fastp 下载及安装
#安装方式一: 下载编译好二进制(仅适用于linux系统)
chmod a+x ./fastp
#安装方式二: 源码编译
git clone https://github.com/OpenGene/fastp.git
cd fastp
make
sudo make install
fastp输入输出
单端数据:read1通过-i或--in1输入,-o或者--out1特异性输出
双端数据:read2通过-I或--in2输入,-O或者--out2特异性输出
如果文件名是.gz,默认输出是gzip压缩文件
质量过滤
# 质量过滤
默认会进行低质过滤,如果不希望进行,可使用参数-Q或者“disable_quality_filtering”目前支持过滤通过N碱基的数量和不合格碱基的百分比。
-q,--disable_quality_filtering 设置碱基的质量值。默认平均质量值>=Q15是合格的
-u,--unqualified_percent_limit 允许多少百分比的碱基不合格(0~100)。默认40%
或者通过平均质量值过滤数据
-e, --average_qual 如果一条reads的平均质量值小于平均质量值,即将这条reads或paire reads丢弃。默认0
# 长度过滤
默认进行长度过滤,可以通过参数-L或--disable_length_filtering禁用。最小长度要求可以用-l或--length_required指定
# 低复杂过滤
默认不进行低复杂过滤,可以通过参数-y或--low_complexity_filter进行低复杂序列过滤(ase[i] != base[i+1])。
低复杂序列阈值可以使用参数-Y或者--complexity_threshold进行指定,阈值的范围需在0~100之间,默认是30
接头过滤
默认进行接头过滤,但可以使用参数-A或者--disable_adapter_trimming禁用,接头序列可自动地在PE/SE数据中发现。
SE数据,通过分析前1Mreads来评估接头,该评估方式不精确。可以通过参数-a或者--adapter_sequence 指定adapter序列。如果接头序列是指定的,自动检测接头序列被禁止。
PE数据,接头序列发现通过overlap分析,该方法粗暴快速,通常不需要输入接头序列,但是也可以通过参数--adapter_sequence指定read1中的接头序列,参数--adapter_sequence_r2指定read2上的接头序列。如果fastp寻找overlap失败(低复杂序列等等原因),则会使用指定的序列去trim接头。
PE数据,接头序列自动查找默认是禁用的,自接头可以通过overlap分析被trimmed,然而,也可以指定--detect_adapter_for_pe去调用
PE数据,如果指定接头序列或者自动检测接头序列fastp运行速度较慢,但输出的结果会更加干净,可能由于测序错误或者接头二聚体导致overlap分析失败
广泛使用的接头序列是Illumina Truseq接头,可将(--adapter_sequence=AGATCGGAAGAGCACACGTCTGAACTCCAGTCA和--adapter_sequence_r2=AGATCGGAAGAGCGTCGTGTAGGGAAAGAGTGT)加入到命令行或者通过指定detect_adapter_for_pe自动发现
fastp包含一些内置已知的接头序列用于更好的发现序列中的接头
具体参数见 fastp -h
usage: ./fastp [options] ...
options:
-i, --in1 read1 input file name (string [=])
-o, --out1 read1 output file name (string [=])
-I, --in2 read2 input file name (string [=])
-O, --out2 read2 output file name (string [=])
--unpaired1 for PE input, if read1 passed QC but read2 not, it will be written to unpaired1. Default is to discard it. (string [=])
--unpaired2 for PE input, if read2 passed QC but read1 not, it will be written to unpaired2. If --unpaired2 is same as --umpaired1 (default mode), both unpaired reads will be written to this same file. (string [=])
--failed_out specify the file to store reads that cannot pass the filters. (string [=])
-m, --merge for paired-end input, merge each pair of reads into a single read if they are overlapped. The merged reads will be written to the file given by --merged_out, the unmerged reads will be written to the files specified by --out1 and --out2. The merging mode is disabled by default.
--merged_out in the merging mode, specify the file name to store merged output, or specify --stdout to stream the merged output (string [=])
--include_unmerged in the merging mode, write the unmerged or unpaired reads to the file specified by --merge. Disabled by default.
-6, --phred64 indicate the input is using phred64 scoring (it'll be converted to phred33, so the output will still be phred33)
-z, --compression compression level for gzip output (1 ~ 9). 1 is fastest, 9 is smallest, default is 4. (int [=4])
--stdin input from STDIN. If the STDIN is interleaved paired-end FASTQ, please also add --interleaved_in.
--stdout stream passing-filters reads to STDOUT. This option will result in interleaved FASTQ output for paired-end output. Disabled by default.
--interleaved_in indicate that <in1> is an interleaved FASTQ which contains both read1 and read2. Disabled by default.
--reads_to_process specify how many reads/pairs to be processed. Default 0 means process all reads. (int [=0])
--dont_overwrite don't overwrite existing files. Overwritting is allowed by default.
-V, --verbose output verbose log information (i.e. when every 1M reads are processed).
-A, --disable_adapter_trimming adapter trimming is enabled by default. If this option is specified, adapter trimming is disabled
-a, --adapter_sequence the adapter for read1. For SE data, if not specified, the adapter will be auto-detected. For PE data, this is used if R1/R2 are found not overlapped. (string [=auto])
--adapter_sequence_r2 the adapter for read2 (PE data only). This is used if R1/R2 are found not overlapped. If not specified, it will be the same as <adapter_sequence> (string [=auto])
--adapter_fasta specify a FASTA file to trim both read1 and read2 (if PE) by all the sequences in this FASTA file (string [=])
--detect_adapter_for_pe by default, the auto-detection for adapter is for SE data input only, turn on this option to enable it for PE data.
-f, --trim_front1 trimming how many bases in front for read1, default is 0 (int [=0])
-t, --trim_tail1 trimming how many bases in tail for read1, default is 0 (int [=0])
-b, --max_len1 if read1 is longer than max_len1, then trim read1 at its tail to make it as long as max_len1. Default 0 means no limitation (int [=0])
-F, --trim_front2 trimming how many bases in front for read2. If it's not specified, it will follow read1's settings (int [=0])
-T, --trim_tail2 trimming how many bases in tail for read2. If it's not specified, it will follow read1's settings (int [=0])
-B, --max_len2 if read2 is longer than max_len2, then trim read2 at its tail to make it as long as max_len2. Default 0 means no limitation. If it's not specified, it will follow read1's settings (int [=0])
-g, --trim_poly_g force polyG tail trimming, by default trimming is automatically enabled for Illumina NextSeq/NovaSeq data
--poly_g_min_len the minimum length to detect polyG in the read tail. 10 by default. (int [=10])
-G, --disable_trim_poly_g disable polyG tail trimming, by default trimming is automatically enabled for Illumina NextSeq/NovaSeq data
-x, --trim_poly_x enable polyX trimming in 3' ends.
--poly_x_min_len the minimum length to detect polyX in the read tail. 10 by default. (int [=10])
-5, --cut_front move a sliding window from front (5') to tail, drop the bases in the window if its mean quality < threshold, stop otherwise.
-3, --cut_tail move a sliding window from tail (3') to front, drop the bases in the window if its mean quality < threshold, stop otherwise.
-r, --cut_right move a sliding window from front to tail, if meet one window with mean quality < threshold, drop the bases in the window and the right part, and then stop.
-W, --cut_window_size the window size option shared by cut_front, cut_tail or cut_sliding. Range: 1~1000, default: 4 (int [=4])
-M, --cut_mean_quality the mean quality requirement option shared by cut_front, cut_tail or cut_sliding. Range: 1~36 default: 20 (Q20) (int [=20])
--cut_front_window_size the window size option of cut_front, default to cut_window_size if not specified (int [=4])
--cut_front_mean_quality the mean quality requirement option for cut_front, default to cut_mean_quality if not specified (int [=20])
--cut_tail_window_size the window size option of cut_tail, default to cut_window_size if not specified (int [=4])
--cut_tail_mean_quality the mean quality requirement option for cut_tail, default to cut_mean_quality if not specified (int [=20])
--cut_right_window_size the window size option of cut_right, default to cut_window_size if not specified (int [=4])
--cut_right_mean_quality the mean quality requirement option for cut_right, default to cut_mean_quality if not specified (int [=20])
-Q, --disable_quality_filtering quality filtering is enabled by default. If this option is specified, quality filtering is disabled
-q, --qualified_quality_phred the quality value that a base is qualified. Default 15 means phred quality >=Q15 is qualified. (int [=15])
-u, --unqualified_percent_limit how many percents of bases are allowed to be unqualified (0~100). Default 40 means 40% (int [=40])
-n, --n_base_limit if one read's number of N base is >n_base_limit, then this read/pair is discarded. Default is 5 (int [=5])
-e, --average_qual if one read's average quality score <avg_qual, then this read/pair is discarded. Default 0 means no requirement (int [=0])
-L, --disable_length_filtering length filtering is enabled by default. If this option is specified, length filtering is disabled
-l, --length_required reads shorter than length_required will be discarded, default is 15. (int [=15])
--length_limit reads longer than length_limit will be discarded, default 0 means no limitation. (int [=0])
-y, --low_complexity_filter enable low complexity filter. The complexity is defined as the percentage of base that is different from its next base (base[i] != base[i+1]).
-Y, --complexity_threshold the threshold for low complexity filter (0~100). Default is 30, which means 30% complexity is required. (int [=30])
--filter_by_index1 specify a file contains a list of barcodes of index1 to be filtered out, one barcode per line (string [=])
--filter_by_index2 specify a file contains a list of barcodes of index2 to be filtered out, one barcode per line (string [=])
--filter_by_index_threshold the allowed difference of index barcode for index filtering, default 0 means completely identical. (int [=0])
-c, --correction enable base correction in overlapped regions (only for PE data), default is disabled
--overlap_len_require the minimum length to detect overlapped region of PE reads. This will affect overlap analysis based PE merge, adapter trimming and correction. 30 by default. (int [=30])
--overlap_diff_limit the maximum number of mismatched bases to detect overlapped region of PE reads. This will affect overlap analysis based PE merge, adapter trimming and correction. 5 by default. (int [=5])
--overlap_diff_percent_limit the maximum percentage of mismatched bases to detect overlapped region of PE reads. This will affect overlap analysis based PE merge, adapter trimming and correction. Default 20 means 20%. (int [=20])
-U, --umi enable unique molecular identifier (UMI) preprocessing
--umi_loc specify the location of UMI, can be (index1/index2/read1/read2/per_index/per_read, default is none (string [=])
--umi_len if the UMI is in read1/read2, its length should be provided (int [=0])
--umi_prefix if specified, an underline will be used to connect prefix and UMI (i.e. prefix=UMI, UMI=AATTCG, final=UMI_AATTCG). No prefix by default (string [=])
--umi_skip if the UMI is in read1/read2, fastp can skip several bases following UMI, default is 0 (int [=0])
-p, --overrepresentation_analysis enable overrepresented sequence analysis.
-P, --overrepresentation_sampling one in (--overrepresentation_sampling) reads will be computed for overrepresentation analysis (1~10000), smaller is slower, default is 20. (int [=20])
-j, --json the json format report file name (string [=fastp.json])
-h, --html the html format report file name (string [=fastp.html])
-R, --report_title should be quoted with ' or ", default is "fastp report" (string [=fastp report])
-w, --thread worker thread number, default is 2 (int [=2])
-s, --split split output by limiting total split file number with this option (2~999), a sequential number prefix will be added to output name ( 0001.out.fq, 0002.out.fq...), disabled by default (int [=0])
-S, --split_by_lines split output by limiting lines of each file with this option(>=1000), a sequential number prefix will be added to output name ( 0001.out.fq, 0002.out.fq...), disabled by default (long [=0])
-d, --split_prefix_digits the digits for the sequential number padding (1~10), default is 4, so the filename will be padded as 0001.xxx, 0 to disable padding (int [=4])
--cut_by_quality5 DEPRECATED, use --cut_front instead.
--cut_by_quality3 DEPRECATED, use --cut_tail instead.
--cut_by_quality_aggressive DEPRECATED, use --cut_right instead.
--discard_unmerged DEPRECATED, no effect now, see the introduction for merging.
-?, --help print this message