从Common Lisp中的文本文件读取数组 [英] Reading an array from a text file in Common Lisp

问题描述

我正在尝试从文本文件中读取Lisp中的数据(实际上是一个数组). 我尝试使用with-open-file和read-line东西，但无法实现我的目标.我正在寻找的内容等同于在MATLAB中执行data=load('filename.txt')，因此我得到一个名为data的数组，该数组已将所有信息加载到filename.txt中.

I am trying to read data (which is actually an array) in Lisp from a text file. I tried to use with-open-file and read-line stuff but could not achieve my goal. What I am looking for is equivalent to doing data=load('filename.txt') in MATLAB, so that I get an array called data which has loaded the whole information in filename.txt.

文本文件的格式为

1.0 2.0 3.0 ...
1.5 2.5 3.5 ...
2.0 3.0 4.0 ...
 .....

大小也可能有所不同.提前非常感谢.

The size may also vary. Thanks a lot in advance.

推荐答案

做到这一点的基本方法是使用with-open-file获取输入流，read-line在loop中获取行，(来自相同名称的库)将其拆分为字段，而parse-number(来自相同名称的库)将字符串转换为数字.提到的所有库都可以从 Quicklisp 中获得.

The basic way to do that is to use with-open-file for getting the input stream, read-line in a loop to get the lines, split-sequence (from the library of the same name) to split it into fields, and parse-number (from the library of the same name) to transform the strings into numbers. All libraries mentioned are available from Quicklisp.

只是为了入门，这是一个未经验证的简单版本:

Just to get you started, this is a simple version without validation:

(defun load-array-from-file (filename)
  (with-open-file (in filename
                      :direction :input)
    (let* ((data-lol (loop :for line := (read-line in nil)
                           :while line
                           :collect (mapcar #'parse-number:parse-number
                                            (cl-ppcre:split "\\s+" line))))
           (rows (length data-lol))
           (columns (length (first data-lol))))
      (make-array (list rows columns)
                  :initial-contents data-lol))))

您应该添加一些检查，并考虑如果不满足要求您想得到什么:

You should add some checks and think about what you want to get in case they are not fulfilled:

• 行的长度都一样吗?
• 所有字段都是有效数字吗?

这篇关于从Common Lisp中的文本文件读取数组的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！