after quantitation, combine the counts/FPKM/TPM/etc into a single table with
    all samples

def combine_files(samples):
    """
    after quantitation, combine the counts/FPKM/TPM/etc into a single table with
    all samples
    """
    data = samples[0][0]
    # prefer the supplied transcriptome gtf file
    gtf_file = dd.get_transcriptome_gtf(data, None)
    if not gtf_file:
        gtf_file = dd.get_gtf_file(data, None)
    dexseq_gff = dd.get_dexseq_gff(data)

    # combine featureCount files
    count_files = filter_missing([dd.get_count_file(x[0]) for x in samples])
    combined = count.combine_count_files(count_files, ext=".counts")
    annotated = count.annotate_combined_count_file(combined, gtf_file)

    # add tx2gene file
    tx2gene_file = os.path.join(dd.get_work_dir(data), "annotation", "tx2gene.csv")
    if gtf_file:
        tx2gene_file = sailfish.create_combined_tx2gene(data)

    # combine eXpress files
    express_counts_combined = combine_express(samples, combined)

    # combine Cufflinks files
    fpkm_files = filter_missing([dd.get_fpkm(x[0]) for x in samples])
    if fpkm_files and combined:
        fpkm_combined_file = os.path.splitext(combined)[0] + ".fpkm"
        fpkm_combined = count.combine_count_files(fpkm_files, fpkm_combined_file)
    else:
        fpkm_combined = None
    isoform_files = filter_missing([dd.get_fpkm_isoform(x[0]) for x in samples])
    if isoform_files and combined:
        fpkm_isoform_combined_file = os.path.splitext(combined)[0] + ".isoform.fpkm"
        fpkm_isoform_combined = count.combine_count_files(isoform_files,
                                                          fpkm_isoform_combined_file,
                                                          ".isoform.fpkm")
    else:
        fpkm_isoform_combined = None
    # combine DEXseq files
    to_combine_dexseq = filter_missing([dd.get_dexseq_counts(data[0]) for data
                                        in samples])
    if to_combine_dexseq and combined:
        dexseq_combined_file = os.path.splitext(combined)[0] + ".dexseq"
        dexseq_combined = count.combine_count_files(to_combine_dexseq,
                                                    dexseq_combined_file, ".dexseq")
        if dexseq_combined:
            dexseq.create_dexseq_annotation(dexseq_gff, dexseq_combined)
    else:
        dexseq_combined = None
    samples = spikein.combine_spikein(samples)
    updated_samples = []
    for data in dd.sample_data_iterator(samples):
        if combined:
            data = dd.set_combined_counts(data, combined)
        if annotated:
            data = dd.set_annotated_combined_counts(data, annotated)
        if fpkm_combined:
            data = dd.set_combined_fpkm(data, fpkm_combined)
        if fpkm_isoform_combined:
            data = dd.set_combined_fpkm_isoform(data, fpkm_isoform_combined)
        if express_counts_combined:
            data = dd.set_express_counts(data, express_counts_combined['counts'])
            data = dd.set_express_tpm(data, express_counts_combined['tpm'])
            data = dd.set_express_fpkm(data, express_counts_combined['fpkm'])
            data = dd.set_isoform_to_gene(data, express_counts_combined['isoform_to_gene'])
        if dexseq_combined:
            data = dd.set_dexseq_counts(data, dexseq_combined_file)
        if gtf_file:
            data = dd.set_tx2gene(data, tx2gene_file)
        updated_samples.append([data])
    return updated_samples