4 ms·

Can you give an example of using dc like this? Seems like something I would find really useful!

• sevensor 2y ago
  Absolutely! Suppose I'm editing a text file, and I'm working through a tradeoff between data volume and accuracy, where more accuracy requires more data. I have an array of 14 sensors, and I can configure them to take either 100-byte samples or 500-byte samples, and I can take samples at intervals between 1 and 60 seconds. So I make myself a little table: sensors size interval 14 100 1 14 100 30 14 100 60 Then I duplicate it: sensors size interval 14 100 1 14 100 30 14 100 60 14 100 1 14 100 30 14 100 60 I'm using kakoune, so I can put my cursor on the 100 in the first duplicate row, press C twice, then press r5, and now I have this table: sensors size interval 14 100 1 14 100 30 14 100 60 14 500 1 14 500 30 14 500 60 Now, I want to know bytes per day, and this is where the math comes in. I start adding columns. First I duplicate the three existing columns, since I want to see them next to the result. I can do this by putting a cursor at the beginning of each row, highlighting the whole thing, and pasting. I also hit & to line up the pasted selections. sensors size interval 14 100 1 14 100 1 14 100 30 14 100 30 14 100 60 14 100 60 14 500 1 14 500 1 14 500 30 14 500 30 14 500 60 14 500 60 Now, because I don't want to have to think about the stack too hard, I put 1440 (minutes per day) and 60 (seconds per minute) in before the interval column. sensors size interval 14 100 1 14 100 1440 60 1 14 100 30 14 100 1440 60 30 14 100 60 14 100 1440 60 60 14 500 1 14 500 1440 60 1 14 500 30 14 500 1440 60 30 14 500 60 14 500 1440 60 60 Then I add my operations. And keep in mind I'm still using multiple cursors, so all this stuff is just getting typed one time. sensors size interval 14 100 1 14 100 * 1440 * 60 * 1 / p 14 100 30 14 100 * 1440 * 60 * 30 / p 14 100 60 14 100 * 1440 * 60 * 60 / p 14 500 1 14 500 * 1440 * 60 * 1 / p 14 500 30 14 500 * 1440 * 60 * 30 / p 14 500 60 14 500 * 1440 * 60 * 60 / p Now each line has a little dc program on it, like 14 500 * 1440 * 60 * 60 / p. I then highlight the back half of each row (again, still working with the same set of cursors the whole time, it takes way longer to explain this than it does to actually do it.) I type | dc and each of my selections gets run through dc. The result is: sensors size interval 14 100 1 120960000 14 100 30 4032000 14 100 60 2016000 14 500 1 604800000 14 500 30 20160000 14 500 60 10080000 That's not super readable, so I cursor over three times (multiselection is still active!) and insert commas, and then I do it again: sensors size interval 14 100 1 120,960,000 14 100 30 4,032,000 14 100 60 2,016,000 14 500 1 604,800,000 14 500 30 20,160,000 14 500 60 10,080,000 The result is I've done a quick back-of-the-envelope calculation on how much data I need to handle in each scenario.
  • sevensor 2y ago
    Replying to my own post for a couple of follow on comments: 1. I wrote this comment using kakoune as the editor under w3m 2. I don’t know emacs as well as I’d like to. Anyone want to chime in on how you’d do this in emacs?
  • dakr 2y ago
    Thanks! This is pretty cool. I do often run shell commands on entire lines/ranges of lines in vim, but haven't tried it with just parts of lines. I just tried with vim's rectangular selection, and while it does correctly give the 'dc' output, it replaces entire lines with the output instead of just the selection. I'll have to look into this further.
    • sevensor 2y ago
      Enjoy! Kakoune’s selection-verb editing model really clicked for me; I had been a heavy user of visual mode in vim before I switched. The great Unix integration composes really well with the selection model too.