Python 如何在更正if语句之前打印X行
我对Python非常陌生,对我在众多网页中找到的东西只有零碎的知识 也就是说,我试图在一个文件(~10k行)中搜索我编写的一组类似“过滤器”的条件,然后我希望它打印出符合条件的行,以及一行之前的X行数 我已经创建了以下脚本来打开所述文件,逐行迭代,并将符合筛选条件的行打印到输出文件中,但是我对如何将其合并到当前脚本中感到困惑Python 如何在更正if语句之前打印X行,python,python-2.7,list,tuples,enumeration,Python,Python 2.7,List,Tuples,Enumeration,我对Python非常陌生,对我在众多网页中找到的东西只有零碎的知识 也就是说,我试图在一个文件(~10k行)中搜索我编写的一组类似“过滤器”的条件,然后我希望它打印出符合条件的行,以及一行之前的X行数 我已经创建了以下脚本来打开所述文件,逐行迭代,并将符合筛选条件的行打印到输出文件中,但是我对如何将其合并到当前脚本中感到困惑 import os output_file = 'Output.txt' filename = 'BigFile.txt' numLi
import os
output_file = 'Output.txt'
filename = 'BigFile.txt'
numLines = 0
numWords = 0
numChrs = 0
numMes = 0
f1 = open(output_file, 'w')
print 'Output File has been Opened'
with open(filename, 'r') as file:
for line in file:
wordsList = line.split()
numLines += 1
numWords += len(wordsList)
numChrs += len(line)
if "X" in line and "Y" not in line and "Z" in line:
numMes += 1
print >>f1, line
print 'Object found and Catalogued in Output.txt'
print "Lines: %i\nWords: %i\nCharacters: %i" % (numLines, numWords, numChrs)
print >>f1, "Lines: %i\nWords: %i\nCharacters: %i" % (numLines, numWords, numChrs)
print "There are a total of %i thing in this file" % (numMes)
print >>f1, "There are a total of %i things in this file" % (numMes)
f1.close()
print 'Output Files have been Closed'
我的第一个猜测是使用line.enumeration
,但我不认为我可以直接用line-5
这样的语句来打印行之前的5行:
lines = f1.enumeration()
if "blah blah" in line and "so so" not in line:
print >>f1, lines
print >>f1, [lines - 5]
最好的部分还在后面,因为我必须获取Output.txt文件并与另一个文件进行比较,以输出两个文件中的匹配条件。。。但是一步一个脚印,对吗
-也可以随意添加“适当”技术的简介。。。我相信这个脚本可以写得更好,所以请务必告诉我我做错了什么
提前感谢您的帮助
更新:
由于以下帮助,我们已成功实施修复:
import os
output_file = 'Output.txt'
filename = 'BigFile.txt'
numLines = 0
numWords = 0
numChrs = 0
numMulMes = 0
last5 = []
f1 = open(output_file, 'w')
print 'Output Files have been Opened'
with open(filename, 'r') as file:
for line in file:
wordsList = line.split()
numLines += 1
numWords += len(wordsList)
numChrs += len(line)
last5[:] = last5[-5:]+[line]
if "X" in line and "Y" not in line and "Z" not in line:
del last5[1:5] ###the missing piece of the puzzle!
numMulMes += 1
print >>f1, last5
print 'Object found and Catalogued in Output.txt'
print "Lines: %i\nWords: %i\nCharacters: %i" % (numLines, numWords, numChrs)
print >>f1, "Lines: %i\nWords: %i\nCharacters: %i" % (numLines, numWords, numChrs)
print "There are a total of %i messages in this file" % (numMulMes)
print >>f1, "There are a total of %i messages in this file" % (numMulMes)
f1.close()
f3.close()
print 'Output Files have been Closed'
我一直试图通过另一个单独的脚本修改输出文件,在最长的时间里,我一直在与str vs lst操作和错误问题作斗争。只是决定回到原来的剧本,一时兴起把它扔进去,维奥拉
谢谢你把我推向了正确的方向,从那里很容易就明白了 你自己解决了大部分问题(计算单词、行数、行号等)
-在浏览文件时,您可以简单地记住最后n行
例如:
t = """"zero line
one line
two line
three line
four line
five line
six line
seven line
eight line
"""
last5 = [] # memory cell
for l in t.split("\n"): # similar to your for line in file:
last5[:] = last5[-4:]+[l] # keep last 4 and add current line, inplace list mod
if "six" in l:
print last5
您还可以查看并指定最大长度(需要导入)
输出:
# list version
['two line', 'three line', 'four line ', 'five line ', 'six line']
# deque version
deque(['two line', 'three line', 'four line ', 'five line ', 'six line'], maxlen=5)
你自己解决了大部分问题(计算单词、行数、行号等)
-在浏览文件时,您可以简单地记住最后n行
例如:
t = """"zero line
one line
two line
three line
four line
five line
six line
seven line
eight line
"""
last5 = [] # memory cell
for l in t.split("\n"): # similar to your for line in file:
last5[:] = last5[-4:]+[l] # keep last 4 and add current line, inplace list mod
if "six" in l:
print last5
您还可以查看并指定最大长度(需要导入)
输出:
# list version
['two line', 'three line', 'four line ', 'five line ', 'six line']
# deque version
deque(['two line', 'three line', 'four line ', 'five line ', 'six line'], maxlen=5)
我把东西输出到字典,而不是写入文件。处理完整个文件后,汇总数据字典将以json
的形式转储到文件中。使用Artner的测试文件
import os
import json
output_file = 'Output.txt'
filename = 'BigFile.txt'
#initiate output container
outDict = {}
for fields in ['numLines', 'numWords', 'numChrs', 'numMes']:
outDict[fields] = 0
outDict['lineNum'] = []
with open(filename, 'r') as file:
for line in file:
wordsList = line.strip().split("\s")
outDict['numLines'] += 1
outDict['numWords'] += len(wordsList)
outDict['numChrs'] += len(line)
#find items in the line
if "t" in line:
outDict['numMes'] += 1
#save line number
outDict['lineNum'].append(outDict['numLines'])
#save line content
outDict['lineList'].append(line)
#record output
with open(output_file, 'w') as f1:
f1.write(json.dumps(outDict))
##print lines of desire
#x number of lines before
x=5
with open(filename, 'r') as file:
for i, line in enumerate(file):
#iterate over line numbers for which condition is met
for j in range(0,len(outDict['lineNum'])):
#if line number is between found line num and line num minus x, print
if (outDict['lineNum'][j]-x) <= i <= outDict['lineNum'][j]:
print(line)
导入操作系统
导入json
输出文件='output.txt'
文件名='BigFile.txt'
#启动输出容器
outDict={}
对于['numLines'、'numWords'、'numChrs'、'numMes'中的字段:
outDict[字段]=0
outDict['lineNum']=[]
打开(文件名为“r”)作为文件:
对于文件中的行:
wordsList=line.strip().split(“\s”)
outDict['numLines']+=1
outDict['numWords']+=len(单词列表)
输出['numChrs']+=len(行)
#查找行中的项目
如果“t”在直线上:
输出['numes']+=1
#保存行号
outDict['lineNum'].append(outDict['numLines'])
#保存行内容
outDict['lineList'].追加(行)
#记录输出
打开(输出_文件“w”)为f1时:
f1.write(json.dumps(outDict))
##印刷欲望的线条
#x之前的行数
x=5
打开(文件名为“r”)作为文件:
对于i,枚举(文件)中的行:
#迭代满足条件的行号
对于范围(0,len)(outDict['lineNum'])内的j:
#如果行号介于找到的行数和行数减去x之间,则打印
如果(outDict['lineNum'][j]-x)不是写入文件,而是将内容输出到字典。处理完整个文件后,汇总数据字典将以json
的形式转储到文件中。使用Artner的测试文件
import os
import json
output_file = 'Output.txt'
filename = 'BigFile.txt'
#initiate output container
outDict = {}
for fields in ['numLines', 'numWords', 'numChrs', 'numMes']:
outDict[fields] = 0
outDict['lineNum'] = []
with open(filename, 'r') as file:
for line in file:
wordsList = line.strip().split("\s")
outDict['numLines'] += 1
outDict['numWords'] += len(wordsList)
outDict['numChrs'] += len(line)
#find items in the line
if "t" in line:
outDict['numMes'] += 1
#save line number
outDict['lineNum'].append(outDict['numLines'])
#save line content
outDict['lineList'].append(line)
#record output
with open(output_file, 'w') as f1:
f1.write(json.dumps(outDict))
##print lines of desire
#x number of lines before
x=5
with open(filename, 'r') as file:
for i, line in enumerate(file):
#iterate over line numbers for which condition is met
for j in range(0,len(outDict['lineNum'])):
#if line number is between found line num and line num minus x, print
if (outDict['lineNum'][j]-x) <= i <= outDict['lineNum'][j]:
print(line)
导入操作系统
导入json
输出文件='output.txt'
文件名='BigFile.txt'
#启动输出容器
outDict={}
对于['numLines'、'numWords'、'numChrs'、'numMes'中的字段:
outDict[字段]=0
outDict['lineNum']=[]
打开(文件名为“r”)作为文件:
对于文件中的行:
wordsList=line.strip().split(“\s”)
outDict['numLines']+=1
outDict['numWords']+=len(单词列表)
输出['numChrs']+=len(行)
#查找行中的项目
如果“t”在直线上:
输出['numes']+=1
#保存行号
outDict['lineNum'].append(outDict['numLines'])
#保存行内容
outDict['lineList'].追加(行)
#记录输出
打开(输出_文件“w”)为f1时:
f1.write(json.dumps(outDict))
##印刷欲望的线条
#x之前的行数
x=5
打开(文件名为“r”)作为文件:
对于i,枚举(文件)中的行:
#迭代满足条件的行号
对于范围(0,len)(outDict['lineNum'])内的j:
#如果行号介于找到的行数和行数减去x之间,则打印
如果(outDict['lineNum'][j]-x)这里的解决方案与@PatricArtner建议的相同,但是使用了环形缓冲区。它可能(也可能不是,我没有检查)在处理大文件时工作得更快。
想法很简单:我们可以创建一个具有所需大小(您应该保留的行数)的列表和一个当前录制位置的计数器cnt
。对于每一条新线,我们应该将cnt增加1,并根据缓冲区的大小进行模运算。因此,cnt
在列表中循环。例如,如果列表大小为5cnt=(cnt+1)%5
将给出0 1 2 3 4 0 1 2
,依此类推。每一步cnt
都将指向列表中最旧的数据,这些数据将被新数据取代。下面是一个实现示例
t = """"zero line
six line - surprize
one line
two line
three line
four line
five line
six line
seven line
eight line
"""
last5 = [None,None,None,None,None]
cnt = 0
for l in t.split("\n"):
last5[cnt]=l
if 'six' in l:
print last5[(cnt+1)%5]
print last5[(cnt+2)%5]
print last5[(cnt+3)%5]
print last5[(cnt+4)%5]
print last5[(cnt+0)%5]
print
cnt = (cnt+1)%5
输出非常简单:
None
None
None
"zero line
six line - surprize
two line
three line
four line
five line
six line
注意:如果你从一个文件中读取,而该文件非常大,并且需要保留的字符串非常大(例如,基因序列),并且你的病情不会经常触发,请注意,不要在内存中保留字符串。在文件中创建位置列表
$ grep -B 5 six test.txt
one line
two line
three line
four line
five line
six line