41 lines
1.6 KiB
ReStructuredText
41 lines
1.6 KiB
ReStructuredText
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Rounding numbers to N decimals in Emacs
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#######################################
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:date: 2014-10-07T10:28:50Z
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:category: blog
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:tags: emacs,development
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:url: blog/2014/10/7/rounding-numbers-to-n-decimals-in-emacs.html
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:save_as: blog/2014/10/7/rounding-numbers-to-n-decimals-in-emacs.html
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:status: published
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:author: Gergely Polonkai
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I have recently faced a problem, where I had a bunch of SVG files with a large amount of fraction
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numbers in the path definitions. These images were displayed in small size, so this amount of
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precision was irrelevant, and these numbers took almost half of my SVG images’ size. So I created
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an Elisp defun to round these numbers to 2 decimals:
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.. code-block:: 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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This finds the first digit of the number under point (the cursor), and reduces its digits to the
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given amount (or the number given with :kbd:`C-u`). It has some drawbacks, though, as it cannot
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handle exponential forms (e.g. ``1e-1234``), but these were rare in my case, and its hard to
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iterate through all numbers. I will come over this latter problem soon(ish).
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