python之将输入代码拆分为 3 个字母并使用 if 语句返回 DNA->氨基酸字母

它正在按预期读取前 3 个字母，但我如何让它读取接下来的 3 个字母作为不同的字符串，以便它可以再次运行 if、elif、else 语句。

else X 在那里是因为它不需要我做其余的。

该表之所以存在，只是因为它有助于查看它是否返回了正确的字母。

dna = input("Enter the DNA sequence to translate: ") 
 
if dna == "ATA" or dna == "ATC" or dna == "ATT": 
  print ("I") 
elif dna == "CTA" or dna == "CTC" or dna == "CTG" or dna == "CTT" or dna == "TAA" or dna =="TTG": 
  print ("L") 
elif dna == "GTA" or dna == "GTC" or dna == "GTG" or dna == "GTT": 
  print ("V") 
elif dna == "TTC" or dna == "TTT": 
  print ("F") 
elif dna == "ATG": 
  print ("M") 
else: 
  print ("X") 
 
 
CodonDict = { 
'ATT':'I',   'ATC':'I',  'ATA':'I',  'CTT':'L',  'CTC':'L',   
'CTA':'L',  'CTG':'L',  'TTA':'L',  'TTG':'L',  'GTT':'V',  'GTC':'V',   
'GTA':'V',  'GTG':'V',  'TTT':'F',  'TTC':'F',  'ATG':'M',  'TGT':'C',   
'TGC':'C',  'GCT':'A',  'GCC':'A',  'GCA':'A',  'GCG':'A',  'GGT':'G',   
'GGC':'G',  'GGA':'G',  'GGG':'G',  'CCT':'P',  'CCC':'P',  'CCA':'P',   
'CCG':'P',  'ACT':'T',  'ACC':'T',  'ACA':'T',  'ACG':'T',  'TCT':'S',   
'TCC':'S',  'TCA':'S',  'TCG':'S',  'AGT':'S',  'AGC':'S',  'TAT':'Y',   
'TAC':'Y',  'TGG':'W',  'CAA':'Q',  'CAG':'Q',  'AAT':'N',  'AAC':'N',   
'CAT':'H',  'CAC':'H',  'GAA':'E',  'GAG':'E',  'GAT':'D',  'GAC':'D',   
'AAA':'K',  'AAG':'K',  'CGT':'R',  'CGC':'R',  'CGA':'R',  'CGG':'R',   
'AGA':'R',  'AGG':'R',  'TAA':'X',  'TAG':'X',  'TGA':'X'}  
 
For example I input: ATT 
Returns I as expected. 
 
I input: ATTATT 
Returns X as expected but how do I treat the 3 letters as separate. 
It should return II. 

请您参考如下方法:

例子:

input = 'ATTATTTTAGGG' 
for i in range(0,len(intput),3): 
    print (input[i:i+3])  

输出:

ATT 
ATT 
TTA 
GGG 

Accessing Values in Strings Python does not support a character type; these are treated as strings of length one, thus also considered a substring.

To access substrings, use the square brackets for slicing along with the index or indices to obtain your substring. For example −

var1 = 'Hello World!'   
var2 = "Python Programming" 
 
print ("var1[0]: ", var1[0])   
print ("var2[1:5]: ", var2[1:5]) 

output:

var1[0]:  H   
var2[1:5]:  ytho 

方案一:

dna_ = input("Enter the DNA sequence to translate: ") 
for i in range(0,len(dna_),3): 
    #print (dna_[i:i+3]) 
    dna = dna_[i:i+3] 
    if dna == "ATA" or dna == "ATC" or dna == "ATT": 
      print ("I") 
    elif dna == "CTA" or dna == "CTC" or dna == "CTG" or dna == "CTT" or dna == "TAA" or dna =="TTG": 
      print ("L") 
    elif dna == "GTA" or dna == "GTC" or dna == "GTG" or dna == "GTT": 
      print ("V") 
    elif dna == "TTC" or dna == "TTT": 
      print ("F") 
    elif dna == "ATG": 
      print ("M") 
    else: 
      print ("X") 

解决方案2:(如果你想使用现有的字典)

dna_ = input("Enter the DNA sequence to translate: ") 
for i in range(0,len(dna_),3): 
    #print (dna_[i:i+3]) 
    dna = dna_[i:i+3] 
    for key, val in CodonDict.items(): 
        if key == dna: 
            print (val) 

输出:

Enter the DNA sequence to translate: TGCCTG 
C 
L