python - Python 中的列表仅避免第一个负数元素

Question

我正在尝试比较 numbers.txt 文件中的数字。困扰我的是 Python 中的负索引属性，其中负数实际上意味着从右到左阅读。

有没有办法只忽略第一次比较？我在哪里输出没有以前的数字(参见所需的输出)

重要的是我无法更改我的 numbers.txt 文件。这些是我从另一个函数自动生成的。

$ cat numbers.txt

1
2
3
4
5

代码:

with open('numbers.txt') as file:
    lines = file.read().splitlines()
    print lines
    for i in range(len(lines)):
        previous_number = lines[i-1]
        current_number = lines[i]
        print "current Nr: ", current_number
        print "previous Nr: ", previous_number
        if current_number > previous_number:
            print " current Nr is larger"
        else:
            print "current Nr is smaller"

输出:

['1', '2', '3', '4', '5']
current Nr:  1
previous Nr:  5
current Nr is  smaller
current Nr:  2
previous Nr:  1
 current Nr is larger
current Nr:  3
previous Nr:  2
 current Nr is larger
current Nr:  4
previous Nr:  3
 current Nr is larger
current Nr:  5
previous Nr:  4
 current Nr is larger

期望的输出

['1', '2', '3', '4', '5']
current Nr:  1
previous Nr:  There is no previous!
current Nr is  none
current Nr:  2
previous Nr:  1
 current Nr is larger
current Nr:  3
previous Nr:  2
 current Nr is larger
current Nr:  4
previous Nr:  3
 current Nr is larger
current Nr:  5
previous Nr:  4
 current Nr is larger

Answer 1

您可以使用enumerate 来检查索引

for i, value in enumerate(lines):
  previous_number = "None"
  CurrentNrText = "None"
  if i != 0:
    previous_number = lines[i-1]
    if current_number > previous_number:
       CurrentNrText = " current Nr is larger"
     else:
       CurrentNrText = "current Nr is smaller"

  current_number = lines[i]
  print("current Nr: ", current_number)
  print("previous Nr: ", previous_number)
  print(CurrentNrText)