不迭代文件？

Question

我试图在outfile（of）中找到以字母ATOM开头的行，然后对它做一些处理，但不幸的是它没有遍历文件。有人知道为什么吗？你知道吗

with open(args.infile, "r") as f, open(args.outfile, "w+") as of, open(args.reference,"r") as rf:
    for line in f:
        of.write(line)
    for line in rf:
        if line[0:3]== "TER":
            resnum = line[22:27]
            #resnum_1[resnum] = "TER"
    for line in of:
        if line [0:4]== "ATOM":
            res = line[22:27]
            if res == resnum:
                print res

Answer 1

丹尼尔的回答给了你正确的理由，但是错误的建议。你知道吗

要将数据刷新到磁盘，然后将指针移到文件的开头：

# If you're using Python2, this needs to be your first line:
from __future__ import print_function

with open('test.txt', 'w') as f:
    for num in range(1000):
        print(num, file=f)
    f.flush()
    f.seek(0)
    for line in f:
        print(line)

只要在of.flush(); of.seek(0)之前加上for line in of，你就可以随心所欲了。你知道吗

Answer 2

在第一个循环之后，of的文件点指向您编写的最后一行之后。当你试图从那里读的时候，你已经在文件的末尾了，所以没有什么可以循环的。你需要从头开始。你知道吗

with open(args.infile, "r") as f, open(args.outfile, "w+") as of, open(args.reference,"r") as rf:
    for line in f:
        of.write(line)
    for line in rf:
        if line[0:3]== "TER":
            resnum = line[22:27]
            #resnum_1[resnum] = "TER"
    of.seek(0)
    for line in of:
        if line [0:4]== "ATOM":
            res = line[22:27]
            if res == resnum:
                print res

Answer 3

有一个文件指针，指向最后写入或读取的位置。写入of后，文件指针位于文件末尾，因此无法读取任何内容。你知道吗

最好打开文件两次，一次用于写入，一次用于读取：

with open(args.infile, "r") as f, open(args.outfile, "w") as of:
    for line in f:
        of.write(line)

with open(args.reference,"r") as rf:
    for line in rf:
        if line[0:3]== "TER":
            resnum = line[22:27]
            #resnum_1[resnum] = "TER"

with open(args.outfile, "r") as of
    for line in of:
        if line [0:4]== "ATOM":
            res = line[22:27]
            if res == resnum:
                print res