Package 'SeqAlignR'

Sequence Alignment

Description

Performs sequence alignment on two sequences by a user specified alignment method. As of now, only the Needleman-Wunsch algorithm is supported.

Usage

align_sequences(seq1, seq2, d, mismatch, match, method = "needleman")

Arguments

seq1	First sequence to align.
seq2	Second sequence to align.
d	Gap penalty, should be negative.
mismatch	Mismatch penalty, should be negative.
match	Match score, should be positive.
method	Name of alignment algorithm. Currently only supports "needleman".

Value

Object of class alignment representing the alignment result. This object can be utilized with the plot.alignment function to visualize the alignment matrix and the print.alignment function to display alignments in the console.

References

For more details on the Needleman-Wunsch algorithm, see the wikipedia page.

Examples

seq1 <- "GCATGCG"
seq2 <- "GATTACA"
# Run the Needleman-Wunsch algorithm
align_sequences(seq1, seq2, d = -1, mismatch = -1, match = 1)

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Plot Alignment Matrix

Description

Produces a plot displaying the alignment matrix of seq1 and seq2.

Usage

## S3 method for class 'alignment'
plot(x, ...)

Arguments

x	Object of class alignment (see align_sequences).
...	Additional parameters to be passed to the plot() function.

Details

The first sequence (seq1) is represented by the columns and the second sequence (seq2) is represented by the rows. The first column and first row are left bank, meaning a gap. Each cell in the matrix displays the score. The subtitle states the match, mismatch and gap penalty d used in the algorithm. A mismatch is shown by the red arrows, a match by the blue arrows, and a gap by the green arrows. The alignment(s) with the highest score are highlighted with thick gray borders.

Value

Plot of the alignment matrix.

References

The implementation is inspired by the visualization (code) by Kamil Slowikowski (ORCID).

Examples

seq1 <- "GCATGCG"
seq2 <- "GATTACA"
# Run the Needleman-Wunsch algorithm
alignment1 <- align_sequences(seq1, seq2, d = -1, mismatch = -1, match = 1)
# Plot the matrix
plot(alignment1)

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Print Alignments

Description

Prints the alignments between seq1 and seq2 with the highest score.

Usage

## S3 method for class 'alignment'
print(x, ...)

Arguments

x	Object of class alignment (see align_sequences).
...	Additional parameters to be passed to the cat() function, displaying the alignment.

Details

The printed message includes the alignment score. This function may display multiple alignments, as alignments with the same score are possible.

Value

Console print of alignments.

Examples

seq1 <- "GCATGCG"
seq2 <- "GATTACA"
# Run the Needleman-Wunsch algorithm
alignment1 <- align_sequences(seq1, seq2, d = -1, mismatch = -1, match = 1)
# Print the alignments
print(alignment1)

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Sequence Alignment Tool

Description

Sequence alignment and visualization tool designed to enhance understanding of sequence alignment algorithms, such as the Needleman-Wunsch algorithm. Through detailed matrix plot visualizations with arrows illustrating the path of different alignments, users can gain insights into how these algorithms score and identify optimal alignments between two sequences.

Getting started

1. Install the SeqAlignR package from CRAN using:

   install.packages("SeqAlignR")

2. Load the SeqAlignR package into your R session:

   library(SeqAlignR)

3. Explore the documentation for align_sequences or see the example below:

   ?align_sequences

Author(s)

Leonard Persson Norblad [email protected] (ORCID)

References

The graphics in the package were inspired by this code by Kamil Slowikowski (ORCID).

Examples

seq1 <- "GCATGCG"
seq2 <- "GATTACA"
# Run the Needleman-Wunsch algorithm
alignment1 <- align_sequences(seq1, seq2, d = -1, mismatch = -1, match = 1, method="needleman")
# Print the alignments
print(alignment1)
# Plot the matrix
plot(alignment1)

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