為什么不能更改列表項(xiàng)的類型或值？a = ['3.465759','2.8797','9.23544']for each in a: print(each) each = round(float(each),3) + 2 print(a)結(jié)果是 ['3.465759', 2.8797, '9.23544']
4 回答
萬千封印
TA貢獻(xiàn)1891條經(jīng)驗(yàn) 獲得超3個贊
eacha是在下一次迭代中取下一個值的循環(huán)變量。將轉(zhuǎn)換后的值存儲在另一個列表中。
a = ['3.465759','2.8797','9.23544']
b = []
for each in a:
print(each)
each = round(float(each),3) + 2
b.append(each)
print(b)
輸出：
3.465759
2.8797
9.23544
[5.466, 4.88, 11.235]
或者
如果你想就地修改列表，那么
a = ['3.465759','2.8797','9.23544']
for i in range(len(a)):
each = a[i]
print(each)
each = round(float(each),3) + 2
a[i] = each
print(a)
或者
使用列表理解
[round(float(each),3) + 2 for each in a]
九州編程
TA貢獻(xiàn)1785條經(jīng)驗(yàn) 獲得超4個贊
您可以使用地圖：
a?=?['3.465759','2.8797','9.23544'] float_list?=?list(map(float,?a)) print(float_list)
輸出：
[3.465759,?2.8797,?9.23544]
慕碼人8056858
TA貢獻(xiàn)1803條經(jīng)驗(yàn) 獲得超6個贊
a = ['3.465759','2.8797','9.23544']
result = []
for each in a:
each = round(float(each),3) + 2
result.append(each)
print(result)
Output: [5.466, 4.88, 11.235]
這是你想要的？
慕婉清6462132
TA貢獻(xiàn)1804條經(jīng)驗(yàn) 獲得超2個贊
你沒有改變a，當(dāng)你進(jìn)行轉(zhuǎn)換時，請確保更改值：即：
a = ['3.465759','2.8797','9.23544']
for i in range(len(a)):
each = a[i]
print(each)
each = round(float(each),3) + 2
a[i] = each
print(a)
或者
a = ['3.465759','2.8797','9.23544']
for i, each in enumerate(a):
print(each)
each = round(float(each),3) + 2
a[i] = each
print(a)
3.465759
2.8797
9.23544
[5.466, 4.88, 11.235]
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