我正在为Web应用程序编写一个日志文件查看器,为此我想通过日志文件的行分页.文件中的项目是基于行的,底部是最新项目.
所以我需要一种tail()方法,可以n从底部读取行并支持偏移量.我想出的是这样的:
def tail(f, n, offset=0):
"""Reads a n lines from f with an offset of offset lines."""
avg_line_length = 74
to_read = n + offset
while 1:
try:
f.seek(-(avg_line_length * to_read), 2)
except IOError:
# woops. apparently file is smaller than what we want
# to step back, go to the beginning instead
f.seek(0)
pos = f.tell()
lines = f.read().splitlines()
if len(lines) >= to_read or pos == 0:
return lines[-to_read:offset and -offset or None]
avg_line_length …我在Python 2.5中有一个监听beanstalk队列的应用程序.它在我测试的所有机器上都能正常工作,除了我新购买的MacBook Pro.
在那台计算机上,当我尝试运行它时,我收到此错误:
Traceback (most recent call last):
File "jobs.py", line 181, in <module>
Jobs().start()
File "jobs.py", line 154, in start
self.jobQueue = Queue()
File "src/utils/queue.py", line 16, in __init__
self.connection = serverconn.ServerConn(self.server, self.port)
File "src/beanstalk/serverconn.py", line 25, in __init__
self.poller = select.poll()
AttributeError: 'module' object has no attribute 'poll'
serverconn.py具有以下导入:
import socket, select
当我尝试从命令行运行它时,它也会失败:
Python 2.5.1 (r251:54863, Jul 23 2008, 11:00:16)
[GCC 4.0.1 (Apple Inc. build 5465)] on darwin
Type "help", "copyright", "credits" or "license" for more information. …我没有真正找到与我的问题相关的示例，因为我不了解 Pandas，所以我将其发布在这里。如果不清楚或已经得到答复，请告诉我。
我有一个 CSV 输入，我像这样导入
def import_csv(csvfilename):
data = []
with open(csvfilename, "r", encoding="utf-8", errors="ignore") as scraped:
reader = csv.reader(scraped, delimiter=',')
row_index = 0
for row in reader:
if row: # avoid blank lines
row_index += 1
columns = [str(row_index), row[0], row[1], row[2]]
data.append(columns)
return data
我用 input_rows 索引行（可能有更好的方法吗？）
输入示例：
[['1',
'[FirstValue]',
'FirstText',
'AB'],
[...]
['12',
"['LastValue']",
"LastText",
'YZ']]
我正在寻找此输入列表的最后一行。有没有一种简单的方法可以做到这一点，而无需迭代所有行？
谢谢 ！