如何測試for循環中的單個字符與另一個字符串的整個字符串？

Question

rna = input('Enter a rna sequence: ') 
for i in rna: 
    if i in 'acguACGU': 
     print('That is a valid rna sequence.') 
    else: 
     print('That is not a valid rna sequence.') 

我想讓用戶輸入對字符串進行測試，並且只在用戶輸入中的每個字母有效或無效時纔打印答案。 （EX：GCC的輸入應該給我的一個打印（「這是一個有效的RNA序列」），而不是打印3次

Answer 1

rna = input('Enter a rna sequence: ') 
if all(c in "acgu" for c in rna.lower()): 
    print('That is a valid rna sequence.') 
else: 
    print('That is not a valid rna sequence.') 

Answer 2

您可以使用set和測試，如果設定的rna（用戶。輸入）是你的包含所有可能的字符（或其他方式圓，集合的子集，如果集的所有可能的字符是一個超集的組輸入）的例子 -

rna = input('Enter a rna sequence: ') 
seq = set('acguACGU') 
if seq.issuperset(rna): 
    print('That is a valid rna sequence.') 
else: 
    print('That is not a valid rna sequence.') 

Answer 3

rna = input('Enter a rna sequence: ') 
for i in rna: 
    if i not in 'acguACGU': 
     print('That is not a valid rna sequence.') 
     break 
else: 
    print('That is a valid rna sequence.') 

見 - https://docs.python.org/2/tutorial/controlflow.html#break-and-continue-statements-and-else-clauses-on-loops