DataFrame statistics columns in a character occurrences and compare

pd.DataFrame c = ({ 'id': [ 'xx', 'xyy', 'zz', 'mm], the [' 10 ', 10', 11 ', np.nan] , 'b': [ '11', 12 ', 11', np.nan] c: [ '10', '12', '', np.nan] d: [ ' 10 ', 10', 10 ', np.nan], he [' 10 ',' 10 ',' 11 ',' ']}) 
c

　　

def map_func1(x):
    if (x['a'] == x['b'] == x['c'] == x['d'] == ''):
        return 'www'
    else:
        li = list(x[['a','b','c','d']])
        print(li)
        set1 = set(li)
        dict1 = {}
        for item in set1:
            dict1.update({item:li.count(item)})
        print(dict1)
        return max(dict1,key=dict1.get)

　　

aa [ 'xinlai'] = aa.apply (map_func1, axis = 1) #axis controlled by row or by column