it with HB. Everytime I reopen the file, the index of the floors has changed. For example if the floor that I want to study is number 3 of, say, 11 indices, the next time I open my GH definition the index has changed to 7. …
t, let's talk about randomness. Randomness is a problem in computing because digital computers are deterministic. If you give them the exact same instructions they always end up with the exact same result. It turns out to be mathematically impossible to generate true random numbers using a digital computer, but it is fairly easy to generate pseudo-random numbers. This is actually not bad news as pseudo-random numbers -unlike real random numbers- can be generated again and again and you'll end up with the same random numbers every time. Being able to get the same random numbers on demand increases the reliability of these number sequences which in turn makes them easier to use.
Pseudo-random numbers are numbers that have certain characteristics. Note that when we talk about random numbers we are really talking about numbers. Plural. It's easy to generate only a single one, as xkcd so eloquently put it:
So what are these characteristics that define pseudo-randomness? Without being actually correct, I can sum them up as follows:
The sequence of generated numbers should never repeat itself*
The numbers in the sequence ought to be spread evenly across the numeric domain**
There are a lot of different algorithms out there, some better than others, some faster than others, some solving very specific problems while others are more generic. The generator used in Grasshopper is the standard Microsoft .NET Random, based on Donald Knuth's subtractive algorithm.
So let's imagine we want random integers between 0 and 10. What would a bad random sequence look like?
3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 (about as bad as it gets)
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 (not random at all)
1 3 2 5 3 9 1 2 4 2 5 1 1 2 8 1 5 2 3 4 (too many low numbers)
2 8 4 6 0 9 8 2 4 8 6 4 2 2 5 1 4 8 6 2 (too many even numbers)
So what about good sequences? Well, here's a few:
6 9 1 2 0 4 2 8 5 7 2 9 1 9 2 5 3 1 9 2 (sure, why not)
6 2 5 3 4 1 9 7 8 0 2 1 6 4 5 8 9 5 0 9 (looks about right)
1 8 5 2 3 4 5 7 9 5 2 1 0 2 1 0 9 7 6 4 (I suppose)
9 0 6 4 8 3 1 5 2 7 6 1 4 6 0 1 9 7 5 6 (whatever)
There are a lot of valid pseudo-random sequences. (Seriously, loads). So even if we have a good pseudo-random generator we may be given a random sequence that isn't entirely to our liking. The shorter the sequence we need, the more likely it is that statistical aberrations invalidate that particular sequence for us. What we need is some control over the generator so we don't just get a repeatable sequence, but a repeatable sequence we actually like.
Enter seed values. The random generator requires a seed value before it can generate a random sequence. These seed values are always integers, and they can be any valid 32-bit integer. Every unique seed value results in the same sequence. Every time.
Unfortunately there is no clear relationship between seeds and sequences. Changing the seed value from 5 to 6 will result in a completely difference random sequence, and two sequences that are very similar may well have to wildly different seeds. There is therefore no way to guess a good seed value, it is completely trial-and-error. Also because of this extremely discontinuous nature, you cannot use tools like Galapagos to optimize a seed value.
If you are looking for a pseudo-random sequence which has custom characteristics, you may well end up having to write your own generator algorithm. Ask questions about this on the Grasshopper main forum or the VB/C# forum.
Conclusion: Seed values are integers that define the exact sequence of pseudo-random numbers, but there's no way of knowing ahead of time what sequence it will be and there's no way of tweaking a sequence by slightly changing the seed. Even the tiniest change in seed value will result in a radically different random sequence.
--
David Rutten
david@mcneel.com
Poprad, Slovakia
* This is not actually possible. A finite amount of numbers always repeats itself eventually.
** This should only be true for long enough sequences, short sequences are allowed to cluster their values somewhat.
Interesting links for further reading:
Coding Horror: Computers are Louse Random Number Generators
StackOverflow: When do random numbers start repeating?…
Added by David Rutten at 9:52am on October 20, 2012
ents will do or which components will be available.
My problem arises because I want to obtain a list such as the following:
{{6, 5, 4, 3, 2, 1, 2, 3, 4, 5, 6}, {5, 6, 5, 4, 3, 2, 1, 2, 3, 4, 5}, {4, 5, 6, 5, 4, 3, 2, 1, 2, 3, 4}, {3, 4, 5, 6, 5, 4, 3, 2, 1, 2, 3}, {2, 3, 4, 5, 6, 5, 4, 3, 2, 1, 2}, {1, 2, 3, 4, 5, 6, 5, 4, 3, 2, 1}}
Which displayed as a matrix is:
If it were possible to combine GH operations (series, shift list, replace string...) with matrices I think it would be quite powerful. A matrix to list component like those available on scientific calculators, would then translate the matrix to list.
For me, matrices come in handy when dealing with surface patterns.
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Added by Jesus Galvez at 6:46am on November 26, 2012
ld be the best UI.
I think difference is made by 'Slider = 10' vs 'Slider = 10.000' more than by simple input/component initialization so, why to stop when it could be even more powerful?
Slider = 0 To 5 --- Slider in [0, 5]
Slider = {3; 0 To 5}
Slider = {3;0;5}
Slider = 3;0;5
Slider = 3 0:5
Slider = 3,0,5
Slider = 3 0 5 --- Value and range (min max)
3 0.0 5 --- 3.0 0.0 5.0
3 0 5.0 --- 3.0 0.0 5.0
3.0 0 5 --- 3.0 0.0 5.0
-1 0 5 --- 0 0 5 (-1 -1 5)
6 0 5 --- 5 0 5 (6 0 6)
Slider = 0:2:6 --- Even numbers: 0, 2, 4, 6.
Slider = 1:2:7 --- Odd numbers: 1, 3, 5, 7.
0:2:5 --- 0:2:4 (or 0:2:6)
3:2:8 --- 3:2:7 (or 3:2:9)
3 1:2:7 --- 1 3 5 7 (value 3)
Bang! = 7 --- 7 outputs
Merge = 5 --- 5 inputs
What's your opinion about Bang! = 7? As it's setting number of inputs, should it use different format? Bang! 7? Bang! (7)? Bang! i7?
+ * - / \ % ^ & | ! = > --- Addition, Multiplication, Subtraction, Division, Integer Division, Modulus, Power, AND, OR, NOT, Larger than, &c.
= could be a problem.
\ Integer division or Set difference?
! could be NOT but also Factorial.
| could mean intersection.
& could mean concatenate.
1+ --- Addition: input A = 1
2* --- Multiplication: input A = 2
+{0,1,1} --- Addition: input B = {0,1,1}
0-, 1/, 2^, 10^, e^ have their own components
Flatten = {7} or Flatten = 7 --- Input P = {7} (off-topic: Why can’t P be a list?)
Pt = {1, 2, 3} --- Point XYZ, X = 1, Y = 2, Z = 3.
Swatch = 129,239,231 (102)
Swatch = 129 139 231 102
F2 = "x^2+y"
"List Length" and "List Insert" don't work properly: "Value List" is choosen. Why? What's the reason to this choice? Well, I'd like to know how the whole thing (search by keywords) works, David.
Name and nickname can be now used as keywords. "Larger" works for ">" but "greater" doesn't. Could it be improved? Could synonyms be used? Could a short description even be used (I know this could be a bit weird)?
more than --- >
more or less --- Similarity
more less --- Similarity
red green --- Sets.List components should be showed
lightning --- Split Tree
What about use Curve.Analysis or Math.Boolean to display those Tab.Panel components? Param, Math, Sets, Vector? Primitive, Special, Util? Tab, Panel, and Tab.Panel as keywords.
At the moment that I write this, I check that ignoring accents in keywords has almost been included (0.8.0009): p`anel, pañel, pánel --- panel (almost)
Shouldn’t 'Dom2' work for Dom²?
What about nested search? You type some keywords (say 'Params' or 'Params.Geometry', or 'red green', or 'lst') and then you make a fine-tunning search over previous results/keywords. Tab.Panel and/or nested geometry could be useful when search by plug-in is desired or when you want to search among .ghuser components (first 'ghuser' or 'Extra.MyPlugIn' or 'lst' keyword and then fine-tunning, specific, search).
Is 'list length' performing this nested search right now ('lst' > 'length')? Anyway, I am thinking about UI (graphical) changes; successive searches.
As I said, description (and even words from the help info) could be used to search. What about "some kind of tags"? I mean that if 'list l' to finally choose List Length has been used for a while, that could be learned. Eventually, an XML file could store these tags, so you could even edit them. That could implement description, name, nickname, help info, Tab.Panel, .ghuser, synonyms (lots of them), tags/shortcuts or wathever.
How could flatten/graft/reverse be used? Initialize graft+Simplify or graft+Bang! could be really useful.
What about expressions? I don't how could it be done properly: would Slider = x^2 (expression) work? I mean, aren't expressions parsed when initializing?
Is Panel somehow doing this? 'panel = wathever' always suppose that wathever is a string, so you can't use 'panel = <pi>'. Sets.Strings components also do this.
I've been about to write several paragraphs about height/width (resizable components: Panel, Graph Mapper, Slider, &c.), input/output names (Scripts, F components; or any component with editable input/output names), orientation (Scribble), type hint and access option, nickname, &c. but, to sum up: being able to set any property when initializing would be really useful. I'd like to know the best choice of syntax but I'm sure that, David, you're closer to the answer. What do you think about this?
Slider: 3 0 5 "MySlider" "Slider^2"
Panel: "This is the content" "This is the title"
VB: "N" List Integer 7 "r" Item Double
Addition: A 1 B 2
I guess that any unified syntax would be elegant and useful, but additional ad hoc syntax (per component) could be even better (cleaner).
What about use lists of values? I'm not sure about format: panel = ("Hello", "Bonjour", "Hola")? If any valid format/syntax is found, maybe more sophisticated fetaures could be achieved: panel = {0;0} ("A", "B", "C") {0;1} ("1", "2", "3") How would you like this to be implemented?
There is a much simpler and interesting feature that would be useful, in my opinion: being able to initialize more than one component. I mean say 7xSlider = 10.0 and get 7 sliders and I also mean multiline (multi-component) initialization: Ctrl+Intro when you want to start a new line and Intro (or even some Accept/Cancel buttons when you activate multiline mode) to initialize (every line/component), for example. I mean:
3 x Slider = 1
Panel
Mass addition
Panel
And the whole bunch of components that were in mind (pre-thinked definition) is initialized. It speeds up the workflow, making more dynamic to add components that are only available via the drop-down panels.
Should this multiplier be something like a text box adjacent to search field more than '7x'?
These are some of my thoughts about intitializing. Please let me know your opinion :]
…
shift. I realize I can use 'replace branch' but I do not have an available mask to utilize. I have simplified the problem to its simplest form so my question is understandable, however, the tree I am trying perform this operation on is a much larger 3 digit path address.
{1;3;2}
{2;3;4}
{3;5;4}
{4;3;7}
Change the above list to the list below.
{0;3;2}
{1;3;4}
{2;5:4}
{3;3;7}
I wish for a more robust arsenal of branch manipulation components. Most of the things I need to do are possible with the existing components, however, many operations take several components to perform even simple manipulations. Since branch/path manipulation is so integral to using GH successfully, it seems the GH community would be well served by enhancing the available path manipulation components.
Thanks,
Stan
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tName_FinalProject_PartD.pdf
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ouldn't the surface component only accept the number 8? it accepts 5 and 7. the grid is 7 points in the x direction and 5 points in the y direction. so shouldn't the u count be either 6 or 8?
it works with the u count at 5. i just don't understand why.
thank you so much for your patience with my questions.
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Added by pwdarden to gHowl at 6:18pm on September 21, 2013