def read_in_id_val_cols(in_file,
                        id_col=3,
                        val_col=4,
                        val_type=1):
    """
    Read in ID value combination into dic. id_col + val_col 0-based.

    val_type:
        1 : float
        2 : integer

    """
    id2val_dic = {}

    with open(in_file) as f:
        for line in f:
            cols = line.strip().split("\t")
            id_str = cols[id_col]
            val = cols[val_col]
            if val_type == 1:
                val = float(val)
            elif val_type == 2:
                val = int(val)
            assert id_str not in id2val_dic, "ID %s (col: %i) appears > 1 in file %s" %(id_str, id_col, in_file)
            id2val_dic[id_str] = val
    f.closed
    assert id2val_dic, "id2val_dic empty (nothing read in)"
    return id2val_dic