def strain_sort(data_dict):
    """
    Sorts a dictionary by strain

    The input dictionary should consist of plasmid keys and data for values
    The sorted dictionary with have strains for the keys and plasmid/data
    dictionaries as the values.
    """
    strain_dict = {}
    for plasmid, data in data_dict.items():
        strain = plasmid.split('_')[0]
        if strain not in strain_dict.keys():
            strain_dict[strain] = {}
        strain_dict[strain][plasmid] = data
    return strain_dict
