E INT1[,INT2]
		 Gap  extension	 penalty  [2,1].  A  gap  of  length  k	 costs
		 min{O1+k*E1,O2+k*E2}.	In the splice  mode,  the  second  gap
		 penalties are not used.

       -C INT	 Cost  for  a  non-canonical  GT-AG  splicing  (effective with
		 --splice) [0]

       -z INT1[,INT2]
		 Truncate an alignment if the running  alignment  score	 drops
		 too  quickly along the	diagonal of the	DP matrix (diagonal X-
		 drop, or Z-drop) [400,200]. If	the drop  of  score  is	 above
		 INT2,	minimap2  will reverse complement the query in the re-
		 lated region and align	again to test small  inversions.  Min-
		 imap2	truncates  alignment  if  there	is an inversion	or the
		 drop of score is greater than INT1.  Decrease	INT2  to  find
		 small	inversions  at the cost	of performance and false posi-
		 tives.	 Increase INT1 to improves the contiguity of alignment
		 at the	cost of	poor alignment in the middle.

       -s INT	 Minimal  peak	DP  alignment  score  to output	[40]. The peak
		 score is computed from	the final CIGAR. It is	the  score  of
		 the max scoring segment in the	alignment and may be different
		 from the total	alignment score.

       -u CHAR	 How to	find canonical splicing	sites GT-AG  -	f:  transcript
		 strand; b: both strands; n: no	attempt	to match GT-AG [n]

       --end-bonus INT
		 Score	bonus  when  alignment extends to the end of the query
		 sequence [0].

       --score-N INT
		 Score of a mismatch involving ambiguous bases [1].

       --splice-flank=yes|no
		 Assume	the next base to a GT donor site tends to be A/G  (91%
		 in human and 92% in mouse) and	the preceding base to a	AG ac-
		 ceptor	tends to be C/T	[no].  This  trend  is	evolutionarily
		 conservative,	all  the way to	S. cerevisiae (PMID:18688272).
		 Specifying this option	generally leads	to higher junction ac-
		 curacy	 by several percents, so it is applied by default with
		 --splice.  However, the SIRV  control	does  not  honor  this
		 trend	(only  ~60%). This option reduces accuracy. If you are
		 benchmarking minimap2 on  SIRV	 data,	please	add  --splice-
		 flank=no to the command line.

       --junc-bed FILE
		 Gene  annotations in the BED12	format (aka 12-column BED), or
		 intron	positions in 5-column BED. With	this option,  minimap2
		 prefers splicing in annotations.  BED12 file can be converted
		 from GTF/GFF3 with `paftools.js gff2bed anno.gtf' [].

       --junc-bonus INT
		 Score bonus for a splice donor	or acceptor found  in  annota-
		 tion (effective with --junc-bed) [0].

       --end-seed-pen INT
		 Drop  a terminal anchor if s<log(g)+INT, where	s is the local
		 alignment score around	the anchor and g  the  length  of  the
		 terminal gap in the chain. This option	is only	effective with
		 --splice.  It helps to	avoid tiny terminal exons. [6]

       --no-end-flt
		 Don't filter seeds towards the	ends of	chains before perform-
		 ing base-level	alignment.

       --cap-sw-mem NUM
		 Skip  alignment if the	DP matrix size is above	NUM.  Set 0 to
		 disable [0].

   Input/output	options
       -a	 Generate CIGAR	and output alignments in the SAM format.  Min-
		 imap2 outputs in PAF by default.

       -o FILE	 Output	alignments to FILE [stdout].

       -Q	 Ignore	base quality in	the input file.

       -L	 Write	CIGAR with >65535 operators at the CG tag. Older tools
		 are unable to convert alignments with	>65535	CIGAR  ops  to
		 BAM.  This  option  makes  minimap2 SAM compatible with older
		 tools.	Newer tools recognizes this tag	 and  reconstruct  the
		 real CIGAR in memory.

       -R STR	 SAM read group	line in	a format like @RG\tID:foo\tSM:bar [].

       -y	 Copy input FASTA/Q comments to	output.

       -c	 Generate CIGAR. In PAF, the CIGAR is written to the `cg' cus-
		 tom tag.

       --cs[=STR]
		 Output	the cs tag.  STR can be	either short or	long.	If  no
		 STR is	given, short is	assumed. [none]

       --MD	 Output	the MD tag (see	the SAM	spec).

       --eqx	 Output	=/X CIGAR operators for	sequence match/mismatch.

       -Y	 In  SAM  output,  use	soft clipping for supplementary	align-
		 ments.

       --seed INT
		 Integer seed for  randomizing	equally	 best  hits.  Minimap2
		 hashes	 INT  and read name when choosing between equally best
		 hits. [11]

       -t INT	 Number	of threads [3].	Minimap2 uses at  most	three  threads
		 when  indexing	target sequences, and uses up to INT+1 threads
		 when mapping (the extra thread	is  for	 I/O,  which  is  fre-
		 quently idle and takes	little CPU time).

       -2	 Use two I/O threads during mapping. By	default, minimap2 uses
		 one I/O thread.  When I/O is slow (e.g. piping	 to  gzip,  or
		 reading from a	slow pipe), the	I/O thread may become the bot-
		 tleneck. Apply	this option to use one thread  for  input  and
		 another thread	for output, at the cost	of increased peak RAM.

       -K NUM	 Number	of bases loaded	into memory to process in a mini-batch
		 [500M].  Similar to option  -I,  K/M/G/k/m/g  suffix  is  ac-
		 cepted. A large NUM helps load	balancing in the multi-thread-
		 ing mode, at the cost of increased memory.

       --secondary=yes|no
		 Whether to output secondary alignments	[yes]

       --max-qlen NUM
		 Filter	out query sequences longer than	NUM.

       --paf-no-hit
		 In PAF, output	unmapped queries; the strand and the reference
		 name  fields  are  set	to `*'.	Warning: some paftools.js com-
		 mands may not work with such output for the moment.

       --sam-hit-only
		 In SAM, don't output unmapped reads.

       --version Print version number to stdout

   Preset options
       -x STR	 Preset	[]. This option	applies	multiple options at  the  same
		 time.	It  should be applied before other options because op-
		 tions applied later will overwrite  the  values  set  by  -x.
		 Available STR are:

		 map-pb	 PacBio/Oxford	Nanopore  read	to  reference  mapping
			 (-Hk19)

		 map-ont Slightly more sensitive for Oxford Nanopore to	refer-
			 ence  mapping (-k15).	For PacBio reads, HPC minimiz-
			 ers consistently leads	to faster performance and more
			 sensitive results in comparison to normal minimizers.
			 For Oxford Nanopore data, normal minimizers are  bet-
			 ter, though not much. The effectiveness of HPC	is de-
			 termined by the sequencing error mode.

		 asm5	 Long assembly to reference  mapping  (-k19  -w19  -A1
			 -B19	-O39,81	 -E3,1	-s200  -z200  -N50  --min-occ-
			 floor=100).  Typically, the alignment will not	extend
			 to  regions  with  5%	or higher sequence divergence.
			 Only use this preset if the average divergence	is far
			 below 5%.

		 asm10	 Long assembly to reference mapping (-k19 -w19 -A1 -B9
			 -O16,41 -E2,1 -s200 -z200 -N50	 --min-occ-floor=100).
			 Up to 10% sequence divergence.

		 asm20	 Long assembly to reference mapping (-k19 -w10 -A1 -B4
			 -O6,26	-E2,1 -s200 -z200  -N50	 --min-occ-floor=100).
			 Up to 20% sequence divergence.

		 ava-pb	 PacBio	 all-vs-all  overlap mapping (-Hk19 -Xw5 -m100
			 -g10000 --max-chain-skip 25).

		 ava-ont Oxford	Nanopore all-vs-all overlap mapping (-k15 -Xw5
			 -m100	-g10000	 -r2000	 --max-chain-skip  25).	 Simi-
			 larly,	the major difference from ava-pb is that  this
			 preset	is not using HPC minimizers.

		 splice	 Long-read spliced alignment (-k15 -w5 --splice	-g2000
			 -G200k	-A1 -B2	-O2,32 -E1,0  -C9  -z200  -ub  --junc-
			 bonus=9  --splice-flank=yes).	In the splice mode, 1)
			 long deletions	are taken as introns  and  represented
			 as  the  `N'  CIGAR  operator;	2) long	insertions are
			 disabled; 3) deletion and  insertion  gap  costs  are
			 different  during chaining; 4)	the computation	of the
			 `ms' tag ignores introns to demote  hits  to  pseudo-
			 genes.

		 splice:hq
			 Long-read splice alignment for	PacBio CCS reads (-xs-
			 plice -C5 -O6,24 -B4).

		 sr	 Short single-end reads	without	 splicing  (-k21  -w11
			 --sr  --frag=yes -A2 -B8 -O12,32 -E2,1	-r50 -p.5 -N20
			 -f1000,5000  -n2  -m20	 -s40  -g200  -2K50m   --heap-
			 sort=yes --secondary=no).

   Miscellaneous options
       --no-kalloc
		 Use  the libc default allocator instead of the	kalloc thread-
		 local allocator.  This	debugging option is mostly  used  with
		 Valgrind  to  detect  invalid	memory accesses. Minimap2 runs
		 slower	with this option, especially  in  the  multi-threading
		 mode.

       --print-qname
		 Print	query  names  to  stderr, mostly to see	which query is
		 crashing minimap2.

       --print-seeds
		 Print seed positions to stderr, for debugging only.

OUTPUT FORMAT
       Minimap2	outputs	mapping	positions in the Pairwise mApping Format (PAF)
       by  default. PAF	is a TAB-delimited text	format with each line consist-
       ing of at least 12 fields as are	described in the following table:

       +----+--------+---------------------------------------------------------+
       |Col |  Type  |			     Description		       |
       +----+--------+---------------------------------------------------------+
       |  1 | string | Query sequence name				       |
       |  2 |  int   | Query sequence length				       |
       |  3 |  int   | Query start coordinate (0-based)			       |
       |  4 |  int   | Query end coordinate (0-based)			       |
       |  5 |  char  | `+' if query/target on the same strand; `-' if opposite |
       |  6 | string | Target sequence name				       |
       |  7 |  int   | Target sequence length				       |
       |  8 |  int   | Target start coordinate on the original strand	       |
       |  9 |  int   | Target end coordinate on	the original strand	       |
       | 10 |  int   | Number of matching bases	in the mapping		       |
       | 11 |  int   | Number bases, including gaps, in	the mapping	       |
       | 12 |  int   | Mapping quality (0-255 with 255 for missing)	       |
       +----+--------+---------------------------------------------------------+

       When alignment is available, column 11 gives the	total  number  of  se-
       quence matches, mismatches and gaps in the alignment; column 10 divided
       by column 11 gives the BLAST-like alignment identity. When alignment is
       unavailable, these two columns are approximate. PAF may optionally have
       additional fields in the	SAM-like typed key-value format. Minimap2  may
       output the following tags:

	+----+------+-------------------------------------------------------+
	|Tag | Type |			   Description			    |
	+----+------+-------------------------------------------------------+
	| tp |	A   | Type of aln: P/primary, S/secondary and I,i/inversion |
	| cm |	i   | Number of	minimizers on the chain			    |
	| s1 |	i   | Chaining score					    |
	| s2 |	i   | Chaining score of	the best secondary chain	    |
	| NM |	i   | Total number of mismatches and gaps in the alignment  |
	| MD |	Z   | To generate the ref sequence in the alignment	    |
	| AS |	i   | DP alignment score				    |
	| ms |	i   | DP score of the max scoring segment in the alignment  |
	| nn |	i   | Number of	ambiguous bases	in the alignment	    |
	| ts |	A   | Transcript strand	(splice	mode only)		    |
	| cg |	Z   | CIGAR string (only in PAF)			    |
	| cs |	Z   | Difference string					    |
	| dv |	f   | Approximate per-base sequence divergence		    |
	| de |	f   | Gap-compressed per-base sequence divergence	    |
	| rl |	i   | Length of	query regions harboring	repetitive seeds    |
	+----+------+-------------------------------------------------------+

       The cs tag encodes difference sequences in the short form or the	entire
       query AND reference sequences in	the long form. It consists of a	series
       of operations:

	 +---+----------------------------+---------------------------------+
	 |Op |		 Regex		  |	      Description	    |
	 +---+----------------------------+---------------------------------+
	 | = | [ACGTN]+			  | Identical sequence (long form)  |
	 | : | [0-9]+			  | Identical sequence length	    |
	 | * | [acgtn][acgtn]		  | Substitution: ref to query	    |
	 | + | [acgtn]+			  | Insertion to the reference	    |
	 | - | [acgtn]+			  | Deletion from the reference	    |
	 | ~ | [acgtn]{2}[0-9]+[acgtn]{2} | Intron length and splice signal |
	 +---+----------------------------+---------------------------------+

LIMITATIONS
       * Minimap2  may produce suboptimal alignments through long low-complex-
	 ity regions where seed	positions may be suboptimal. This  should  not
	 be  a	big concern because even the optimal alignment may be wrong in
	 such regions.

       * Minimap2 requires SSE2	or NEON	instructions to	compile. It is	possi-
	 ble  to  add non-SSE2/NEON support, but it would make minimap2	slower
	 by several times.

SEE ALSO
       miniasm(1), minimap(1), bwa(1).

minimap2-2.17 (r941)		  4 May	2019			   minimap2(1)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OUTPUT FORMAT | LIMITATIONS | SEE ALSO

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=minimap2&sektion=1&manpath=FreeBSD+12.2-RELEASE+and+Ports>

home | help