def get_vars(varstr):
    """Gets 2d variable labels from a single string"""
    variables = ['x', 'y', 'z', 'px', 'py', 'pz', 't']

    #all_2d_vars = {}
    for var1 in variables:
        for var2 in variables:
            if(varstr == f'{var1}{var2}'):
                return [var1,var2]