def rename_cols(df,names,renames=None,prefix=None,suffix=None):
    """
    rename columns of a pandas table

    :param df: pandas dataframe
    :param names: list of new column names
    """
    if not prefix is None:
        renames=[ "%s%s" % (prefix,s) for s in names]
    if not suffix is None:    
        renames=[ "%s%s" % (s,suffix) for s in names]
    if not renames is None:
        for i,name in enumerate(names):
#             names=[renames[i] if s==names[i] else s for s in names]    
            rename=renames[i]    
            df.loc[:,rename]=df.loc[:,name]
        df=df.drop(names,axis=1)
        return df