Question

我是编程和学习python的新手，参考书 Python Programming Fundamentals 。这是我要处理的问题之一：

1：请求用户输入数字列表。

2：然后输出0到100之间的数字。

以下是我的代码：

s = input("Please enter a list of numbers:") # request user to input a list of numbers
lst = s.split()                              # Now lst is a list of strings.
    output = []                              # Here is the beginning of the accumulator pattern

for e in lst:
    if float(e) > 0 and float(e) < 100 :     # inbetween 0 and 100
        output = output.append(float(e))
    else:
        output = output

print("The number between 0 and 100 are ", output)

错误是：

File "c:\Users\HKGGAIT001\Desktop\1.py", line 7, in <module>
  output = output.append(float(e))
builtins.AttributeError: 'NoneType' object has no attribute 'append

Answer 1

假设您在Python 2.x。

，您当前的代码有几个问题

使用input会导致Python尝试评估用户输入，这会导致问题，因为您希望它们输入数字列表。 raw_input只会向您提供用户输入的内容，而不会尝试解析它。
list.append就位，这意味着函数调用的副作用只会在调用它的对象上执行追加，而不是返回一个新对象。

试试这个：

s = raw_input("Please enter a list of numbers: ") 
lst = s.split()
output = []

for e in lst:
    if float(e) > 0 and float(e) < 100 :     # inbetween 0 and 100
         output.append(float(e))

print("The number between 0 and 100 are ", output)

Answer 2

假设您正在使用Python3（因为.split（）不太可能在Python2中成功）

这部分没问题

s = input("Please enter a list of numbers:") # request user to input a list of numbers
lst = s.split()                              # Now lst is a list of strings.
output = []                              # Here is the beginning of the accumulator pattern

你可以像这样编写循环

for e in lst:
    if 0 < float(e) < 100 :     # inbetween 0 and 100
         output.append(float(e))

请注意，有两个比较。隐含and。这称为chained comparison

使用list comprehension

可以将此模式缩减为一行

output = [float(e) for e in lst if 0 < float(e) < 100]

但现在我们需要使用float(e)两次

我们可以使用其他list comprehension将lst列为float

s = input("Please enter a list of numbers:") # request user to input a list of numbers
lst = [float(e) for e in s.split()]          # Now lst is a list of floats.
output = [e for e in lst if 0 < e < 100]

由于我们只需要迭代lst一次，因此微小的变化会使其成为generator expression。所以你的最终计划可能是

s = input("Please enter a list of numbers:") # request user to input a list of numbers
lst = (float(e) for e in s.split())          # Now lst is a generator of floats.
output = [e for e in lst if 0 < e < 100]
print("The number between 0 and 100 are ", output)

Answer 3

     s = str(input("Please enter a list of numbers:")) 
     lst = s.split()                              
    output = [] 
    for e in lst:
          if float(e) > 0 and float(e) < 100 :    
    output.append(float(e))
    print("The number between 0 and 100 are ", output)
    else:
    print("The number less than 0 or greter than 100 ", e)

Answer 4

s = input("Please enter a list of numbers:")
output = [each for each in s if each > 0.0 and each < 100.0]
print("The number between 0 and 100 are ", output)

Python列表编号与选择

4 个答案: