crossSetSimDisk: Parallel Protein Sequence Similarity Calculation Between Two...

In protr: Generating Various Numerical Representation Schemes for Protein Sequences

Parallel Protein Sequence Similarity Calculation Between Two Sets Based on Sequence Alignment (Disk-Based Version)

Description

Parallel calculation of protein sequence similarity based on sequence alignment between two sets of protein sequences. This version offloads the partial results in each batch to the hard drive and merges the results together in the end, which reduces the memory usage.

Usage

crossSetSimDisk(
  protlist1,
  protlist2,
  cores = 2,
  batches = 1,
  path = tempdir(),
  verbose = FALSE,
  type = "local",
  submat = "BLOSUM62",
  gap.opening = 10,
  gap.extension = 4
)

Arguments

protlist1	A length n list containing n protein sequences, each component of the list is a character string, storing one protein sequence. Unknown sequences should be represented as "".
protlist2	A length n list containing m protein sequences, each component of the list is a character string, storing one protein sequence. Unknown sequences should be represented as "".
cores	Integer. The number of CPU cores to use for parallel execution, default is 2. Users can use the availableCores() function in the parallelly package to see how many cores they could use.
batches	Integer. How many batches should we split the pairwise similarity computations into. This is useful when you have a large number of protein sequences, enough number of CPU cores, but not enough RAM to compute and fit all the pairwise similarities into a single batch. Defaults to 1.
path	Directory for caching the results in each batch. Defaults to the temporary directory.
verbose	Print the computation progress? Useful when batches > 1.
type	Type of alignment, default is "local", can be "global" or "local", where "global" represents Needleman-Wunsch global alignment; "local" represents Smith-Waterman local alignment.
submat	Substitution matrix, default is "BLOSUM62", can be one of "BLOSUM45", "BLOSUM50", "BLOSUM62", "BLOSUM80", "BLOSUM100", "PAM30", "PAM40", "PAM70", "PAM120", or "PAM250".
gap.opening	The cost required to open a gap of any length in the alignment. Defaults to 10.
gap.extension	The cost to extend the length of an existing gap by 1. Defaults to 4.

Value

A n x m similarity matrix.

Author(s)

Nan Xiao <https://nanx.me>

See Also

See crossSetSim for the in-memory version.

Examples

## Not run: 

# Be careful when testing this since it involves parallelization
# and might produce unpredictable results in some environments

library("Biostrings")
library("foreach")
library("doParallel")

s1 <- readFASTA(system.file("protseq/P00750.fasta", package = "protr"))[[1]]
s2 <- readFASTA(system.file("protseq/P08218.fasta", package = "protr"))[[1]]
s3 <- readFASTA(system.file("protseq/P10323.fasta", package = "protr"))[[1]]
s4 <- readFASTA(system.file("protseq/P20160.fasta", package = "protr"))[[1]]
s5 <- readFASTA(system.file("protseq/Q9NZP8.fasta", package = "protr"))[[1]]

set.seed(1010)
plist1 <- as.list(c(s1, s2, s3, s4, s5)[sample(1:5, 100, replace = TRUE)])
plist2 <- as.list(c(s1, s2, s3, s4, s5)[sample(1:5, 100, replace = TRUE)])
psimmat <- crossSetSimDisk(
  plist1, plist2,
  cores = 2, batches = 10, verbose = TRUE,
  type = "local", submat = "BLOSUM62"
)

## End(Not run)

protr documentation built on Sept. 12, 2024, 6:44 a.m.