In functional languages, you don't really delete so much as you make a fresh copy absent of the undesirable elements.
Where you looking for this? ] a=. <"0 'abcdef' ┌─┬─┬─┬─┬─┬─┐ │a│b│c│d│e│f│ └─┴─┴─┴─┴─┴─┘ 0 0 1 1 0 1 # a ┌─┬─┬─┐ │c│d│f│ └─┴─┴─┘ On Tue, May 19, 2020, 07:27 HH PackRat <[email protected]> wrote: > Feel free to skip this apologetic preface that applies to all questions I > ask: > > By way of excuse, I'm 74, and my memory has been failing little by > little over the last number of years. I looked at some J code I had > written 8-12 years ago and was astounded at what I used to be able to > do--nothing major, mind you, but yet good, decent code! I've been > sort of a lifetime "beginner" since 2006 (maybe reaching "advanced > beginner", if there is such a thing!), doing programming on and off as > I have need (which also doesn't help the memory). However, comparing > what I wrote years ago with what I struggle with now is showing that > my memory of what certain J primitives and combinations do is slipping > with time. (Years ago I wrote my own beginner-level task-organized > vocabulary of the kinds of things I typically need to do in my > particular programming interests, and I heavily depend upon that until > I run into something where the issue is not addressed in my > compilation.) So, please bear with me when I ask questions with > simple answers that you may think everybody should already know. I've > been a hobbyist programmer since 1975, mostly with versions of BASIC. > (I started with a MITS Altair PC and Microsoft's original BASIC. A > good number of years ago I asked Bill Gates to autograph my manual for > that BASIC since he wrote the code.) But times have changed, and now > I simply LOVE working with the J language because it fits my needs so > well in developing relatively simple programs (without writing all > those loops!), especially for dealing with data and such in my stock > market (and other) interests. I have no need to make my code tight, > fast, or short, as perhaps most of you need to do in your work--for > me, it just has to work correctly! > > After all that, finally, my QUESTION: > > J has all sorts of ways of creating, assembling, disassembling, > selecting, changing, and finding data in atoms, lists, and tables. > However, in no index of any of my books or ebooks about J, nor in the > (old) Vocabulary, nor in NuVoc have I been able to find how to DELETE > tables or any of their rows. > > For example, here is the cleaned up (of double quotation marks) > beginning of unusually-formatted data from a particular data source > that I'm trying to reformat according to standard: > > +---------|-----------|-- > |May 08|May 07| > +---------|-----------|-- > | 2020 | 2020 | > +---------|-----------|-- > | 664.35| 652.35| > +---------|-----------|-- > | 660.21| 653.00| > +---------|-----------|-- > | 664.56| 657.12| > +----------|----------|-- > | 657.67| 651.29| > +----------|-----------|-- > | - | - | > +----------|-----------|-- > | 1.84% | 1.19% | > +----------|-----------|-- > > I need to delete rows 0, 1, and 7--how to do that? (that is, leaving > a new table of rows, formerly 2 to 6, now 0 to 4) > > One thought I had was maybe to use some sort of boolean mask > expression using either 00111110 or its opposite 11000001. But, even > using that in some way, I still don't know how to physically get rid > of those rows, so that they don't exist any more. This question and > its answer is probably a "piece of cake" for most of you, but, right > now, the answer is not obvious to me. (After seeing one or more > answers, I'll probably say to myself, "Of course! I should have known > that!") > > By the way, just FYI, the first two deleted rows will be replaced with > the row that was created in the question in my previous message, but > that replacement is not what this question is dealing with--I'm rather > sure I can deal with that without help at this point. After that, > it's just a matter of moving one of the price rows to a different > position, converting the hyphens to zeros, and chronologically > reversing the data. I've never moved and inserted a row before, but I > think I'll be able to figure that one out. (If not, you know I'll be > back.) ;-) > > Again, thanks in advance for your help with this! > > Harvey > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
