Python实现简单过滤文本段的方法

本文实例讲述了Python实现简单过滤文本段的方法。分享给大家供大家参考,具体如下:

一、问题:

如下文本:

## Alignment 0: score=397.0 e_value=8.2e-18 N=9 scaffold1&scaffold106 minus

0- 0: 10026549 10007782 2e-75

0- 1: 10026550 10007781 8e-150

0- 2: 10026552 10007780 1e-116

0- 3: 10026555 10007778 0

0- 4: 10026570 10007768 0

0- 5: 10026579 10007758 4e-15

0- 6: 10026581 10007738 2e-44

0- 7: 10026587 10007734 9e-145

0- 8: 10026591 10007732 2e-147

## Alignment 1: score=2304.0 e_value=1e-164 N=47 scaffold1&scaffold107 minus

1- 0: 10026836 10007942 2e-84

1- 1: 10026839 10007940 0

1- 2: 10026840 10007938 0

1- 3: 10026842 10007937 9e-82

1- 4: 10026843 10007935 7e-79

1- 5: 10026847 10007933 3e-119

1- 6: 10026850 10007932 2e-87

1- 7: 10026854 10007928 5e-22

1- 8: 10026855 10007927 3e-101

1- 9: 10026856 10007925 1e-106

1- 10: 10026857 10007924 0

1- 11: 10026858 10007922 9e-123

1- 12: 10026859 10007921 1e-80

1- 13: 10026860 10007920 8e-104

1- 14: 10026862 10007918 4e-25

1- 15: 10026863 10007917 0

1- 16: 10026864 10007912 4e-40

1- 17: 10026865 10007911 0

1- 18: 10026866 10007910 7e-122

1- 19: 10026867 10007908 2e-25

1- 20: 10026868 10007907 0

1- 21: 10026869 10007905 0

1- 22: 10026870 10007904 3e-150

1- 23: 10026871 10007903 5e-77

1- 24: 10026874 10007901 0

1- 25: 10026875 10007897 0

1- 26: 10026876 10007896 0

1- 27: 10026877 10007894 0

1- 28: 10026880 10007893 3e-52

1- 29: 10026881 10007892 0

1- 30: 10026882 10007891 0

1- 31: 10026883 10007890 0

1- 32: 10026886 10007889 1e-50

1- 33: 10026887 10007888 6e-157

1- 34: 10026888 10007887 0

1- 35: 10026889 10007884 0

1- 36: 10026890 10007883 2e-18

1- 37: 10026891 10007882 9e-64

1- 38: 10026892 10007881 0

1- 39: 10026895 10007880 0

1- 40: 10026898 10007875 0

1- 41: 10026900 10007874 0

1- 42: 10026901 10007873 0

1- 43: 10026902 10007871 2e-123

1- 44: 10026903 10007870 0

1- 45: 10026905 10007869 0

1- 46: 10026909 10007868 1e-81

## Alignment 2: score=811.0 e_value=3.3e-43 N=17 scaffold1&scaffold111 minus

2- 0: 10026595 10007449 6e-40

2- 1: 10026599 10007448 4e-90

2- 2: 10026600 10007447 0

2- 3: 10026601 10007444 9e-55

2- 4: 10026603 10007438 4e-78

2- 5: 10026604 10007434 9e-122

2- 6: 10026606 10007432 2e-162

2- 7: 10026607 10007427 0

2- 8: 10026608 10007426 0

2- 9: 10026612 10007417 0

2- 10: 10026613 10007415 8e-128

2- 11: 10026614 10007414 3e-64

2- 12: 10026615 10007409 0

2- 13: 10026616 10007406 0

2- 14: 10026617 10007403 1e-171

2- 15: 10026618 10007402 0

2- 16: 10026619 10007397 7e-18

........

要求:如果Alignment后面少于20行,把整个的去掉

二、实现方法:

python代码:

#!/usr/bin/python

sum = 0

sumdata = []

FD = open("/root/data.txt","r")

line = FD.readline()

while line:

if line.find("Alignment") == 3:

if sum >= 20:

for i in sumdata:

print i,

sum=0

sumdata=[line]

else:

sum = sum + 1

sumdata.append(line)

line=FD.readline()

if len(line) == 0:

if sum >= 20:

for i in sumdata:

print i,

附:

perl代码

#!/usr/bin/perl

open(FD,"/root/data.txt");

while (){

if ($_ =~ /Alignment/){

if($sum >= 20){

print @sumdata;}

$sum=0;

@sumdata=($_);}

else{

$sum++;

push(@sumdata,$_);}

}

print @sumdata if $sum >=20;

close(FD);

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