openscad list comprehension

list-comprehension-demos dotSCAD; Project: 2: Mentions 25: 83: Stars 566-Growth -10.0: Activity 9.9: about 3 years ago: Latest Commit: 4 days ago: OpenSCAD: Language OpenSCAD-License: GNU Lesser General Public License v3.0 only In many functions in my code, this has removed the need for recursive calls to concat(): In many functions in my code, this has removed the need for recursive calls to concat(): No description, website, or topics provided. This is a general purpose OpenSCAD library for easily creating diverse shapes by simply creating lists of points which trace out layers in an outline of the desired shape. When a function argument is missing in a function call, an undef value is assigned to it in evaluating the function expression. On the flip side, subtle inconsistencies make a notation harder to understand and reason about, and increase the probability of making a mistake. Is there a reason why list comprehensions can't have a comma separated list of elements after the for(..) instead of the just a single element? The word 'matrix' consistently means an array of arrays of numbers (aka an array of vectors, in the more specific sense of the word vector). In particular it contains a user-space sweep() module which can be used to sweep a 2D shape along a 3D path. learn about Codespaces. To avoid this, a default value may be . OpenSCAD 2015.03 has just been released! List Comprehensions. Notice how the 2 lines above are structurally the same, and in OpenSCAD2 the 'for' operator has the same semantics in both cases. When a function argument is missing in a function call, an undef value is assigned to it in evaluating the function expression. Inconsistent terminology bugs me, but I may be in the minority about this. Here are examples of my proposed OpenSCAD array comprehension syntax: [ for (x = [1:10]) assign (n = x*x) if (n % 2 == 0) n ] // [4,16,36,64,100] [ for (x = [0:5]) x*x ] // [0,1,4,9,16,25] [ for (i = [1:4]) for (j = [1:4]) i==j ] // 4x4 identity matrix On 11 April 2014 17:03, Oskar < [hidden email] > wrote: n/2: if(n>=0) n ]); // this would generate a syntactical error, // even numbers are halved, positive odd numbers are preserved, negative odd numbers are eliminated. [ for ( a=inita,b=initb, ; condition ; a=nexta,b=nextb, ) expr ], (Or you could convert this to tail recursion, like in Torsten's code.). The for element iterates over all the members of the list. Nabble removed Mailing-list integration from the Forum. The if-else construct is equivalent to the conditional expression? There are different ways to define nested loops. each unwraps ranges and helps to build more general for lists when combined with multiple generator expressions. A tag already exists with the provided branch name. On Jun 1, 2014, at 15:33 PM, kitwallace <, On Jun 2, 2014, at 19:06 PM, kitwallace <. It isn't reassignment! The library consists of modules for creating polyhedrons from these lists of points, as well as functions to assist in specifying the points using transformations. I made a mistake in one of my examples, for my proposed syntax for array comprehensions. One should not expect to do many things one would do with most programming languages. Sent from the OpenSCAD mailing list archive at Nabble.com. This allows to easily construct lists from multiple sub lists generated by different list comprehension expressions avoiding concat. // ECHO: [[-2, -1], [0, 0], [1, 1], [2, 1], [3, 3], [4, 2], [5, 5]]; // even numbers are dropped, multiples of 4 are substituted by -1, // odd numbers are dropped, multiples of 4 are substituted by -1, // ECHO: [[1, 1, 2], [2, 4, 8], [3, 9, 18], [4, 16, 32]], // nested loop using multiple for elements, // nested loop to generate a bi-dimensional matrix, // ECHO: [[1, 0, 0], [0, 1, 0], [0, 0, 1]], // output: list with the outer level nesting removed, // use seed in rands() to get reproducible results, // [[0, 0], [2, 2], [4, 4],[4, 4], [2, 2], [0, 0]], // [[4, 4], [3, 3], [2, 2], [1, 1], [0, 0]], //concatenates two OpenSCAD lists [1,2,3] and [4,5], giving [1, 2, 3, 4, 5], Last edited on 22 September 2022, at 14:12, https://en.wikibooks.org/w/index.php?title=OpenSCAD_User_Manual/List_Comprehensions&oldid=4112565. Deeper dimensions can be accessed by nesting for elements. extrusion.scad https://github.com/openscad/openscad/wiki#list-comprehensions, http://forum.openscad.org/List-comprehensions-tp7644.html, http://rocklinux.net/mailman/listinfo/openscad, http://forum.openscad.org/List-comprehensions-tp7644p7664.html, https://gist.github.com/OskarLinde/9916181/revisions, https://github.com/openscad/openscad/wiki/List-Comprehensions, https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/List_Comprehensions. To avoid this, a default value may be assigned to optional . You signed in with another tab or window. Yes, the 'each' operator is verbose. Now it is hard to imagine what it can't do. Other OSs and Versions. You don't have access just yet, but in the meantime, you can Example: Based on a list of fruits, you want a new list, containing only the fruits with the letter "a" in the name. The first is a list expression, the second is a "statement" (in OpenSCAD) or an "object expression" (in OpenSCAD2). The functions that Torsten wrote to generate Runsun's sequence are anamorphisms. Use Git or checkout with SVN using the web URL. That's not a compelling reason for you to add it right now, it only really makes sense later, assuming we decide to use the backward compatibility scheme that I outline in the design doc. openscad Fetched on 2022/07/11 22:09 openscad / list-comprehension-demos View it on GitHub Star 83 Rank 197468 Released by @k0kubun in December 2014. So I don't want that interface in OpenSCAD. If nothing happens, download Xcode and try again. List comprehensions in OpenSCAD are, from what I understand, limited to taking a list as input, performing an operation on the individual elements (and even doing the operation may be conditional depending on the contents of the element), and returning a list. The list comprehension syntax is generalized to allow multiple expressions. So I agree. Looks like a step too far (backwards) towards C++ to me.". The Open3D -ML library welcomes more state-of-the-art models and operators that are ready to use for advanced 3D perception, especially semantic segmentation, including. In OpenSCAD, I'd like to create a string, pattern, that starts with 'a', ends with 'c', . list-comprehension-demos; Project: 12: Mentions 1: 472: Stars 78-Growth -9.7: Activity 10.0: 11 days ago: Latest Commit: over 2 years ago: OpenSCAD: Language OpenSCAD: GNU Lesser General Public License v3.0 only: License- To test the comprehensions in some real code, I converted a module to use them as much as possible. triangles : concat(start_cap, triangles, end_cap)); stl files provided for convenience :) The sequence to the right of the equals sign can be any list. Also, to step a bit into the direction of. The sequence to the right of the equals sign can be any list. Generate [ for (i = range|list) i ] Generate [ for (init;condition;next) i ] Flatten [ each i ] Conditions [ for (i = ) if (condition (i)) i ] Conditions [ for (i = ) if (condition (i)) x else y ] Assignments [ for (i = ) let (assignments) a ] This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository. The syntax is the same as used by the for iterator. Here is a user-defined function that flattens a nested vector. This killed the Forum. They way I think of it is that OpenScad has lists but they can be used to represent arrays, vectors and matrices when populated accordingly. The syntax is the same as used by the for iterator. In addition, concat() can be used to concatenate lists. The list comprehensions provide a flexible way to generate lists using the general syntax, The following elements are supported to construct the list definition. All we need is a single line of code. If I unterstand your question well, there is a good work-around for this. I think it quite well shows how the syntax would behave in real code: Excellent! OpenSCAD now support list comprehensions. It's not reassignment. OpenSCAD support is now provided by the Mailing List. The if element allows selection if the expression should be allocated and added to the result list or not. New state-of-the-art Point Transformer for Semantic Segmentation. Beyond this, functional programming theorists have identified a number of commonly occurring patterns of recursion, and designed high level control structures that encapsulate these recursive patterns. Since Javascript also contains the for (..;..;..) operator, you could also say it's a step too far towards Javascript. Most prominent are text (), offset () and list comprehension functionality, as well as a better editor and other GUI improvements implemented during last year's Google Summer of Code. Several common usage patterns are presented here. _______________________________________________. As a quick refresher, a list comprehension is a way to create a new list by filtering elements in a list that meet a condition, transforming the elements as desired and storing the new values in a list. With recursion you don't need iteration. Even a complicated algorithm Quicksort becomes doable with for(), if(), let() and recursion: select() performs selection and reordering of elements into a new vector. Dense RGB-D SLAM with a GUI ; See this tutorial for more details. This page was last edited on 22 September 2022, at 14:12. Tutorial Get started with OpenSCAD. In my proposed syntax for list comprehensions, there is a [ ] surrounding the construct, and if you want to generate a list of lists, then there will be an inner set of [ ] as well, like this: I think this is an important property of the notation. If the sequence has more than one dimension, for iterates over the first dimension only. 1 : 0 ]; f = [ for (x = [1:10]) assign (n = x*x) if (n % 2 == 0) n ] // [4,16,36,64,100]. But I agree, recursive functions are a pain to write, and there is high level syntax that is easier to write and which can replace the use of recursive functions in some common cases. [for (i=1,n=1; i <= 4; i=i+1, n=(n+i)*i) n]. Caring about undef [edit | edit source]. Using list comprehension, a parametric equation can be calculated at a number of points to approximate many curves, such as the following example for an ellipse (using polygon()): List comprehension can be used in a user-defined function to perform tasks on or for vectors. The list comprehension syntax is generalized to allow multiple expressions. Best, . It is a definition of an ordered set; think of it as for_all(). Unfortunately, it was a little too limited, the recent addition of list comprehensions has been a huge addition to OpenSCAD. This is now an ARCHIVE. b= [ [2,9,10], [3,7,15], [5,12,12], [15,20,10], [19,24,8]] print ( [ (R, 0, 0) for _, R, _ in b]) We have output [ (9, 0, 0), (7, 0, 0), (12, 0, 0), (20, 0, 0), (24, 0, 0)] python-3.x set Share Improve this question edited 6 hours ago asked 6 hours ago Wei-Cheng Lee 1 1 New contributor I'm trying to make an adapter to attach the ~1 inch hose outlet on my radial arm saw to the ~2 inch hose on my shop vac. There was a problem preparing your codespace, please try again. This killed the Forum. . If nothing happens, download GitHub Desktop and try again. Any thought of accessing the item(s) generated (still in the buffer), in the middle of looping, before the loop is completed ? I think that both of these properties are important, because notation is a tool of thought, and a well designed notation assists the user in thinking about a problem, rather hindering them. The recursive equivalent of this generator is. changes to skin.scad required (as per openscad/list-comprehension-demos#8): change signature to module skin(profiles, no_endcaps=false) change last line to polyhedron(convexity=4, points=profiles, faces = no_endcaps ? 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