All posts by Neil

Geeking out even more with Pythagoras and Lego triangles

In case my previous musings on lego triangles weren’t geeky enough for you, here’s some more.

60 degree 3-7-8 / 5-7-8 math

In my prior note I pointed out that you could construct an exact 60 degree angle with a 3-7-8 or 5-7-8 construction, such as this one:


The blue technic beam is the “7” unit leg. Building this within an 8-8-8 equilateral triangle helps convince us that the angle opposite the 7 unit beam is a 60 degree angle.

In the prior post I wrote “This construction is probably demonstrating some deep mathematical relationship between the 3-7-8 60 degree construction and the 5-7-8 construction; perhaps someone will point it out to me and I’ll add it back into this note.”

Well I’ve worked it out for myself.

Review: Trigonometry says that if we know sides a, b, and c and we want to know the angle B opposite side b, we can start with the law of cosines:

b^2 = a^2 + c^2 – 2*a*c * cos B

In the case where angle B is 60 degrees, cosine(60) is exactly 1/2, so this formula becomes:

b^2 = a^2 + c^2 – a*c

Now we can see why (a,b,c) = (3,7,8) forms a 60 degree angle opposite the 7 side:

7^2 = 3^2 + 8^2 – (3*8)
49 = 9 + 64 – 24

The numbers work; (3,7,8) is consistent with that equation and therefore the angle opposite the b side is a 60 degree angle.

It follows from this that if (a, b, c) is a solution then (c – a, b, c) is also a solution. To see this, work the substitution of c-a for a through the equation.

Thus once we know (3,7,8) has the 60 degree angle in it we could find (x, 7, 8) where:

x = c – a
x = 8 – 3

which gets us the (5, 7, 8) solution.

Some other integer solution pairs to this are:

  • (5, 19, 21) and (16, 19, 21)
  • (7, 13, 15) and (8, 13, 15)
  • (11, 31, 35) and (24, 31, 35)

That last pair is huge but might be useful if divided in two using half-unit construction.

I built a nice looking 5,7,8 connection inside a 9-9-9 equilataral, all built using system bricks just as a demo.

5-7-8 inside equilateral; top view
5-7-8 inside equilateral; top view
5-7-8 inside equilateral; bottom view
5-7-8 inside equilateral; bottom view

I had to use “pylons” (visible in the bottom view) to make this work because, as usually happens with the system brick triangle constructions, the adjacent studs will interfere unless you build up using a pylon/riser construction.

Other Fractional Construction Techniques

Lego CAD tools that make use of the LDraw system define brick geometry in units called LDU (an “LDraw Unit” I suppose). A standard system brick is 24 LDU high and the stud-to-stud (or hole-to-hole in technic) spacing is 20LDU. So far we have been talking about constructions using an integer number of holes (20LDU) or half-holes (10LDU).

Because of the 24:20 (6:5) ratio of stud-spacing vs brick height, turning bricks on their side gives offsets other than just integers and halves. Bricks on their sides is called SNOT: “Studs Not On Top”

This allows resolution down to 4LDU for offsets, corresponding to 0.2 of the stud-to-stud distance. By using system bricks (with technic holes as required) we open up many more angle possibilities, including some new Pythagorean triples such as:

(6.6, 11.2, 13)

Of course, that triple was already “available” as an integer construction, with the original Pythagorean triple being an enormous (33,56,65). It could be reduced to (16.5, 28, 32.5) using half-unit construction, but the SNOT techniques allow us to realize that particular construction this way:


It may be easier to see this in an LDraw:


I left the pins out of this rendering just for clarity so you could see all the holes.

Look at the vertical element in more detail:


This shows the general technique for achieving fractional distance at 0.2 resolutions. Every “system” brick laid on its side adds 24 LDU (or 1.2 “holes”) to the distance. As with the technic beams you have to be mindful of the +1 factor because what matters is the center-to-center distance. So it takes a stack of four system bricks on their side to add a total of three times the height of a single system brick. The net of this construction is that the vertical segment is 6.6 units in length. The math for the other part of the construction works similarly.

Recap: Complete Pythagorean Triangle List

Taking all these techniques together, here is the complete list of Pythagorean Triangles you can make with the maximum dimension being less than 25 (there are more above that point), and the angle you get for the hypotenuse. The table is sorted by angle A, the smaller angle of the two non-right angles (the other angle is always 90 – A).

Table without using any SNOT techniques:

 4.5   20 20.5   12.680
   7   24   25   16.260
   6 17.5 18.5   18.925
   5   12   13   22.620
   8   15   17   28.072
   3    4    5   36.870
  10 10.5 14.5   43.603

Table including SNOT triangles:

 2.6 16.8   17    8.797
 4.5   20 20.5   12.680
 3.2 12.6   13   14.250
   7   24   25   16.260   
    ... SNOT version: 2.8, 9.6, 10
   6 17.5 18.5   18.925
 8.8 23.4   25   20.610
   5   12   13   22.620
 7.2 15.4   17   25.058
   8   15   17   28.072
 6.6 11.2   13   30.510
   3    4    5   36.870
  10 10.5 14.5   43.603

Of course you can scale entries in the table. So, for example. you could make the SNOT version of (7,24,25) at (5.6, 19.2, 20) though at that point you probably might as well make it using the integer (7,24,25) construction.

New versions of API libraries

Released new versions of both the Python and Ruby interfaces to the Numerous APIs. This update allows you to call write() with the “only write it if the value changed” feature and just ignore any exception that comes (when the value hasn’t changed). This is probably a more common usage pattern. So now, for example, you can do this in python:

m.write(newvalue, onlyIf="IGNORE")

where before you would have had to write:

    m.write(newvalue, onlyIf=True)
except NumerousMetricConflictError:

to handle the reported “no change” exception even when you didn’t care about it. Specifying onlyIf as True gives you this older behavior and specifying the string ‘IGNORE’ (must be UPPER CASE) gives the newer behavior.

The ruby library has the same enhancement.

As a reminder of typical installation methods:

% sudo pip install numerous

You may need to do “pip2” or “pip3” instead, depending on your specific environment and which flavor of python you are installing. Also if you are upgrading from an already installed version:

% sudo pip install –upgrade numerous

Similarly you install the ruby gem via “sudo gem install numerousapp” (note slight name difference here).

Github sources:

Documentation for either library can be found on its wiki page (accessible from the github home page links given above).

Arduino JSON Web Server

I wrote a small program to implement a web server with a JSON/HTTP interface for accessing I/O pins on the Arduino.

Of course to use this you have to have an Ethernet shield (wired or WiFi) on your Arduino; a standard bare Arduino by itself has no network interface. But if you have the shield, then this software gives you a network-ready interface to the analog and digital I/O capabilities of the board.

You can, for example, do a GET on /v1/analogRead/5 to read pin 5 from your Arduino, or POST a JSON object to /v1/digitalWrite to set a pin HIGH or LOW, etc. See the README file at for details and source code.

Arduino and Numerous, with help from IFTTT

Here’s one way to connect an Arduino to a Numerous metric.

The best solution would be to port the Numerous API to the Arduino; however, there is a footprint problem especially with SSL: there is only 2K of RAM on a standard Arduino. I could not find any Arduino ports of SSL (which is required by Numerous).

Maybe Numerous needs to provide a port 80 (non-SSL) interface, though that risks exposing your API key “to the world” in transit. In the meantime, that leaves two alternatives:

  1. Use another computer, local to the Arduino, as a bridge.
  2. Send data directly from the Arduino to Numerous another way.

Option 1 is what I’ve been doing up until now. You write Arduino code to send data out the USB port and write “bridge” code on a small Linux box (e.g., a Raspberry Pi). The Linux code reads the USB data and processes it further (e.g., sends it to NumerousApp). A variation of this can be done with a tiny web server (or other TCP server) on an Arduino instead using USB (I’ve done that too).

With IFTTT integration we can go the option 2 route and eliminate the Linux box, at the cost of giving up some security (more on this later).

You will need:

  • An IFTTT account (free).
  • Connect the Maker channel to your IFTTT account (free).
  • An Ethernet shield (wired or WiFi) on your Arduino.

Go sign up for IFTTT if you haven’t already, and connect the Maker channel.

When you connect the Maker channel you will see a page that looks like this:


You need the key as shown; this will go into your Arduino code in a moment.

[ No, of course that’s not my real key shown above ]

Next you need to create an event that will be triggered from the Arduino. Go back to your home IFTTT page and create a new recipe, using the Maker channel as the IF part. Give your event a name, in this case I used “arduino_example”


When you press Create Trigger you’ll be taken to the “THAT” part of the recipe. Find the Numerous channel and select it (you will have to “connect” it if this is your first time), then for this example choose “Update a Number”:


You will next see a screen where you can select one of your Numerous metrics to be updated, and select what value to update it with. You want to use an “ingredient” (click on the beaker/test-tube thing) and you should select one of the Value fields like “value1”. Whatever you select here is what you will code into your Arduino code; as you can see you can return up to three different values to use with one single event.


That’s it … now to write some Arduino code to generate this event.

You need to know the secret key you were given when you connected the Maker channel, the name of the event you created (“arduino_example” in this case), and which of the values you decided to connect to the metric (“Value1” in this case). Then “all” you need to do is generate a simple POST request from your Arduino in the appropriate format.  That format can be found from (you can also recover your key from there). Click on “How to Trigger events” and it will show you the request format you need to generate.

I’ve written some example Arduino code to do this and made it available as a Gist:

As you can see from that code, the format of the URL that you POST to is:


With the server being at “” (port 80 for standard HTTP)

You POST a JSON object that looks like this:

{ "value1" : "123", 
  "value2" : "456", 
  "value3" : "values can be strings too" }

As you can see from the code itself, squeezing this into the primitives available in the Arduino environment isn’t always pretty; you especially need to be very careful about using up too much memory for “programming niceness”. But the code shows you one way to construct the POST, with the minimal set of HTTP headers that will work, and some example values. You can put this into your own Arduino application and modify it as necessary.

A few tricky points worth noting:

  • I don’t know how often you can generate an IFTTT/Maker event without triggering some kind of limit. In this code I limited the updates to once every five minutes.
  • Don’t forget that all-important “L” on your delay() constants if they are “large” (larger then 32000 milliseconds). Arduino is a 16 bit machine and you won’t get the result you want if you say delay(300*1000) with no “L” on the constant.
  • All those string literals use up RAM. You probably already understand this (or will soon) if you are an Arduino programmer. You might want to look up PROGMEM and ways of getting those literals into flash (program) memory instead of RAM.

About security: we’ve bypassed SSL on the path from the Arduino to IFTTT. The path between IFTTT/Maker and our Numerous account is still secure (via SSL) but the POST request that we are transmitting to IFTTT is plain text and potentially viewable “in transit” if you are inclined to worry about such things. This means your IFTTT/Maker key will be visible to anyone who has access to the intermediate routers. If this matters to you, you will need to go back to Option 1 (local bridge/Linux machine and secure connection to the outside world). On the other hand, if all you are doing is exporting the current temperature of your fridge to a Numerous metric, it’s not clear you need to worry so much about this. You should also keep in mind that the IFTTT key doesn’t really let anyone “do” anything other than post bogus events to your trigger. If you are worried that someone would do that to confuse you about your refrigerator temperature, then you need to go back to the “option 1” architecture which uses SSL to communicate to the outside world. But for a lot of applications this will be a handy way to easily connect an Arduino to Numerous (or anything else IFTTT can connect to).

Lego Technic Triangle Geometry

Time for some fun with Pythagoras!

Lego tends towards rectangular constructs, but sometimes we might want to make triangular connections. Technic beams especially lend themselves to this.

Right-angled pythagorean triangles are fairly easy to construct. Here’s a 3,4,5 triangle:


Notice that when you build it you build it as 4,5,6. That’s because it’s the distance between the pin centers that has to be in the 3-4-5 ratio. Two pins separated by 2 holes are a total distance (center-to-center) of three holes apart. Or said another way, two pins right next to each other are distance “one unit” apart, not two. Thus: A two-hole beam would be a distance of “one unit” in this analysis.

There are many pythagorean integer triangles. Here’s the complete list up to a reasonable size:

  • 3-4-5 (also 6-8-10, 9-12-15, 12-16-20 etc)
  • 5-12-13
  • 7-24-25
  • 8-15-17

If you try to build these don’t forget the +1 factor for counting holes.

If we allow half unit offsets there are some more pythagorean triangles available. Obviously any of the above constructs can be divided in two; beyond those we also have:

  • 4.5-20-20.5
  • 6-17.5-18.5
  • 7.5-18-19.5
  • 10-10.5-14.5
  • 12-22.5-25.5
  • 13.5-18-22.5

In the 3-4-5 family the angle opposite the “4” side is 53.13 degrees. The reason this is good to know is that the standard bent beams are at that same angle (53.130) and now you know why:


If you build this you will see that the angles match up perfectly.

If you combine a pythagorean triangle with its mirror you will get an isosceles triangle. Here, for example, is a 6-5-5 construction which is two mirrored 3-4-5 triangles


Notice, once again, you build 6-5-5 as 7-6-6 if you are counting the total number of holes in each side. This kind of construction will be very strong and also has the advantage of being able to attach things to the vertical riser in the spine of the triangle and have them be “on grid” whereas the holes in the angled beams are rarely ever “on grid” except at the vertices.

Trapezoid Extension – Pythagorean

Once you can make a triangle, you can make a corresponding trapezoid by extending it evenly in one dimension. This is easy to do for right (pythagorean) triangles:


Here I took a 3-4-5 triangle and extended out the base (by 4 in this case; “n” as shown in the diagram). I have to extend the connection point up top out the same amount. The geometry still works and everything lines up.

We’ll revisit this topic for non-pythagorean triangles in a moment; there are some triangles that you can extend into trapezoids and some that you can’t (easily).

System Brick Triangles

You can make triangles using system (“standard lego”) bricks too:


Note how I used two 1×1 bricks to create “pylons” for the angled brick. You have to do this, or something similar, because the neighboring studs will interfere with the angled piece.

General Triangles

Any three beams that satisfy the triangle inequality can be formed into a triangle. In general you will need to use four beams in the construction because you need to “jump” up/down one level to make the last connection work. Look at the construction of the 3-4-5 pythagorean triangle to see an example of why 4 beams are needed (and in that case since one of the joints is a 90 degree angle I used a T piece but in general you will want to use just straight beams when making angles that are not 90 degrees).

The lengths of the triangle sides will determine the angles according to standard triangle side-side-side (SSS) solutions. Just hook them together and let the angles fall where they may.

Of course, we might like to know what those angles actually are. I wrote a small python program that calculates Lego triangle angle information for a given configuration of sides. The source is available here:

If you prefer, here is the table of output it generates for full-unit constructions and half-units:

You can use the command line options (read the source) or just peruse the uploaded table and see that there are some other useful angles you can construct, though in some cases you will have to settle for close approximations. For example, there is no 45 degree construction but there are two that come close:

  • 5-12-15 will generate an angle of 45.036 degrees.
  • 13-17-17 generates 44.959

Any equilateral construction generates 60 degrees but so do these:

  • 3-7-8
  • 5-7-8

Here’s a 3-7-8 construction. The angle between the blue and red beams is 60 degrees.


This construction also more clearly illustrates the need to use four beams (not just three) to make a triangle because of how the “levels” at the vertices work out. One of the sides has to jump back down in order to join with the remaining side.

Because of that 60 degree angle, that implies you can build a 3-7-8 connection across an 8-8-8 equilateral triangle:


The angles opposite the blue beam (both above it and below it) are both 60 degree angles (by definition because the outer frame is an equilateral triangle). This construction is probably demonstrating some deep mathematical relationship between the 3-7-8 60 degree construction and the 5-7-8 construction; perhaps someone will point it out to me and I’ll add it back into this note.

If you have a larger equilateral triangle you can still make this connection at this point near the vertices or of course you could scale up the 3-7-8 or 5-7-8 as appropriate (possibly using half unit constructions too if necessary).

Don’t forget (in case you are confused again): building something with a 3-7-8 relationship takes hole counts of 4-8-9. You can count the holes in the above picture and verify this.

Non-pythagorean Trapezoids

Let’s look at a 4-8-10 triangle (which would be equivalent to a 2-4-5 triangle but this is easier to construct):


As always: built as 5-9-11.

The angles on this triangle are 22.332 (between blue and yellow), 49.458 (between blue and red), and 108.21 (between red and yellow).

Let’s say we want to make a trapezoid out of this. We can, for example, extend the blue beam to the right by making it longer, and finish out the rest of the trapezoid with right angles:


but, as you can see, we have a problem with the final joint at the red/yellow (and pink) vertex. That point isn’t on grid, whereas the pink beam, the black “riser” L piece, as well as the blue base are all on grid.

We can calculate the location of the red/yellow vertex using standard trigonmetry. Using the yellow/blue vertex as the origin, the X and Y coordinates (X along the blue beam) of the end of the yellow beam will be:

X = 8 * cos(22.332°) = 7.4

Y = 8 * sin(22.332°) = 3.04

NOTE: It’s “8” because that’s the length of the yellow side of the triangle.

The vertex doesn’t even line up vertically even though it looks like it might. It’s just close. It definitely doesn’t line up horizontally. We have no way to make that final connection.

Generally speaking you can’t easily extend non-pythagorean triangles into grid-legal trapezoid constructions.

A few constructions come very close; whether you want to use them in your models is up to you. They aren’t “on grid” but any given construction always has a certain amount of play in it and if they are close enough then things will appear to work. I believe the Lego corporation would refuse to accept these constructions as part of a design for a set, so in that sense they are “illegal”.

Here’s one that comes very close. Take the 3-7-8 triangle we saw before:


Taking the blue base as the X axis and the blue-red vertex as the origin, we can calculate the location of the red-yellow vertex. We already know that the angle between the red and blue is 60 degrees (you can reverify this using my tables or perform your own SSS triangle solution for 3-7-8; the angle opposite the 7 side is 60 degrees). Since the red leg is 8 units in length the location of the red-yellow vertex is:

X = 8 * cos(60°) = 4.00

Y = 8 * sin(60°) = 6.93


The X coordinate works out evenly on-grid, thanks to the cosine of 60 degrees being exactly one half. The Y coordinate is off grid but close enough that the following construction will appear to work:


In reality the pink beam is at (relative) height 6.93 on its left end and 7.00 on its right, thus there is some stress/flexing in the construction to make it work. You might reduce that stress slightly by only pinning the pink beam with one pin at the right end (vs the two shown in this build).

This just happens to work out as a case where the off-grid amount is smaller than the inherent flex in the pieces. Your mileage may vary; personally I don’t use these non-aligned constructions in my models but I present this as being one that is very close to ok. You can find others generally by doing math or by just trying things to see what works within reason.

Going back to the 4-8-10 (5-9-11) construction, there is a way to make a trapezoid out of it, like this:


because what I did here is just extend the base, then insert a parallel corresponding extension (the black beam), and connect them with a beam (the second red beam) that is parallel to the original side of the triangle. This preserves all the geometry and gets everything lined up in the right spot; however, in this entire construction only the blue beam is “on grid”; everything else is at non-standard locations.

This structure is quite stable and reasonably strong though I’d be cautious about putting too much weight or pressure on it from top (perhaps someone will work out the statics on this one; just going by feel it seems reasonably strong but I’m not sure exactly where the forces are going when it is put into compression that way).

Approximate “standard” angles

I already listed two constructions that are very close to a 45 degree angle; here is a more complete list of approximations to common/useful angles.

30 degrees (approximate)

a b c ∠° Error Comments
3 5 6 ∠A = 29.9264  0.0736°  should prefer 4 7 8 usually
4 7 8 ∠A = 29.9947  0.0053° closest / smallest
7 12 14 ∠A = 29.9947  0.0053° same angle as 4-7-8; larger

Of course multiples of those triples works, so for example 8-14-16 is another good 30 degree approximation (doubled from 4-7-8).

Half-unit constructions can get even closer:

a b c ∠° Error Comments
5.5 9.5 11 ∠A = 29.9996  0.0004°
5.5 14.5 19 ∠B = 29.9996  0.0004° same angle as 5.5-9.5-11 which is easier to build.
7.5 13 15 ∠A = 29.99997  0.00003° nearly “exact” for all practical purposes.

The 7.5-13-15 triple can be looked at as half of a 15-15-15 equilateral triangle. A point 7.5 along one leg is halfway; if we then went exactly 90 degrees up to the other vertex we should have a height of:

  h = 15 * sin(pi/3)                     # (pi/3 = 60 degrees in radians)

which computes out to h = 12.9904. So our actual height of 13 won’t form a true half of a true equilateral triangle; it will resolve to angles that are slightly off in all spots, but based on how close 13 is to 12.99 you can see why building the triangle at 7.5-13-15 gets so close to the 30 degrees.

If you really need an exact 30 degrees you can get it from the complementary angle on an equilateral construction or from any of the other exact 60 degree constructions (see table lower down).

45 degrees (approximate)

There aren’t any 45 degree approximations that are as close as the 30 degree ones unless we allow half unit constructions. Here is the table of some useful ones including half-units:

a b c ∠° Error Comments
3 19 21 ∠B = 45.06135 0.061°
5 12 15 ∠B = 45.03565 0.036° best/smallest integer construction.
6 12.5 16 ∠B = 45.00612 0.006° very good; see 8-8.5-12.
8 8.5 12 ∠B = 45.00612 0.006° Same ∠ as 6-12.5-16 but smaller. Second best known.
9.5 14 19 ∠B = 45.00349 0.0035° Best (but uses half-units).
11 18 24 ∠B = 45.05405 0.054° 5-12-15 is a better integer construct.

60 degrees

You can, of course, easily get 60 degrees from any equilateral triangle construction (all sides equal). You can also get it from the complementary angle on any of the above 30 degree constructions.

There are quite a few triples that lead to exact 60 degree angles. Here are a few of the simpler and more likely useful ones (including half units):

a b c Comments
1.5 3.5 4
2.5 3.5 4
2.5 9.5 10.5
3 7 8 Just double 1.5-3.5-4
4 6.5 7.5
5 7 8 Just double 2.5-3.5-4

NOTE: In all of these, it is angle B that is the 60 degree (exact) angle.

41.4096 degrees

Say what? Well, the cosine of 41.4096 is 0.75, which means that a beam on this angle will generate a half-unit offset at two holes and every four holes thereafter.

Is this useful? I’m not sure. There is a problem that the sine (0.6614) is nothing useful, so this means that while your beam will have holes at half-unit offsets in one dimension, the other dimension will never be on-grid. Nevertheless, for your amusement, I present this table:

a b c cosine Comments
2 2 3 cos(∠A) = 0.75 exact Isoceles; angle B also works.
3 8 10 cos(∠B) = 0.75 exact Note this one is angle B
4 5 6 cos(∠A) = 0.75 exact

Here’s an example 2-2-3 construction, with the orange lines showing which holes (in the blue beam) are on half-unit offsets from the adjacent beam. Any appearance of not being in alignment is an artifact of the 3D rendering; the math works. However, as already pointed out, the holes are definitely off-grid in the other dimension so I’m not sure how this sort of construction might be useful. I present it anyway just as food for thought.



If for some unusual reason you needed to get a very specific offset, you could use this cosine concept to figure out what angle you’d need to get you there. Let’s say you need an 0.6 offset and you’ve decided (usually for construction reasons) you want to go three units along the hypotenuse to get there. You need an angle that has a cosine of 0.2, which, after you’ve gone three units along the angled beam will have moved you 0.6 on the rectilinear grid.  You find the angle using arccos; that angle would be 78.463 and you could build it using (per the table or the program) 5-6-7.

Admittedly, it’s going to be a very unusual set of circumstances that makes you want special offsets — probably involving integrating with other non-Lego parts, or desparately trying to make a non-standard trapezoidal construction work out. Regardless, you’ll still have the problem of the other dimension which just won’t be where you want it anyway. In reality you’ll probably just use an axle and one piece slid along the axle (thus taking on a non-grid position) to get there; thus all this math is probably a waste of space.  But maybe it will inspire someone to do something particularly clever one day.

53.130 degrees

We already saw that this angle (more precisely it is 53.130102) appears in the 3-4-5 family of pythagorean triangles and is the angle of one of the standard lego “bent” beams.

Are there any other triples that generate this angle? Yes, there are. First of all, any isoceles triangle constructed using a mirrored pythagorean 3-4-5 (or multiples of this) will have this angle. We already saw that in the 6-5-5 example.

Other combinations (that are not 3-4-5 in disguise) that give a 53.1301 angle are:

a b c Comments
2 6.5 7.5
4 13 15 Just double 2-6.5-7.5
5 8.5 10.5
6.5 7 7.5 Angle A

There are actually quite a few of these; I’ve only listed some above. All of those except the last form the 53.130 angle at B.

Half Unit Construction

There are many ways to generate half-unit offsets with technic; here’s one construction you may find handy when trying to make these triangles:


That’s probably the best one I’ve found so far. You can build this with the 1×2 bricks with pins, as shown, or the 1×2 technic bricks (with holes) and separate pins.

Here’s another technique that isn’t quite as elegant but might be handy at times:


The yellow beam and the holes the yellow connector (usually red in real life) form a beam of total length 7.5 (the two holes in the connector are at 6.5 and 7.5).

As shown above the half offset connector is held in place by an axle pin and isn’t necessarily completely stable. You can brace it in a variety of ways if necessary:


That’s it for today’s Lego rambling. Happy Building!

The drawings in posting were created with Bricksmith and rendered using LDView all made possible via LDraw

WSOP Update

Been out in Vegas for a week, played three WSOP events: the shootout, the “turbo” (still has 30 minute levels), and a regular NLHE. Ran well; got third on my table at the shootout (which isn’t in the money – only first is), and min-cashed the other two.

Back to Austin for a break; then next up: WSOP Seniors June 19th.

Showing off with shell “nr” (NumerousApp) command

I wrote some scripts demonstrating what you can do with all the bits and pieces I have now for manipulating NumerousApp metrics from python and shell.

In particular, I was interested in finding the maximum value of one of my metrics:3626358291300704487 (this is the actual NumerousApp metric ID)

I have already installed the python numerous client library and the corresponding shell command “nr” that goes with it (see the github page for details). I also already have my NUMEROUSAPIKEY environment variable set and exported. With all that in place I can read the current value of the metric from a shell prompt like this:

% nr 3626358291300704487

I can read the event stream with the “-E” option:

% nr -E 3626358291300704487

Each line of that output is a (somewhat) human-readable display of a value update event on the metric and looks something like this:

4 @ 2015-05-27T20:12:09.375Z by 9310717522265
3 @ 2015-05-27T19:12:09.348Z by 9310717522265 
2 @ 2015-05-27T18:12:09.207Z by 9310717522265 
1 @ 2015-05-27T17:12:09.373Z by 9310717522265 
0 @ 2015-05-27T15:42:11.373Z by 9310717522265 
518 @ 2015-05-27T14:42:09.254Z by 9310717522265 
517 @ 2015-05-27T13:42:09.116Z by 9310717522265 
516 @ 2015-05-27T12:42:09.317Z by 9310717522265 ...

Rather than parse that output I can ask the “nr” command to only print the value field for each of the events:

% nr -E '3626358291300704487[value]'

From there it’s a simple task to write an awk script that will display the maximum found on stdin:

awk 'BEGIN {max=-999999999} {if ($1>max) {max=$1}} END {print max}'

NOTE: In my script the awk command is all on one line. It’s likely showing up in your browser broken into multiple lines; you need to be careful about those line breaks if you are cutting and pasting this example from your browser display.

That script returns the wrong result if all the input values are negative and below the initial value in the BEGIN statement, so you could do it this way if you prefer:

awk 'BEGIN {max="NOTHING"} {if (max=="NOTHING") max = $1; if ($1>max) {max=$1}} END {print max}'

Again be wary of poorly-located line breaks in your browser display if you copy/paste this.

Given those pieces, finding the max value is a simple pipeline:

% nr -E '3626358291300704487[value]' |
awk 'BEGIN {max="NOTHING"} {if (max=="NOTHING") max = $1; if ($1>max) {max=$1}} END {print max}'

Pretty cool, or maybe somewhat demented.

Sometimes you might not have awk (some linux distributions don’t install it by default), so you could also compute the max with a python program. We know python is on the machine or none of this works, so here’s a version using a python program for the max:

MAXPGM="import sys
maxv = None
for x in sys.stdin:
        xval = int(x)
    except ValueError:
        xval = float(x)
    if maxv is None or xval > maxv:
       maxv = xval


nr -E '3626358291300704487[value]' | python -c "$MAXPGM"

Making this a script with more general options is left as an exercise for the reader.

Of course if we are going  to the trouble of writing a python program we might want to go ahead and write the entire script in python, which might arguably have been simpler. But, this example notwithstanding, it’s still fun to hack around and see how many powerful things you can do with the “nr” command and some shell.

NumerousApp Server API Performance

I added yet another numerous metric, this time tracking the performance of the NumerousApp server itself:

It’s measured using this python code:

import numerous

nr = numerous.Numerous()

t = nr.statistics['serverResponseTimes']
print (int(t*10000)/10.0)"

 which is using my NumerousApp Python library (“pip install numerous”).

I just make two user() API calls (discarding the returned info), then dig into the statistics array provided in the object to get the most recent server response time (measured as “on-the-wire” time). The reason for doing two calls is connection overhead; the first call will be significantly slower because it has to perform a TCP connect and an initial SSL setup; the second call reuses the connection (HTTP keep-alive) and is much faster. The numbers are typically around 300msec for the first API call and 60-70msec for subsequent calls (also varies substantially depending on the particular API).

The single response time in ‘statistics’ is the time from the most recent (i.e., second) nr.user() call. The int and 10000/10.0 hack is just to convert the fractional seconds in milliseconds down to tenths (truncated, not rounded … sue me).