%\VignetteIndexEntry{An introduction to FilterFFPE}
%\VignetteDepends{}
%\VignetteKeywords{FFPE Artifacts Removal, Structural Variation, NGS}
%\VignettePackage{FilterFFPE}
\documentclass{article}

<<style, echo=FALSE, results=tex>>=
BiocStyle::latex()
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\title{An Introduction to \Biocpkg{FilterFFPE}}
\author{Lanying Wei}
\date{Modified: 20 August, 2020. Compiled: \today}

\begin{document}
\SweaveOpts{concordance=TRUE}

\maketitle

\tableofcontents

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options(width=60)
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\section{Introduction}

The next-generation sequencing (NGS) reads from formalin-fixed paraffin-embedded
(FFPE) samples contain numerous artifact chimeric reads, which can lead to a
large number of false positive structural variation (SV) calls. The
\Biocpkg{FilterFFPE} package finds and filters these artifact chimeric reads
from BAM files of FFPE samples.

\section{Input}

The required input is an indexed BAM file of the FFPE sample, the PCR or optical
duplicates should be marked or removed from the BAM file. Example of such a BAM
file is stored in the 'extdata' directory of \Biocpkg{FilterFFPE} package).

\section{Artifact Chimeric Read Filtration}

The filtration includes two steps: 1) Find artifact chimeric reads from BAM file
. 2) Remove these artifact chimeric reads in the filtered BAM file. We recommend
to also remove PCR or optical duplicates of all chimeric reads, since these
reads may contain duplicates of artifact chimeric reads.
\Rfunction{findArtifactChimericReads} can be used to find artifact chimeric
reads, read names of PCR or optical duplicates of all chimeric reads are also
found and written in a txt file by this function.
\Rfunction{filterBamByReadNames} can be used for further filtration, it
generates a filtered and indexed BAM file. \Rfunction{FFPEReadFilter} combines
these two functions.

<<findArtifactChimericReads>>=
library(FilterFFPE)

# Find artifact chimeric reads
file <- system.file("extdata", "example.bam", package = "FilterFFPE")
outFolder <- tempdir()
FFPEReadsFile <- paste0(outFolder, "/example.FFPEReads.txt")
dupChimFile <- paste0(outFolder, "/example.dupChim.txt")
artifactReads <- findArtifactChimericReads(file = file, threads = 2,
                                           FFPEReadsFile = FFPEReadsFile,
                                           dupChimFile = dupChimFile)
head(artifactReads)

@
%%

<<filterBamByReadNames>>=
# Filter artifact chimeric reads and PCR or optical duplicates of chimeric reads
dupChim <- readLines(dupChimFile)
readsToFilter <- c(artifactReads, dupChim)
destination <- paste0(outFolder, "/example.FilterFFPE.bam")
filterBamByReadNames(file = file, readsToFilter = readsToFilter,
                     destination = destination, overwrite=TRUE)

@
%%

<<FFPEReadFilter>>=
# Perform finding and filtering with one function
file <- system.file("extdata", "example.bam", package = "FilterFFPE")
outFolder <- tempdir()
FFPEReadsFile <- paste0(outFolder, "/example.FFPEReads.txt")
dupChimFile <- paste0(outFolder, "/example.dupChim.txt")
destination <- paste0(outFolder, "/example.FilterFFPE.bam")
FFPEReadFilter(file = file, threads=2, destination = destination,
               overwrite=TRUE, FFPEReadsFile = FFPEReadsFile,
               dupChimFile = dupChimFile)

@
%%

The generated BAM file can be loaded with \Rfunction{scanBam} function from \Biocpkg{Rsamtools} package for further interrogation.

<<scanBAM>>=
# load Bam file with scanBAM
newBam <- Rsamtools::scanBam(destination)
head(newBam[[1]]$seq)
@

\appendix
\section{Session info}
<<sessionInfo>>=
packageDescription("FilterFFPE")
sessionInfo()
@

%%

\end{document}