def summary_table(params, proteins):
    """
    Returns a string representing a simple summary table of
    protein classifcations.
    """
    out = ""
    counts = {}
    for seqid in proteins:
        category = proteins[seqid]['category']

        if category not in counts:
            counts[category] = 1
        else:
            counts[category] += 1

    out += "\n\n# Number of proteins in each class:\n"
    pse_total = 0

    for c in counts:
        if "PSE-" in c:
            pse_total += counts[c]
    counts["PSE(total)"] = pse_total

    for c in sorted(counts):
        if "PSE-" in c:
            spacer = "  "
            pse_total += counts[c]
        else:
            spacer = ""
        out += "# %s%-15s\t%i\n" % (spacer, c, counts[c])

    # out += "#\n# PSE(total)\t\t%i\n" % (pse_total)

    return out