Basti's Scratchpad on the Internet
03 Jun 2018

Syncing Org-Journal with your Calendar

A month ago, org-journal learned to deal with future journal entries. I use future journal entries for appointments or not-yet-actionable tasks that I don't want in my current TODO list just yet. This works really well while I am at my computer, and really does not work at all when I am not (Orgzly does not work with my 1k-file journal directory).

But, as I keep re-discovering, org-mode already has a solution for this: org-mode can export your agenda to an iCalendar file! Most calendar applications can then subscribe to that file, and show your future journal entries right in your calendar. And if you set it up right, this will even sync changes to your calendar!

First, you need to set up some kind of regular export job. I use a cron job that regularly runs an Emacs batch job emacs --batch --script ~/bin/calendar_init.el with the following code in calendar​_init.el:

;; no init file is loaded, so provide everything here:
(add-to-list 'load-path "~/etc/org-journal/")
(setq org-journal-dir "~/journal/"            ; where my journal files are
      org-journal-file-format ""  ; their file names
      org-journal-enable-agenda-integration t ; so entries are on the agenda
      org-icalendar-store-UID t               ; so changes sync correctly
      org-icalendar-include-todo "all"        ; include TODOs and DONEs
      org-icalendar-combined-agenda-file "~/calendar/org-journal.ics")

(require 'org-journal)
(org-journal-update-org-agenda-files) ; put future entries on the agenda
(org-icalendar-combine-agenda-files)  ; export the ICS file
(save-buffers-kill-emacs t)           ; save all modified files and exit

It is important to set org-icalendar-store-UID, as otherwise every change to a future entry would result in a duplicated calendar entry. It will clutter up your journal entries with an UID property, though.

I do this on my web server, with my journal files syncthinged from my other computers. With that, I can subscribe to the calendar file from any internet-connected computer or mobile phone (using ICSdroid). But you could just as well sync only the ICS file, or just subscribe to the local file, if you don't want to upload your complete yournal to a web server.

(Incidentally, I first implemented my own ICS export, before realizing that this functionality already existed in org-mode. It was a fun little project, and I learned a lot about org-mode's internal data structures and the weirdness that are iCalendar files.)

Tags: org-journal
25 May 2018

GDPR Compliance

Personal email is dead. The signal-to-noise ratio of my personal email account has been deeply negative for years. But the last few days have been especially riveting, with a torrent of GDPR-compliance emails from just about every company that has ever gotten their hands on my email address. Anecdotally, if spam makes up about 90% of all email traffic, and the last few days have seen a ten-fold increase in traffic due to GDPR emails, we might even have "defeated spam" for a few days! Yay internet!

But sadly, I can't add to the signal-to-noise ratio, because this website does not collect any email addresses. And even more sadly, it doesn't even collect IP addresses, or use any kind of analytics at all. Sorry about that. I honestly do not know how many people read my stuff, and I can not rank my blog posts by their popularity. And I like it that way. It prevents me from getting on any kind of treadmill to please any kind of imagined audience.

That is… with one exception: Comments on this website are powered by Disqus, and I'm sure Disqus collects all kinds of data about all kinds of things. That's why comments are now hidden behind a "Load Disqus Comments" button. I promise you that no foreign Javascript is executed unless you press that button1. And honestly, GDPR didn't even have anything to do with that. I just didn't want any foreign JavaScript.



Unless katex.min.js somehow is loading external javascript…

Tags: privacy blog
10 Apr 2018

Appending to Matlab Arrays

The variable $var appears to change size on every loop iteration. Consider preallocating for speed.

So sayeth Matlab.

Let's try it:

x_prealloc = cell(10000, 1);
x_end = {};
x_append = {};
for n=1:10000
    % variant 1: preallocate
    x_prealloc(n) = {42};
    % variant 2: end+1
    x_end(end+1) = {42};
    % variant 3: append
    x_append = [x_append {42}];

Which variant do you think is fastest?


Unsurprisingly, preallocation is indeed faster than growing an array. What is surprising is that it is faster by a constant factor of about 2 instead of scaling with the array length. Only appending by x = [x {42}] actually becomes slower for larger arrays. (The same thing happens for numerical arrays, struct arrays, and object arrays.)

TL;DR: Do not use x = [x $something], ever. Instead, use x(end+1) = $something. Preallocation is generally overrated.

Tags: matlab
07 Apr 2018

Defeating News Addiction

I want to consume the news, both because it is genuinely relevant for my work, and because conversations about news are part of my social life. But I do not want to be consumed by news, and end up scanning news websites over and over for new content, even though you know that the likelihood of finding anything interesting is small.

Over the last few months, I have tried hard to find all instances of this repeated-scanning behavior, and eliminate it. The key is to automate the scanning such that I am only ever presented with new content, but do not get hooked on the addictive variable-reward cycle of checking websites for changes over and over again.

And it all works thank to the magic of RSS:

With all this settled, I have a veritable firehose of news every day. I estimate that only 1 % of this is actually worth reading. So in the next step, I filter this list for spam. For this purpose, I use Feedbin, which aggegates all these feeds, and remembers whether I have read an article. The remaining ham I either read immediately, or forward it to Pinboard for later consumption.

With this system, I never miss anything, but once I consume all the news in my feed reader, I know I am done, and there is no point in checking and re-checking various websites over and over again.

ACHIEVEMENT UNLOCKED Defeated News Addiction!
Tags: workflow
02 Apr 2018

Scheduling Future TODOs in org-journal

I keep a simple journal in org-journal: One text file per day, in org-mode. But over the years, org-journal has grown somewhat beyond this simple use case. About three years ago, a gentleman named Vladimir Kazanov implemented a very fast text search. Thus, my journal became an information archive. About two years ago, org-journal learned to carry over TODO items to the current day if you hadn't completed them on the previous day. So it to become a to-do list. And today, org-journal gained the ability to work with future journal entries, thus becoming a calendar.

Despite all of these features however, org-journal remains one org file per day, with fancy functions to do fancy things if you want them—or ignore them, if the journal is all you need.

Back to scheduling: This work was prompted by my colleague, who organizes everything in org-mode, but is not a user of org-journal. He even eschews the use of a traditional calendar, and instead uses a few org files and the magic of org-agenda to give him a nice overview like this for the coming week[1]:

Week-agenda (W14):
Monday     2 April 2018 W14
  2018-04-02: Easter Monday 
Tuesday    3 April 2018
Wednesday  4 April 2018
Thursday   5 April 2018
  2018-04-05: Scheduled:  Give Lecture 4 on Applied Programming             :BB:
Friday     6 April 2018
  2018-04-06: Scheduled:  Release of new Eels record
Saturday   7 April 2018
Sunday     8 April 2018
  2018-04-08: Scheduled:  TODO Celebrate Sunday

And lo and behold, this now works in org-journal as well! Just create a new journal entry in the future, either by pressing i j in M-x calendar or by calling org-journal-new-scheduled-entry, and org-journal will create an entry with a SCHEDULED property of the appropriate date (prefix to suppress TODO). When the current day reaches that entry, it will incorporate it into the daily journal.

Future journal entries are highlighted in M-x calendar, and you can get an overview of them with org-journal-schedule-view, or, if you enable org-journal-enable-agenda-integration, through the ordinary org-agenda, as shown above. The agenda integration does not include past journal entries in the agenda, since agenda searches tend to become very slow if they have to traverse the hundreds of files in my journal.

[1]: This is of course not his calendar, but mine.

Tags: org-journal org-mode
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