44 lines
1.5 KiB
Markdown
44 lines
1.5 KiB
Markdown
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---
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layout: post
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title: "Rounding numbers to N decimals in Emacs"
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date: 2014-10-07 10:28:50+00:00
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tags: [emacs, development]
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permalink: /blog/2014/10/7/rounding-numbers-to-n-decimals-in-emacs
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published: true
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author:
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name: Gergely Polonkai
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email: gergely@polonkai.eu
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---
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I have recently faced a problem, where I had a bunch of SVG files with a
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large amount of fraction numbers in the path definitions. These images were
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displayed in small size, so this amount of precision was irrelevant, and
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these numbers took almost half of my SVG images’ size. So I created an
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Elisp defun to round these numbers to 2 decimals:
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{% highlight common-lisp %}
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(defun get-number-at-point ()
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(interactive)
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(skip-chars-backward "0123456789.-")
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(or (looking-at "[0123456789.-]+")
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(error "No number at point"))
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(string-to-number (match-string 0)))
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(defun round-number-at-point-to-decimals (decimal-count)
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(interactive "NDecimal count: ")
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(let ((mult (expt 10 decimal-count)))
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(replace-match (number-to-string
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(/
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(fround
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(*
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mult
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(get-number-at-point)))
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mult)))))
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{% endhighlight %}
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This finds the first digit of the number under point (the cursor), and
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reduces its digits to the given amount (or the number given with `C-u`). It
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has some drawbacks, though, as it cannot handle exponential forms (e.g.
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`1e-1234`), but these were rare in my case, and its hard to iterate through
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all numbers. I will come over this latter problem soon(ish).
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