我正在尝试使用line.split（'\\ n）->无法识别行从类似文件的目录中打印一些关键行

Question

So this input file already has line breaks. It's the natural setting in which it's created. When I attempt to identify certain lines so that I can go back and call the values from said lines i get,

name = line[2]
IndexError: list index out of range

Any thoughts? I know there has to be an easy solution as this is fairly basic but I have sifted through every entry on splitting and splitting with ('\\n') and nothing has worked. Any help from you folks would be greatly appreciated!

-Ut prosim

Input :

    ID  rpmI_bact
    AC  TIGR00001
    DE  ribosomal protein L35

---

Script

for i in info.readlines():

    line = i.split('\n')
    id_hit = line[0]
    ac = line[1]
    name = line[2]

    print(name)

---

Error

name = line[2]
IndexError: list index out of range

Answer 1

First of all, when you do readlines , you will get back a list of all the lines your file, which will probably look something like this:

['    ID  rpmI_bact', '    AC  TIGR00001', '    DE  ribosomal protein L35']

If you take one of these values and then try to split on newlines, you won't get anything split:

'    ID  rpmI_bact'.split('\n')
['    ID  rpmI_bact']

Notice that the return value is a list with one element, so that's why you get your IndexError .

Now, it seems like you want to take each line and split on whitespace? If so, the way to do that is to use split(' ') , but this is going to give you potentially unreliable content back:

In [8]: for line in lines:
   ...:     print(line.split(' '))
   ...:     
['', '', '', '', 'ID', '', 'rpmI_bact']
['', '', '', '', 'AC', '', 'TIGR00001']
['', '', '', '', 'DE', '', 'ribosomal', 'protein', 'L35']

Notice how it's not obvious where the "content" is? We can solve this in a few ways. One is to introduce regexes, while the other way is to simply take the values that are not empty strings (note that empty strings in Python are False y values):

In [9]: bool("")
Out[9]: False
In [10]: for line in lines:
    ...:     print([elem for elem in line.split(' ') if elem])
    ...:     
['ID', 'rpmI_bact']
['AC', 'TIGR00001']
['DE', 'ribosomal', 'protein', 'L35']

Now you have to figure out what you want to do with those lists. I didn't really get that from the question, though.

Answer 2

I'd probably consider just making it a dictionary. Then you can query it by the 2 letter key. No need for the .readlines() either.

d = dict(line.strip().split('  ', 2) for line in info)

That should give you a dictionary looking like

{'AC': 'TIGR00001', 'DE': 'ribosomal protein L35', 'ID': 'rpmI_bact'}

Then you can just access the ID you're interested in

name = d['DE']