<p>这里的问题似乎是您在文件对象中迭代了两次。在Python中,文件对象的工作方式非常类似于遍历每一行的指针。如果不向后移动指针,它就没有可读取的内容。在</p>
<p>您需要做的是使用<code>.seek</code>函数将该指针移回起始位置。例如,假设你有一个<code>file_to_read.txt</code>和你的<code>python_script.py</code>。在</p>
<p><strong>文件_阅读.txt</strong></p>
<pre><code>Hello! My name is Bob and I can't think of anything to
put in this file so I'm blabbering on about nonsense
in hopes that you won't realise that this text is not
important but the code in the actually file, though I
think that you wouldn't mind reading this long file.
</code></pre>
<p><strong>Python_脚本.py</strong></p>
^{pr2}$
<p>如果要运行这段代码(并且没有出现有关目录的错误),则只需打印一次<code>file_to_read.txt</code>。要解决这个问题,您只需在阅读之间添加一个<code>f.seek(0, 0)</code>。例如:</p>
<pre><code>f = open("file_to_read.txt", "r")
for line in f: print line
f.seek(0, 0)
for lien in f: print line
</code></pre>
<p>现在,回到您的上下文,您可以看到这是如何应用于您的代码的:</p>
<pre><code>import sys
# Here is your reading of file
blastfile = open(sys.argv[1],"r")
column1list = []
# Here is the first time you read the file
for line in blastfile:
b = line.split()[0]
column1list.append(b)
# Add a line to move back to the start before the
# next reading
blastfile.seek(0, 0)
uniqcolumn1 = list(set(column1list))
for val in uniqcolumn1:
# Move the counter inside to refresh it after every iteration
counter = 0
# Here is the second time you read your file
for line in blastfile:
while counter <= 10:
if line.startswith(val):
print line
counter += 1
# Since you are going to read the file the next iteration,
# .seek the file
blastfile.seek(0, 0)
</code></pre>
<p><strong>编辑</strong></p>
<p>这是代码的后半部分,已修复。你也可以这样做:</p>
<pre><code>for val in uniqcolumn1:
# Move the counter in
counter = 0
# Move the while loop out
while counter <= 10:
for line in blastfile:
if line.startswith(val):
print line,
counter += 1
blastfile.seek(0, 0)
</code></pre>
<p>这样做的好处是for循环提前终止,它不会读取整个文件。在</p>
<p>另一种方法是:</p>
<pre><code>for val in uniqcolumn1:
# Move counter in
counter = 0
# Remove while statement
for line in blastfile:
# Add additional condition to if statement
if line.startswith(val) and counter <= 10:
print line,
counter += 1
elif counter > 10:
break
blastfile.seek(0, 0)
</code></pre>
<p>这样做的好处是看起来更简单。在</p>