垂直对齐浮点数在小数点上 [英] Vertical align floats on decimal dot
问题描述
(格式t〜{|〜〜16,5f |〜%〜}'(798573.467 434.543543 2.435 34443.5))
即
| 798573.44000 |
| 434.54355 |
| 2.43500 |
| 34443.50000 |
但尾随空格而不是零,如下所示:
| 798573.44 |
| 434.54355 |
| 2.435 |
| 34443.5 |
我不认为这可以轻松完成格式
的内置控制字符,但是您可以将自己的函数传递给它:
(declare(ignore colon at))
(destructuring-bind(width digits& optional(pad#空格))args
(let *((string(format nil〜v,vfwidth digits arg))
(非零(位置#\ 0 string:test#'char / = :from-end t))
(dot(position#\。string:test#'char =:from-end t))
(零( - (length string)非零(=非零点)2 1)))
(string(nsubstitute pad#\ 0 string:from-end t:count zeroes)))
(write-string string stream))) )
您可以像这样使用它:
CL-使用者> (格式t〜{|〜16,5 / my-f / |〜%〜}'(798573.467 434.543543 2.435 34443.5 10))
| 798573.44 |
| 434.54355 |
| 2.435 |
| 34443.5 |
| 10.0 |填充字符默认为#\空格
/ code>,可以像下面这样提供第三个参数:〜16,5,/ my-f /
。
使用 loop
的替代实现:
(declare(ignore colon at))
(string with string =(format nil〜v,vf(car args)(cadr args)arg)
和seen-non-zero = nil
(1-(length string))downto 0
as char =(char string i)
如果(char / = char#\0)do(setq seen-non-zero t)
collect(if(and(not seen-non-zero)
(char = char# \0)
(not(char =#\。(char string(1- i)))))
(or(caddr args)#\Space)
char)到字符
finally(write-string(nreverse(coerce chars'string))stream)))
(免责声明:也许我忽略了 format
。)
Is there a simple way to align on the decimal dot a column of floats? In other words, I would like an output like the one of (vertical bars '|' are there only for clarity purpose)
(format t "~{|~16,5f|~%~}" '(798573.467 434.543543 2.435 34443.5))
which is
| 798573.44000|
| 434.54355|
| 2.43500|
| 34443.50000|
but with trailing spaces instead of zeros, as follows:
| 798573.44 |
| 434.54355|
| 2.435 |
| 34443.5 |
I do not think that this can easily be done with format
's inbuilt control characters, but you could pass your own function to it:
(defun my-f (stream arg colon at &rest args)
(declare (ignore colon at))
(destructuring-bind (width digits &optional (pad #\Space)) args
(let* ((string (format nil "~v,vf" width digits arg))
(non-zero (position #\0 string :test #'char/= :from-end t))
(dot (position #\. string :test #'char= :from-end t))
(zeroes (- (length string) non-zero (if (= non-zero dot) 2 1)))
(string (nsubstitute pad #\0 string :from-end t :count zeroes)))
(write-string string stream))))
You can use it like this:
CL-USER> (format t "~{|~16,5/my-f/|~%~}" '(798573.467 434.543543 2.435 34443.5 10))
| 798573.44 |
| 434.54355|
| 2.435 |
| 34443.5 |
| 10.0 |
NIL
The padding character defaults to #\Space
, and may be given as a third argument like this: "~16,5,' /my-f/"
.
An alternative implementation using loop
:
(defun my-f (stream arg colon at &rest args)
(declare (ignore colon at))
(loop with string = (format nil "~v,vf" (car args) (cadr args) arg)
and seen-non-zero = nil
for i from (1- (length string)) downto 0
as char = (char string i)
if (char/= char #\0) do (setq seen-non-zero t)
collect (if (and (not seen-non-zero)
(char= char #\0)
(not (char= #\. (char string (1- i)))))
(or (caddr args) #\Space)
char) into chars
finally (write-string (nreverse (coerce chars 'string)) stream)))
(Disclaimer: Maybe I overlooked something easier in the documentation of format
.)
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