这里是importa nt格式的数字，而不是数值。有数字，点和一个或多个数字，你应该写在正则表达式中：\ d \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\如何提取精确的列的方法是先使用awk。
这样你可以设置列号：

  $ var = 3 
 $ ls -l | awk'{print $'$ var'}'
 

---

我不认为这是一个任务bash（我不说这是不可能的），所以我写了我的解决方案在python中：

  import re，sys 

 num = {} 
 files = ['file1'，'file2'] 

文件中的文件：
f = open（file，'r'）
 for f.readlines（）中的行：
 cont = re.match（r（\ d + \.\\\d +）\s （。*），line）
 if cont！= None：
 if float（cont.group（1））not in num：
 num [float（cont.group（1） ）] = [] 
 num [float（cont.group（1））]。append（cont.group（2））
 f.close（）

 for key in：
 sys.stdout.write（str（key）+''）
 print num [key] 
 

---

file1：

  0.5 x1 
 0.8 x2 
 0.3 x3 
 

file2：

  1.3 y1 
 0.5 y2 
 0.0 y3 
 $ b 
 $ > 0.5 ['x1'，'y2'] 
 0.0 ['y3'] 
 1.3 ['y1'] 
 0.3 ['x3'] 
 0.8 ['x2' ] 
 

I need help in extracting one column of numbers from many different files and display it in an output file.

Specifically, I want to extract the second column ($2) from each file, file1.txt, file2.txt etc., according the the value of the first column, then place all extracted columns in a one file, out.txt.

The problem is that the first column has different intervals in each file:

file:

0.50 x1
1.25 x2
1.50 x3
1.75 x4
2.00 x5

file2:

0.25 y1
0.50 y2
1.00 y3
1.25 y4
2.00 y5

Desired output:

0.25    y1
0.50 x1 y2
1.00    y3
1.25 x2 y4
1.50 x3
1.75 x4
2.00 x5 y5

Here is important format of the number, not value. There is number, dot and one or more numbers, which you should write in regex: \d\.\d+

If your file has more columns the best way how to extract exact column is use awk first. This way you may set column number:

$ var=3
$ ls -l | awk '{print $'$var'}'

---

I dont think that it is a task for bash (I dont say that it is not possible), so I wrote my solution in python:

import re, sys

num = {}
files = ['file1', 'file2']

for file in files:
    f = open(file,'r')
    for line in f.readlines():
        cont = re.match(r"(\d+\.\d+)\s(.*)", line)
        if cont != None:
            if float(cont.group(1)) not in num:
                num[float(cont.group(1))] = []
            num[float(cont.group(1))].append(cont.group(2))
    f.close()

for key in num:
    sys.stdout.write(str(key)+' ')
    print num[key]

---

file1:

0.5 x1
0.8 x2
0.3 x3

file2:

1.3 y1
0.5 y2
0.0 y3

output:

0.5 ['x1', 'y2']
0.0 ['y3']
1.3 ['y1']
0.3 ['x3']
0.8 ['x2']