英文:
How to conditionally build a list in a for loop in python
问题
sequence_C = []
for i in sequence:
if i == "A":
sequence_C.append("T")
elif i == "T":
sequence_C.append("A")
elif i == "C":
sequence_C.append("G")
else:
sequence_C.append("C")
print(sequence_C)
英文:
How could I make sequence_C with the values after the if print as one list like sequence
sequence=["A","C","G","T","T","A","G","C","T","A","A","C","G"]
for i in sequence:
sequence_C=[]
if i=="A":
sequence_C.append("T")
elif i=="T":
sequence_C.append("A")
elif i=="C":
sequence_C.append("G")
else:
sequence_C.append("C")
print(sequence_C)
答案1
得分: 1
只初始化sequence_C一次，在循环开始之前。
sequence_C = []
for i in sequence:
if i == "A":
sequence_C.append("T")
elif i == "T":
sequence_C.append("A")
elif i == "C":
sequence_C.append("G")
else:
sequence_C.append("C")
print(sequence_C)
你可以更容易地使用字典和列表推导来解决这个问题，就像这样：
mapping = {'T': 'A', 'A': 'T', 'G': 'C', 'C': 'G'}
sequence_C = [mapping[item] for item in sequence]
这样做的好处是减少了重复的代码。
英文:
Only initialise sequence_C once, before the loop starts.
sequence_C = []
for i in sequence:
if i=="A":
sequence_C.append("T")
elif i=="T":
sequence_C.append("A")
elif i=="C":
sequence_C.append("G")
else:
sequence_C.append("C")
print(sequence_C)
You can more easily solve this using a dictionary and a list comprehension, like so:
mapping = {'T': 'A', 'A': 'T', 'G': 'C', 'C': 'G'}
sequence_C = [mapping[item] for item in sequence]
There's a lot less duplicated code like this!
答案2
得分: 1
代码部分不翻译：
The only thing that should happen to sequence_C inside the loop is to have values appended to it. Do not initialize it to [] in the loop, and do not print the value of sequence_C in the loop.
翻译：
循环内唯一应该发生的事情是将值附加到sequence_C。不要在循环中初始化它为[]，也不要在循环中打印sequence_C的值。
The simplest thing to do, though, is to create a translation table.
翻译：
不过，最简单的方法是创建一个翻译表。
英文:
The only thing that should happen to sequence_C inside the loop is to have values appended to it. Do not initialize it to [] in the loop, and do not print the value of sequence_C in the loop.
sequence=["A","C","G","T","T","A","G","C","T","A","A","C","G"]
sequence_C = []
for i in sequence:
if i=="A":
sequence_C.append("T")
elif i=="T":
sequence_C.append("A")
elif i=="C":
sequence_C.append("G")
else:
sequence_C.append("C")
print(sequence_C)
The simplest thing to do, though, is to create a translation table.
sequence = "ACGTTAGCTAACG"
sequence_C = sequence.translate(str.maketrans("ATCG", "TAGC"))
答案3
得分: 0
你可以在循环的每次运行时创建一个新列表。将其提取出来，以便将元素附加到单个列表中。
sequence = ["A", "C", "G", "T", "T", "A", "G", "C", "T", "A", "A", "C", "G"]
sequence_C = []
for i in sequence:
if i == "A":
sequence_C.append("T")
elif i == "T":
sequence_C.append("A")
elif i == "C":
sequence_C.append("G")
else:
sequence_C.append("C")
print(sequence_C)
但有更好的方法。字典可以将一个值映射到另一个值。使用这种方法代替。
s_map = {"A": "T", "T": "A", "C": "G"} # 默认映射到 "C"
sequence_C = [s_map.get(s, "C") for s in sequence]
print(sequence_C)
英文:
You create a new list on each run of the loop. Pull that out to keep appending to a single list.
sequence=["A","C","G","T","T","A","G","C","T","A","A","C","G"]
sequence_C=[]
for i in sequence:
if i=="A":
sequence_C.append("T")
elif i=="T":
sequence_C.append("A")
elif i=="C":
sequence_C.append("G")
else:
sequence_C.append("C")
print(sequence_C)
But there is a better way. Dictionaries map one one value to another. Use that instead.
s_map = {"A":"T", "T":"A", "C":"G"} # w/ default "C"
sequence_C = [s_map.get(s, "C") for s in sequence]
print(sequence_C)
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