Just a little note: Replacing stuff with underscores should be used with care, as the resulting variable names might collide with stuff in locales.
eg: a name as 'foo##bar' would end up being foo__bar, and assigning something to this variable ends up with an value error on bar. If bar existed before, you can get all sorts of errors, but you won't end up with a variable named 'foo__bar' for sure. Just to say, we'd better take something that has no special meaning instead of _, which is sort of hard to find in J... x's all the way maybe? Jan-Pieter 2014-05-26 10:39 GMT+02:00 'Pascal Jasmin' via Programming < [email protected]>: > 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
