The prefixing idea would not preclude using an empty vector as the prefix, assuming the column names are all valid J variable names.
On Tue, May 27, 2014 at 2:43 AM, Ric Sherlock <[email protected]> wrote: > I think both of your points come back to the fact that you see there are > situations where prefixing the field names in the header would be useful > and I like your use of nl to group fields. > > I agree these are sometimes desirable and my approach facilitates prefixing > if desired (as shown in previous post) but doesn't mandate it for all > fields. However for (my) most common usage, no prefixes is preferable. > > Raul's validation is simpler but doesn't cover a couple of edge cases. For > example the name 'prot(bv)' would be forced to prot_bv_ . This would assign > fine but would now be located in the new locale bv. > 'Name (first)' would be forced to Name__first_ which is an "ill-formed > name". > > Cheers, > > > On Tue, May 27, 2014 at 12:26 AM, 'Pascal Jasmin' via Programming < > [email protected]> wrote: > > > a couple of reasons to prefer Raul's approach, beside the simpler > > validation: > > > > 1. you get to prefix the "fields" with the "table name" > > > > (;:'a 1.1 b') 'col' masgn i.3 3 > > 0 1 2 > > 3 4 5 > > 6 7 8 > > > > 2. You can use nl based code for group operations on the fields > > > > 'col' nl '' > > ┌──────┬────┬────┐ > > │col1_1│cola│colb│ > > └──────┴────┴────┘ > > (] ,. ". each ) 'col' nl '' > > ┌──────┬─────┐ > > │col1_1│3 4 5│ > > ├──────┼─────┤ > > │cola │0 1 2│ > > ├──────┼─────┤ > > │colb │6 7 8│ > > └──────┴─────┘ > > > > > > > > ----- Original Message ----- > > From: Ric Sherlock <[email protected]> > > To: Programming JForum <[email protected]> > > Cc: > > Sent: Monday, May 26, 2014 7:08:40 AM > > Subject: Re: [Jprogramming] Multiple assignments > > > > Here is my solution based on the discussion. I don't think that I'd want > to > > prefix the header names normally. For me a lot of the benefit of > assigning > > the columns to the header is that my code becomes more readable. This get > > spoilt a bit when all the names have prefixes. However assign2hdr takes > an > > optional left arg of the header names, so if you wanted to add a prefix > > then that is possible at that point. > > The solution below doesn't yet handle the problem with header names > > colliding with local names that spawned this thread. > > > > forceLeadingAlpha=: ,~ 'X' {.~ [: -.@e.&Alpha_j_ {. > > replaceNonAlpha=: (-.@e.&AlphaNum_j_)`(,:&'_')} > > deus=: #~ (+. (1: |. (> </\)))@('_'&~:) NB. delete extraneous > > underscores > > coerce2Name=: deus@replaceNonAlpha@forceLeadingAlpha@deb > > > > assign2hdr=: 3 : 0 > > > > 'hdr dat'=. split y > > > > hdr assign2hdr dat > > > > : > > > > hdr=. uniqify_pdsv_ coerce2Name_pdsv_&.> x > > > > dat=. |: makenumcol y > > > > idx=. I. 2 ~: (3!:0)&> {."1 dat > > > > ((<<<idx){hdr)=: <"1 (<<<idx) { dat > > > > (idx{hdr)=: idx { dat > > > > EMPTY > > > > ) > > > > > > On Mon, May 26, 2014 at 8:55 PM, Raul Miller <[email protected]> > > wrote: > > > > > That sounds like a good idea. > > > > > > Except I think we need three parameters: > > > list of names > > > disambiguating prefix > > > list of values > > > > > > I think I'd like the list of names be x, the prefix be adverb argument > > and > > > the list of values be y. > > > > > > So here's an implementation: > > > masgn=:1 :0 > > > : > > > bad=.a.-.;'0Aa' ([ (+ i.) 1 + -~)&.(a.&i.)&.> '9Zz' > > > names=. ('_' I.@e.&bad@]} m&,)&.>x > > > (names [erase 'names bad x y')=: y > > > ) > > > > > > Example use: > > > > > > (;:'a 1.1 b') 'z' masgn i.3 3 > > > 0 1 2 > > > 3 4 5 > > > 6 7 8 > > > za > > > 0 1 2 > > > z1_1 > > > 3 4 5 > > > zb > > > 6 7 8 > > > > > > Of course I probably went a little overboard here with the > > implementation. > > > So feel free to strip out parts you don't need. And maybe add a 0 0$ at > > the > > > beginning of the result line, if you do not like results. > > > > > > Thanks, > > > > > > -- > > > Raul > > > > > > > > > > > > On Mon, May 26, 2014 at 4:39 AM, 'Pascal Jasmin' via Programming < > > > [email protected]> wrote: > > > > > > > The way I would do it would be to add a prefix passed from x > parameter, > > > > and replace spaces (or illegal characters ') with underscores. > > Assuming > > > > other illegal characters are rare should be fine, but the advantage > of > > > > prefixing all columns helps both in preventing collisions with > general > > J > > > > names, and allows processing multiple such files without collision. > > > > > > > > > > > > ----- Original Message ----- > > > > From: Ric Sherlock <[email protected]> > > > > To: Programming JForum <[email protected]> > > > > Cc: > > > > Sent: Sunday, May 25, 2014 4:20:16 PM > > > > Subject: Re: [Jprogramming] Multiple assignments > > > > > > > > I recently released an update to addons/dsv that contains a new > > utitlity: > > > > assign2hdr > > > > > > > > testcsv=: noun define > > > > # The following is an example of a comma-separated file with > > > > # comment lines at the start of the file indicated by the fact they > > > > > > > > # start with the # symbol. > > > > > > > > id,bar code,name > > > > > > > > 24582621,119533,DELTOP DAVINCI > > > > > > > > 25422991,155439,AMBZED ROSCOE S2F > > > > > > > > 25784612,135624,TEF SHADOW BLARIS > > > > > > > > 22063188,102545,BIG P BLONDEL PRIM > > > > > > > > 20803506,137609,MONGA FLOL > > > > > > > > 27360900,107865,FRAMBIN R NOGN ET > > > > > > > > ) > > > > > > > > > > > > fixcsv testcsv > > > > > > > > +--------+--------+------------------+ > > > > > > > > |id |bar code|name | > > > > > > > > +--------+--------+------------------+ > > > > > > > > |24582621|119533 |DELTOP DAVINCI | > > > > > > > > +--------+--------+------------------+ > > > > > > > > |25422991|155439 |AMBZED ROSCOE S2F | > > > > > > > > +--------+--------+------------------+ > > > > > > > > |25784612|135624 |TEF SHADOW BLARIS | > > > > > > > > +--------+--------+------------------+ > > > > > > > > |22063188|102545 |BIG P BLONDEL PRIM| > > > > > > > > +--------+--------+------------------+ > > > > > > > > |20803506|137609 |MONGA FLOL | > > > > > > > > +--------+--------+------------------+ > > > > > > > > |27360900|107865 |FRAMBIN R NOGN ET | > > > > > > > > +--------+--------+------------------+ > > > > > > > > > > > > assign2hdr fixcsv testcsv > > > > > > > > bar_code > > > > > > > > 119533 155439 135624 102545 137609 107865 > > > > > > > > > > > > It does try to automatically coerce names, but does so by removing > > > leading > > > > blanks and any leading chars that aren't valid starting chars for a > > name. > > > > Adding as 'X' in front may be better than that. > > > > > > > > On May 26, 2014 5:04 AM, "Devon McCormick" <[email protected]> > wrote: > > > > > > > > > Assigning column names this way can be very useful. However, it > > > requires > > > > > that column names be valid J variable names. The R programming > > > language > > > > > has a feature like this that includes automatic coercion of invalid > > > names > > > > > for at least a couple of simple cases - something like changing > > > embedded > > > > > spaces to underscores and prefixing any name beginning with a > numeral > > > > with > > > > > "X". > > > > > > > > > > It might be useful to publicize a simple set of conversions like > this > > > > for J > > > > > names on the wiki so that there's at least a stab at > standardization. > > > > > > > > > > > > > > > On Sun, May 25, 2014 at 12:58 PM, J. Patrick Harrington > > > > > <[email protected]>wrote: > > > > > > > > > > > I've always liked this economy of assignment: > > > > > > 'e f g'=. s=. >1 2;3 4;5 6 > > > > > > f > > > > > > 3 4 > > > > > > e > > > > > > 1 2 > > > > > > -- but I wondered if it were possible to extend this where the > left > > > > hand > > > > > > side is not explicit: > > > > > > abc=. 'a';'bb';'ccc' > > > > > > ┌─┬──┬───┐ > > > > > > │a│bb│ccc│ > > > > > > └─┴──┴───┘ > > > > > > I found I could make a single assignment: > > > > > > (>1{abc)=. 1{s > > > > > > bb > > > > > > 3 4 > > > > > > a > > > > > > |value error: a > > > > > > But I didn't want to put this into a loop. > > > > > > It was neat to find that I could write: > > > > > > (abc)=. s > > > > > > a > > > > > > 1 2 > > > > > > bb > > > > > > 3 4 > > > > > > ccc > > > > > > 4 5 > > > > > > abc > > > > > > ┌─┬──┬───┐ > > > > > > │a│bb│ccc│ > > > > > > └─┴──┴───┘ > > > > > > This is useful in working with data files output > > > > > > by a stellar evolution program where I have ASCII tables with 90 > > > > columns > > > > > > and over 1000 rows, and each > > > > > > column has a name 1 to 25 characters long: I wanted > > > > > > to read this into a J session, assigning the column > > > > > > values to each of the respective names. Turns out it > > > > > > can be done with one line of the form > > > > > > (head)=: data_array > > > > > > where > > > > > > head > > > > > > ┌────┬────┬──────┬────┬────┬──────────┬────────┬──────────── > > > > > > ─────────────┬───────────────────┬─ > > > > > > │zone│logT│logRho│logP│logR│luminosity│eps_grav│log_abs_ > > > > > > eps_grav_dm_div_L│signed_log_eps_grav│.. > > > > > > └────┴────┴──────┴────┴────┴──────────┴────────┴──────────── > > > > > > ─────────────┴───────────────────┴─ > > > > > > (see http://www.astro.umd.edu/~jph/mesa_read.ijs) Another > example > > of > > > > the > > > > > > "black hole of J". > > > > > > > > > > > > I don't know where in the documentation this can be > > > > > > found - I just got there by experimentation. > > > > > > > > > > > > Patrick > > > > > > > > > > > > P.S. This started as a post asking for > > > > > > help in getting rid of a loop, but > > > > > > I found the solution along the way. > > > > > > > > > ---------------------------------------------------------------------- > > > > > > For information about J forums see > > > http://www.jsoftware.com/forums.htm > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > Devon McCormick, CFA > > > > > > > > > > > > > > > > > > > > > > > > > ---------------------------------------------------------------------- > > > > > For information about J forums see > > http://www.jsoftware.com/forums.htm > > > > > ---------------------------------------------------------------------- > > > > For information about J forums see > http://www.jsoftware.com/forums.htm > > > > > ---------------------------------------------------------------------- > > > > For information about J forums see > http://www.jsoftware.com/forums.htm > > > > > > > ---------------------------------------------------------------------- > > > For information about J forums see http://www.jsoftware.com/forums.htm > > > > > ---------------------------------------------------------------------- > > For information about J forums see http://www.jsoftware.com/forums.htm > > ---------------------------------------------------------------------- > > For information about J forums see http://www.jsoftware.com/forums.htm > > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > -- Devon McCormick, CFA ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
