generand:生成FASTAFASTQ，SAM或VCF格式的随机基因组数据

# generand Generate random genomic data in FASTA/FASTQ, SAM, or VCF format, output to the standard output. Output data is completely random and suitable for basic testing and benchmarking of new programs, or for quickly generating small samples for academic purposes. Generand is especially useful for generating large test inputs on-the-fly so that they need not be manually generated and/or stored. Currently the randomization is very simplistic, but we will likely add paramaters in the future to allow generating more realistic data for specific situations. # Usage generand fasta sequences sequence-length generand fastq sequences sequence-length generand sam chromosomes alignments-per-chromosome sequence-length generand vcf chromosomes calls-per-chromosome samples # Description generand fast[aq] sequences sequence-length generates a FASTA or FASTQ stream of "sequences" sequences, each of length "sequence-length". The sequence content is random with a uniform distribution of bases, so that GC content should be very close to 50%. PHRED scores in FASTQ streams are generated in blocks of equal scores and are mostly high-quality. The last few scores are lower quality and independent to simulate Illumina sequencing, where quality tends to drop near the end of each read. generand sam chromosomes alignments-per-chromosome sequence-length generates a SAM stream with chromosomes * alignments-per-chromosome total alignments. It outputs increasing indexes for QNAME and CHROM, randomly increasing POS, random QUAL scores, and random sequences and PHRED scores as stated for FASTQ above. generand vcf chromosomes calls-per-chromosome samples generates a VCF stream with chromosomes * calls-per-chromosome calls. It outputs chromosomes with increasing indexes, randomly increasing POS, uniformly random REF and ALT, uniformly random QUAL scores, and random sample columns including GT (genotype), AD (allelic depth) and DP (depth). REF counts are always >= ALT counts in the AD data and DP = REF count + ALT count.