使用python读取nastran几何文件 [英] Reading nastran geometry file with python

问题描述

我正在尝试使用python解析nastran文件的几何信息.我目前的尝试使用NumPy以及正则表达式.快速读取数据并确保结果为NumPy数组非常重要.

I am trying to parse the geometry information of a nastran file using python. My current attempts use NumPy as well as regular expressions. It is important to read the data fast and that the result is a NumPy array.

一个nastran文件如下所示:

A nastran file can look like the following:

GRID           1        3268.616-30.0828749.8656    
GRID           2        3268.781  -3.-14749.8888
GRID           3        3422.488580.928382.49383
GRID           4        3422.488     10.-2.49383
...

我只对文件的右侧部分感兴趣.在那里，信息分别以x，y和z坐标为8个字符的块的形式出现.上面坐标的常见表示形式是

I am only interested in the right part of the file. There the information is present in chunks of 8 characters for the x, y and z coordinates respectively. A common representation of the coordinates above would be

3268.616, -30.0828, 749.8656    
3268.781,  -3.e-14, 749.8888
3422.488, 580.9283, 82.49383
3422.488,      10., -2.49383

到目前为止我尝试过的事情

到目前为止，我一直尝试使用正则表达式和NumPy来避免各种python for循环，以尽可能快地处理数据.将完整的文件读入内存并将其存储在fContent变量中后，我尝试过:

What I tried so far

Up until now, I tried to use regular expressions and NumPy to avoid all kinds of python for loops to be as fast a possible about dealing with the data. After reading the complete file into memory and store it in the fContent variable I tried:

vertices = np.array(re.findall("^.{24}(.{8})(.{8})(.{8})", fContent, re.MULTILINE), dtype=float)

但是，这对于-3.-14表达式是不够的.一种解决方案是循环遍历正则表达式的结果字符串元组，并将所有.-替换为.e-，然后从字符串元组列表创建NumPy数组. (未在上面的代码中显示).但是，我认为这种方法会很慢，因为它涉及对所有找到的正则表达式元组进行循环并执行替换.

However, this falls short for the -3.-14 expressions. A solution would be to loop over the resulting string tuples of the regex and substitude all .- with .e- and then create the NumPy array from the list of string tuple. (Not shown in the code above). However, I think that this approach would be slow since it involves a loop over all found tuples of the regular expression and perform a substitution.

我正在寻找读取数据的任何快速方法.我目前的希望是能成功处理"-3.-14"问题的智能正则表达式.如果.不在8个字符块的末尾，则正则表达式需要将所有.-字符替换为.e-，但仅 .到目前为止，我还无法创建这样的正则表达式.但是正如我所说，任何其他快速读取数据的方式也非常受欢迎.

I am looking for any fast way to read in the data. My current hopes are on a smart regular expression that successfully deals with the "-3.-14" problem. The regex would need to substitute all .- characters with .e- but only if the . is not at the end of an 8 character block. Up until now, I was not able to create such a regular expression. But as I said, any other fast way of reading in the data is also very welcome.

推荐答案

这样的工作正常吗?匹配.-并替换为.e-.

Would something like this work fine? Match the .- and replace with .e-.

正则表达式:(\.-)(?!(.{7})?$)

演示

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