awk '{print $2,",",$1}' 在 Emacs Lisp 中？

Question

有时我会使用 AWK 来提取和/或反转数据文件中的列。

awk '{print $2,",",$1}' filename.txt

我将如何使用 Emacs Lisp 做同样的事情？

(defun awk (filename col1 &optional col2 col3 col4 col5)
  "Given a filename and at least once column, print out the column(s)
values in the order in which the columns are specified."
...
)
;; Test awk
(awk "filename.txt" 1); Only column 1
(awk "filename.txt" 2 1); Column 2 followed by column 1
(awk "filename.txt" 3 2 1); Columns 3,2 then 1

sample filename.txt :

a   b  c
1   2  5

示例输出:

b , a
2 , 1

Answer 1

你打算如何使用它？您是否打算将其用作命令行脚本？在这种情况下，您需要像这样打包它 hello world question .

或者，您是否打算以交互方式使用它，在这种情况下，您可能希望在新缓冲区中输出...

这段代码完成了基础工作。您需要更新它以匹配您的使用模型。

(defun awk (filename &rest cols)
  "Given a filename and at least once column, print out the column(s) values
in the order in which the columns are specified."
  (let* ((buf (find-file-noselect filename)))
    (with-current-buffer buf
      (while (< (point) (point-max))
        (let ((things (split-string (buffer-substring (line-beginning-position) (line-end-position))))
              (c cols)
              comma)
          (while c
            (if comma
                (print ", "))
            (print (nth (1- (car c)) things))
            (setq comma t)
            (setq c (cdr c)))
          (print "\n")
          (forward-line))))
    (kill-buffer buf)))