format - 帮助打印表格

发布于 2024-10-10 21:08:09 字数 366 浏览 6 评论 0原文

这个问题可能会以捂脸结束，但我已经尝试了一段时间，尽管阅读了超规范，但仍然卡住了。

基本上我想做的是类似的事情

(format t "~{|~{ ~5d~}|~%~}" '((1 23 2 312) (23 456 1 7890)))

，但不应该对 5 进行硬编码，而是应该从列表中计算（任何嵌套列表中最长元素的长度 + 1），以给出类似的内容，

|    1    23     2   312|
|   23   456     1  7890|

也许我在这里想得太复杂了，有一种更简单的方法可以做我想做的事，但我想我让自己陷入了无法摆脱的心理困境。

原文

This question will probably end in a facepalm, but I've tried for a while and am still stuck despite reading through the hyperspec.

Basically what I want to do is something like

(format t "~{|~{ ~5d~}|~%~}" '((1 23 2 312) (23 456 1 7890)))

but instead of hard-coding the 5 it should be calculated from the list (length of longest element from any nested list + 1) to give something like

|    1    23     2   312|
|   23   456     1  7890|

Maybe I'm thinking way too complicated here and there is an easier way to do what I want, but I think I ran myself into a mental corner that I can't get out of.

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梦里南柯 2024-10-17 21:08:11

我认为你有两个选择：让 format 魔法消失并使用其他循环结构或生成格式字符串本身：

(defun facepalm-printer (lol)
  (format t (format nil "~~{|~~{ ~~~ad~~}|~~%~~}"
                    (longest-member lol))
          lol))

longest-member 的定义留作练习给读者。

I think that you have two options: let the format magic go and use other looping constructs or generate the format string itself:

(defun facepalm-printer (lol)
  (format t (format nil "~~{|~~{ ~~~ad~~}|~~%~~}"
                    (longest-member lol))
          lol))

The definition of longest-member is left as an exercise to the reader.

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被翻牌 2024-10-17 21:08:11

~~假设需要的宽度与width绑定，那么可以这样做：~~

~~(format t "~{|~{ ~Vd~}|~%~}" width '((1 23 2 312) (23 456 1 7890)))~~

~~5已被替换为V 和 width 已作为参数添加到 FORMAT/~~

编辑：原始答案未正确解释嵌套指令

在格式控制字符串中，可以使用V来代替任何常量值，指示相应的值将从参数列表中获取。

您可以尝试以下操作：

(setf width 5)
(setf data '((1 23 2 312) (23 456 1 7890)))

(format t "~{|~{ ~{~Vd~}~}|~%~}"
  (mapcar #'(lambda (r) (mapcar #'(lambda (v) (list width v)) r)) data) )

此格式字符串要求每个值前面都有所需的宽度。 (mapcar ...) 表达式可以完成此任务。

~~Assuming the required width is bound to width, then you can do this:~~

~~(format t "~{|~{ ~Vd~}|~%~}" width '((1 23 2 312) (23 456 1 7890)))~~

~~5 has been replaced by V and width has been added as an argument to FORMAT/~~

edit: original answer did not correctly account for the nested directives

In a format control string V may be used in place of any constant value, indicating that the corresponding value is to be taken from the argument list instead.

You can try this:

(setf width 5)
(setf data '((1 23 2 312) (23 456 1 7890)))

(format t "~{|~{ ~{~Vd~}~}|~%~}"
  (mapcar #'(lambda (r) (mapcar #'(lambda (v) (list width v)) r)) data) )

This format string requires the desired width to precede each value. The (mapcar ...) expression accomplishes this.

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