Shallow Thoughts

Akkana's Musings on Open Source Computing and Technology, Science, and Nature.

Fri, 16 Jun 2017

Flycatchers Fledging, and The Buck Stops Here

We've had a pair of ash-throated flycatchers in the nest box I set up in the yard. I've been watching them bring bugs to the nest for a couple of weeks now, but this morning they've been acting unusual: fluttering around the corner of the house near my office window, calling to each other, not spending nearly as much time near the nest. I suspect one or more of the chicks may have fledged this morning, though I have yet to see more than two flycatchers at once. They still return to the nest box occasionally (one of them just delivered a big grasshopper), so not all the chicks have fledged yet. Maybe if I'm lucky I'll get to see one fledge.

I hope they're not too affected by the smoky air. We have two fires filling the air with smoke: the Bonita Fire, 50 miles north, and as of yesterday a new fire in Jemez Springs, only about half that distance. Yesterday my eyes were burning, my allergies were flaring up, and the sky was worse than the worst days in Los Angeles in the 70s. But it looks like the firefighters have gotten a handle on both fires; today is still smoky, with a major haze down in the Pojoaque Valley and over toward Albuquerque, but the sky above is blue and the smoke plume from Jemez Springs is a lot smaller and less dark than it was yesterday. Fingers crossed!

[Buck in velvet, drinking at the pond] And just a few minutes ago, a buck with antlers in velvet wandered into our garden to take a drink at the pond. Such a nice change from San Jose!

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[ 10:40 Jun 16, 2017    More nature | permalink to this entry | comments ]

Fri, 09 Jun 2017

Emacs: Typing dashes in html mode (update for Emacs 24)

Back in 2006, I wrote an article on making a modified copy of sgml-mode.el to make it possible to use double-dashed clauses -- like this -- in HTML without messing up auto-fill mode.

That worked, but the problem is that if you use your own copy of sgml-mode.el, you miss out on any other improvements to HTML and SGML mode. There have been some good ones, like smarter rewrap of paragraphs. I had previously tried lots of ways of customizing sgml-mode without actually replacing it, but never found a way.

Now, in emacs 24.5.1, I've found a easier way that seems to work. The annoying mis-indentation comes from the function sgml-comment-indent-new-line, which sets variables comment-start, comment-start-skip and comment-end and then calls comment-indent-new-line.

All I had to do was redefine sgml-comment-indent-new-line to call comment-indent-new-line without first defining the comment characters:

(defun sgml-comment-indent-new-line (&optional soft)
  (comment-indent-new-line soft))

Finding emacs source

I wondered if it might be better to call whatever underlying indent-new-line function comment-indent-new-line calls, or maybe just to call (newline-and-indent). But how to find the code of comment-indent-new-line?

Happily, describe-function (on C-h f, or if like me you use C-h for backspace, try F-1 h) tells you exactly what file defines a function, and it even gives you a link to click on to view the source. Wonderful!

It turned out just calling (newline-and-indent) wasn't enough, because sgml-comment-indent-new-line typically calls comment-indent-new-line when you've typed a space on the end of a line, and that space gets wrapped and then messes up indentation. But you can fix that by copying just a couple of lines from the source of comment-indent-new-line:

(defun sgml-comment-indent-new-line (&optional soft)
  (save-excursion (forward-char -1) (delete-horizontal-space))
  (delete-horizontal-space)
  (newline-and-indent))

That's a little longer than the other definition, but it's cleaner since comment-indent-new-line is doing all sorts of extra work you don't need if you're not handling comments. I'm not sure that both of the delete-horizontal-space lines are needed: the documentation for delete-horizontal-space says it deletes both forward and backward. But I have to assume they had a good reason for having both: maybe the (forward-char -1) is to guard against spurious spaces already having been inserted in the next line. I'm keeping it, to be safe.

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[ 11:16 Jun 09, 2017    More linux/editors | permalink to this entry | comments ]

Mon, 05 Jun 2017

HTML Email from Mutt

I know, I know. We use mailers like mutt because we don't believe in HTML mail and prefer plaintext. Me, too.

But every now and then a situation comes up where it would be useful to send something with emphasis. Or maybe you need to highlight changes in something. For whatever reason, every now and then I wish I had a way to send HTML mail.

I struggled with that way back, never did find a way, and ended up writing a Python script, htmlmail.py to send an HTML page, including images, as email.

Sending HTML Email

But just recently I found a neat mutt hack. It turns out it's quite easy to send HTML mail.

First, edit the HTML source in your usual mutt message editor (or compose the HTML some other way, and insert the file). Note: if there's any quoted text, you'll have to put a <pre> around it, or otherwise turn it into something that will display nicely in HTML.

Write the file and exit the editor. Then, in the Compose menu, type Ctrl-T to edit the attachment type. Change the type from text/plain to text/html.

That's it! Send it, and it will arrive looking like a regular HTML email, just as if you'd used one of them newfangled gooey mail clients. (No inline images, though.)

Viewing HTML Email

Finding out how easy that was made me wonder why the other direction isn't easier. Of course, I have my mailcap set up so that mutt uses lynx automatically to view HTML email:

text/html; lynx -dump %s; nametemplate=%s.html; copiousoutput

Lynx handles things like paragraph breaks and does in okay job of showing links; but it completely drops all emphasis, like bold, italic, headers, and colors. My terminal can display all those styles just fine. I've also tried links, elinks, and w3m, but none of them seem to be able to handle any text styling. Some of them will do bold if you run them interactively, but none of them do italic or colors, and none of them will do bold with -dump, even if you tell them what terminal type you want to use. Why is that so hard?

I never did find a solution, but it's worth noting some useful sites I found along the way. Like tips for testing bold, italics etc. in a terminal:, and for testing whether the terminal supports italics, which gave me these useful shell functions:

echo -e "\e[1mbold\e[0m"
echo -e "\e[3mitalic\e[0m"
echo -e "\e[4munderline\e[0m"
echo -e "\e[9mstrikethrough\e[0m"
echo -e "\e[31mHello World\e[0m"
echo -e "\x1B[31mHello World\e[0m"

ansi()          { echo -e "\e[${1}m${*:2}\e[0m"; }
bold()          { ansi 1 "$@"; }
italic()        { ansi 3 "$@"; }
underline()     { ansi 4 "$@"; }
strikethrough() { ansi 9 "$@"; }
red()           { ansi 31 "$@"; }

And in testing, I found that a lot of fonts didn't offer italics. One that does is Terminus, so if your normal font doesn't, you can run a terminal with Terminus: xterm -fn '-*-terminus-bold-*-*-*-20-*-*-*-*-*-*-*'

Not that it matters since none of the text-mode browsers offer italic anyway. But maybe you'll find some other use for italic in a terminal.

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[ 18:28 Jun 05, 2017    More linux | permalink to this entry | comments ]

Wed, 31 May 2017

Tiger Salamander Larvae

[Tiger salamander with gills] [Tiger salamander with gills] I got a tip that there were tiger salamanders with gills swimming around below Los Alamos reservoir, so I had to go see for myself.

They're fabulous! Four to five inch salamanders with flattened tails and huge frilly gills behind their heads -- dozens of them, so many the pond is thick with them. Plenty of them are hanging out in the shallows or just below the surface of the water, obligingly posing for photos.

I had stupidly brought only the pocket camera, not the DSLR -- and then the camera's battery turned out to be low -- so I was sparing with camera, but even so I was pleased at how well they came out, with the camera mostly managing to focus on the salamanders rather than (as I had feared) the surface of the murky water. I may go back soon with the DSLR. It's an easy, pleasant hike.

Photos: Tiger Salamander larvae.

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[ 20:31 May 31, 2017    More nature | permalink to this entry | comments ]

Tue, 23 May 2017

Python help from the shell -- greppable and saveable

I'm working on a project involving PyQt5 (on which, more later). One of the problems is that there's not much online documentation, and it's hard to find out details like what signals (events) each widget offers.

Like most Python packages, there is inline help in the source, which means that in the Python console you can say something like

>>> from PyQt5.QtWebEngineWidgets import QWebEngineView
>>> help(QWebEngineView)
The problem is that it's ordered alphabetically; if you want a list of signals, you need to read through all the objects and methods the class offers to look for a few one-liners that include "unbound PYQT_SIGNAL".

If only there was a way to take help(CLASSNAME) and pipe it through grep!

A web search revealed that plenty of other people have wished for this, but I didn't see any solutions. But when I tried running python -c "help(list)" it worked fine -- help isn't dependent on the console.

That means that you should be able to do something like

python -c "from sys import exit; help(exit)"

Sure enough, that worked too.

From there it was only a matter of setting up a zsh function to save on complicated typing. I set up separate aliases for python2, python3 and whatever the default python is. You can get help on builtins (pythonhelp list) or on objects in modules (pythonhelp sys.exit). The zsh suffixes :r (remove extension) and :e (extension) came in handy for separating the module name, before the last dot, and the class name, after the dot.

#############################################################
# Python help functions. Get help on a Python class in a
# format that can be piped through grep, redirected to a file, etc.
# Usage: pythonhelp [module.]class [module.]class ...
pythonXhelp() {
    python=$1
    shift
    for f in $*; do
        if [[ $f =~ '.*\..*' ]]; then
            module=$f:r
            obj=$f:e
            s="from ${module} import ${obj}; help($obj)"
        else
            module=''
            obj=$f
            s="help($obj)"
        fi
        $python -c $s
    done
}
alias pythonhelp="pythonXhelp python"
alias python2help="pythonXhelp python2"
alias python3help="pythonXhelp python3"

So now I can type

python3help PyQt5.QtWebEngineWidgets.QWebEngineView | grep PYQT_SIGNAL
and get that list of signals I wanted.

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[ 14:12 May 23, 2017    More programming | permalink to this entry | comments ]

Thu, 18 May 2017

Pot Sherd

Wandering the yard chasing invasive weeds, Dave noticed an area that had been disturbed recently by some animal -- probably a deer, but there were no clear prints so we couldn't be sure.

But among the churned soil, he noticed something that looked different from the other rocks.

[Pot sherd we found in the yard] A pot sherd, with quite a nice pattern on it!

(I'm informed that fragments of ancient pots are properly called "sherds"; a "shard" is a fragment of anything other than a pot.)

Our sherd fairly large as such things go: the longest dimension is about two inches.

Of course, we wanted to know how old it was, and whether it was "real". We've done a lot of "archaeology" in our yard since we moved in, digging up artifacts ranging from bits of 1970s ceramic and plastic dinnerware to old tent pegs to hundreds of feet of old rotting irrigation tubing and black plastic sheeting. We even found a small fragment of obsidian that looked like it had been worked (and had clearly been brought here: we're on basalt, with the nearest obsidian source at least fifteen miles away). We've also eyed some of the rock rings and other formations in the yard with some suspicion, though there's no way to prove how long ago rocks were moved. But we never thought we'd find anything older than the 1970s when the house was built, or possibly the 1940s when White Rock was a construction camp for the young Los Alamos lab.

So we asked a friend who's an expert in such matters. She tells us it's a Santa Fe black-on-white, probably dated somewhere between 1200-1300 AD. Santa Fe black-on-white comes in many different designs, and is apparently the most common type of pottery found in the Los Alamos/Santa Fe area. We're not disappointed by that; we're excited to find that our pot sherd is "real", and that we could find something that old in the yard of a house that's been occupied since 1975.

It's not entirely a surprise that the area was used 700 years ago, or even earlier. We live in a community called La Senda, meaning "The Path". A longtime resident told us the name came from a traditional route that used to wind down Pajarito Canyon to the site of the current Red Dot trail, which descends to the Rio Grande passing many ancient petroglyphs along the way. So perhaps we live on a path that was commonly used when migrating between the farmland along the Rio and the cliff houses higher up in the canyons.

What fun! Of course we'll be keeping our eyes open for more sherds and other artifacts.

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[ 20:16 May 18, 2017    More misc | permalink to this entry | comments ]

Fri, 05 May 2017

Moon Talk at PEEC tonight

Late notice, but Dave and I are giving a talk on the moon tonight at PEEC. It's called Moonlight Sonata, and starts at 7pm. Admission: $6/adult, $4/child (we both prefer giving free talks, but PEEC likes to charge for their Friday planetarium shows, and it all goes to support PEEC, a good cause).

We'll bring a small telescope in case anyone wants to do any actual lunar observing outside afterward, though usually planetarium audiences don't seem very interested in that.

If you're local but can't make it this time, don't worry; the moon isn't a one-time event, so I'm sure we'll give the moon show again at some point.

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[ 15:26 May 05, 2017    More speaking | permalink to this entry | comments ]

Tue, 25 Apr 2017

Typing Greek letters

I'm taking a MOOC that includes equations involving Greek letters like epsilon. I'm taking notes online, in Emacs, using the iimage mode tricks for taking MOOC class notes in emacs that I worked out a few years back.

Iimage mode works fine for taking screenshots of the blackboard in the videos, but sometimes I'd prefer to just put the equations inline in my file. At first I was typing out things like E = epsilon * sigma * T^4 but that's silly, and of course the professor isn't spelling out the Greek letters like that when he writes the equations on the blackboard. There's got to be a way to type Greek letters on this US keyboard.

I know how to type things like accented characters using the "Multi key" or "Compose key". In /etc/default/keyboard I have XKBOPTIONS="ctrl:nocaps,compose:menu,terminate:ctrl_alt_bksp" which, among other things, sets the compose key to be my "Menu" key, which I never used otherwise. And there's a file, /usr/share/X11/locale/en_US.UTF-8/Compose, that includes all the built-in compose key sequences. I have a shell function in my .zshrc,

composekey() {
  grep -i $1 /usr/share/X11/locale/en_US.UTF-8/Compose
}
so I can type something like composekey epsilon and find out how to type specific codes. But that didn't work so well for Greek letters. It turns out this is how you type them:
<dead_greek> <A>            : "Α"   U0391    # GREEK CAPITAL LETTER ALPHA
<dead_greek> <a>            : "α"   U03B1    # GREEK SMALL LETTER ALPHA
<dead_greek> <B>            : "Β"   U0392    # GREEK CAPITAL LETTER BETA
<dead_greek> <b>            : "β"   U03B2    # GREEK SMALL LETTER BETA
<dead_greek> <D>            : "Δ"   U0394    # GREEK CAPITAL LETTER DELTA
<dead_greek> <d>            : "δ"   U03B4    # GREEK SMALL LETTER DELTA
<dead_greek> <E>            : "Ε"   U0395    # GREEK CAPITAL LETTER EPSILON
<dead_greek> <e>            : "ε"   U03B5    # GREEK SMALL LETTER EPSILON
... and so forth. And this <dead_greek> key isn't actually defined in most US/English keyboard layouts: you can check whether it's defined for you with: xmodmap -pke | grep dead_greek

Of course you can use xmodmap to define a key to be <dead_greek>. I stared at my keyboard for a bit, and decided that, considering how seldom I actually need to type Greek characters, I didn't see the point of losing a key for that purpose (though if you want to, here's a thread on how to map <dead_greek> with xmodmap).

I decided it would make much more sense to map it to the compose key with a prefix, like 'g', that I don't need otherwise. I can do that in ~/.XCompose like this:

<Multi_key> <g> <A>            : "Α"   U0391    # GREEK CAPITAL LETTER ALPHA
<Multi_key> <g> <a>            : "α"   U03B1    # GREEK SMALL LETTER ALPHA
<Multi_key> <g> <B>            : "Β"   U0392    # GREEK CAPITAL LETTER BETA
<Multi_key> <g> <b>            : "β"   U03B2    # GREEK SMALL LETTER BETA
<Multi_key> <g> <D>            : "Δ"   U0394    # GREEK CAPITAL LETTER DELTA
<Multi_key> <g> <d>            : "δ"   U03B4    # GREEK SMALL LETTER DELTA
<Multi_key> <g> <E>            : "Ε"   U0395    # GREEK CAPITAL LETTER EPSILON
<Multi_key> <g> <e>            : "ε"   U03B5    # GREEK SMALL LETTER EPSILON
... and so forth.

And now I can type [MENU] g e and a lovely ε appears, at least in any app that supports Greek fonts, which is most of them nowadays.

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[ 12:57 Apr 25, 2017    More linux | permalink to this entry | comments ]