Python-正则表达式 : extract a list of tuples after a keyword from a text file

我想实现我建议的简化版本 here从 OpenFOAM blockMeshDict 文件导入一些顶点，然后 visualize them with FreeCAD .

我感兴趣的文件部分是 float (xi yi zi)元组列表，位于vertices关键字后的括号之间。该文件如下所示:

vertices 
( 
    (1 2 3) 
    (3 4 5) 
    ... 
) 

我能够从与 python 脚本相同的文件夹中读取文件:

import os 
os.chdir(os.path.dirname(__file__)) 
with open("blockMeshDict", "r") as f: 
    s=f.read() 

但是当我尝试提取 vertices 之后括号之间的内容时:

import re 
r1=re.search(r'vertices\n\((.*?)\)', s) 
print r1.group(1) 

我得到错误:

type 'exceptions.IndexError: no such group

我不知道怎么解决。最后我想要的是一个元组列表，如 [(x1,y1,z1),(x2,y2,z2)...] 如果你能帮助我，我将不胜感激知道如何在 Python 2.7 中实现它。

P.S. 可以在 this GitHub Gist 中找到这项工作的摘要。

请您参考如下方法:

这将是查找外部结构的主要正则表达式:\bvertices\s*\((\s*(?:\([^)]+\)\s*)+)\)

在此之前，我们将删除所有评论。

然后一个额外的正则表达式来提取顶点结构中的所有内容:\([^)]+\)

查看演示 here .

代码:

import re 
 
test_str = """ 
/*--------------------------------*- C++ -*----------------------------------*\ 
| =========                 |                                                 | 
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           | 
|  \\    /   O peration     | Version:  5                                     | 
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      | 
|    \\/     M anipulation  |                                                 | 
\*---------------------------------------------------------------------------*/ 
FoamFile 
{ 
    version     2.0; 
    format      ascii; 
    class       dictionary; 
    object      blockMeshDict; 
} 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // 
 
convertToMeters 0.001; 
 
vertices 
( 
    (-20.6 0 -0.5) 
    (-20.6 25.4 -0.5)  /* Some comment */ 
    (0 -25.4 -0.5) 
    (0 0 -0.5) 
    (0 25.4 -0.5) 
    (206 -25.4 -0.5) 
    (206 0 -0.5) 
    (206 25.4 -0.5) 
    (290 -16.6 -0.5) 
    (290 0 -0.5) 
    (290 16.6 -0.5) 
 
    (-20.6 0 0.5) 
    (-20.6 25.4 0.5) 
    (0 -25.4 0.5) 
    (0 0 0.5) 
    (0 25.4 0.5) 
    (206 -25.4 0.5) 
    (206 0 0.5) 
    (206 25.4 0.5) 
    (290 -16.6 0.5) 
    (290 0 0.5) 
    (290 16.6 0.5) 
  /*(1 2 3 4)*/ // Commented tuple 
  //(1 2 3 4) 
); 
 
/* vertices commented 
vertices 
( 
    (-20.6 0 -0.5) 
    (-20.6 25.4 -0.5) 
    (0 -25.4 -0.5) 
    (0 0 -0.5) 
    (0 25.4 -0.5) 
    (206 -25.4 -0.5) 
    (206 0 -0.5) 
    (206 25.4 -0.5) 
    (290 -16.6 -0.5) 
    (290 0 -0.5) 
    (290 16.6 -0.5) 
) 
*/ 
 
negY 
( 
    (2 4 1) 
    (1 3 0.3) 
); 
 
posY 
( 
    (1 4 2) 
    (2 3 4) 
    (2 4 0.25) 
); 
 
posYR 
( 
    (2 1 1) 
    (1 1 0.25) 
); 
 
 
blocks 
( 
    hex (0 3 4 1 11 14 15 12) 
    (18 30 1) 
    simpleGrading (0.5 $posY 1) 
 
    hex (2 5 6 3 13 16 17 14) 
    (180 27 1) 
    edgeGrading (4 4 4 4 $negY 1 1 $negY 1 1 1 1) 
 
    hex (3 6 7 4 14 17 18 15) 
    (180 30 1) 
    edgeGrading (4 4 4 4 $posY $posYR $posYR $posY 1 1 1 1) 
 
    hex (5 8 9 6 16 19 20 17) 
    (25 27 1) 
    simpleGrading (2.5 1 1) 
 
    hex (6 9 10 7 17 20 21 18) 
    (25 30 1) 
    simpleGrading (2.5 $posYR 1) 
); 
 
edges 
( 
); 
 
boundary 
( 
    inlet 
    { 
        type patch; 
        faces 
        ( 
            (0 1 12 11) 
        ); 
    } 
    outlet 
    { 
        type patch; 
        faces 
        ( 
            (8 9 20 19) 
            (9 10 21 20) 
        ); 
    } 
    upperWall 
    { 
        type wall; 
        faces 
        ( 
            (1 4 15 12) 
            (4 7 18 15) 
            (7 10 21 18) 
        ); 
    } 
    lowerWall 
    { 
        type wall; 
        faces 
        ( 
            (0 3 14 11) 
            (3 2 13 14) 
            (2 5 16 13) 
            (5 8 19 16) 
        ); 
    } 
    frontAndBack 
    { 
        type empty; 
        faces 
        ( 
            (0 3 4 1) 
            (2 5 6 3) 
            (3 6 7 4) 
            (5 8 9 6) 
            (6 9 10 7) 
            (11 14 15 12) 
            (13 16 17 14) 
            (14 17 18 15) 
            (16 19 20 17) 
            (17 20 21 18) 
        ); 
    } 
); 
// ************************************************************************* // 
""" 
 
# Clean comments: 
test_str = re.sub(r"//.*", '', test_str) 
test_str = re.sub(r"/\*.*?\*/", '', test_str, 0, re.DOTALL) 
 
# Match main group 
matches = re.findall(r"\bvertices\s*\((\s*(?:\([^)]+\)\s*)+)\)", test_str, re.MULTILINE | re.DOTALL) 
 
# Fetch tuples 
matches2 = re.findall(r"\([^)]+\)", matches[0], re.MULTILINE | re.DOTALL) 
print matches2 

解释:

\b        # word boundary 
vertices  # literal 'vertices' 
\s*       # 0 or more spaces (includes line feed/carriage return) 
\(        # literal '(' 
  (       # First capturing group 
    \s*   # Som spaces 
    (?:   # Group 
       \([^)]+\)   # literal '(' + any non-')' character 1 or more times + literal ')' 
       \s*         # extra spaces 
    )+    # repeated one or more times 
  ) 
\)        # literal ')' 

然后您将获得捕获的组并搜索 \([^)]+\)。这将找到顶点的实例。