A good print command needed?

[Arnab Chakraborty]

Dear J-ers,

   As a dabbler in J, I am often bothered by the lack of any output mechanism in J that will allow me to inspect if two objects are equal (as determined by =). 

  One such example is 

   x=.1

   y=.,:1

   x

   y

Both x and y will print as 1. I need to print $x and $y to see the difference.

Just today I have come across another similar situation that is still puzzling me. I have two objects, good and bad:

   good
┌─┐
│1│
└─┘
   bad
┌─┐
│1│
└─┘

Both print the same, as you see. Both are atomic:

   $good
NB. Empty

   $bad
NB. Empty

Yet they are not the same:

   good=bad
0

Let's look inside the boxes:

   (>good)=(>bad)
1
  

Now they are the same! So where can the difference possibly be? 

I have not shown how I got good and bad (they are the results of some complex math procedure that is irrelevant here).

 

My question is: How to debug in such a situation? More specifically,  I want to make a feature request to have a print command that provides a visual representation that is faithful to the = operator. 

  

Thanks and regards,

Arnab

[Arnab Chakraborty]

UIUA-style corner pieces while printing an array might be a good idea to bring out leading 1s in the shape.

To unsubscribe from this group and stop receiving emails from it, send an email to forum+un...@jsoftware.com.

[bill lam]

For named nouns, you can use 5!:5 to visualize the content

   x=. 1
   y=. ,:1
   x=y
1
   5!:5<'x'
1
   5!:5<'y'
,1

To unsubscribe from this group and stop receiving emails from it, send an email to forum+un...@jsoftware.com.

[Arnab Chakraborty]

Thanks a lot, Bill. Now I can understand. The 1 inside the box of good was an atom, while that inside bad had shape 1.

But does this not point at a serious inconsistency?

1 and ,:1 are considered to be the same by = and yet once boxed they are flagged as different by =

Is this a feature or a bug?

[bill lam]

The rank of the verb = is 0 meaning it compares atom by atom

when comparing 1 and ,1  the two nouns are extended to the same shape.

For testing equality between nouns, sometime the verb -: (match) is more appropriate

depending on what you want. eg

   1 -: ,1
0

[Arnab Chakraborty]

Ah, the "strange" behavior of = is a feature after all, as I just now learned from my umpteenth perusal of the nuvoc. Yet another thing to wrap my brain around!

[Arnab Chakraborty]

Wonderful, Bill, you are -:-. (match less)

[More Rice]

Are you looking for Bob's "Enhanced J Display"?

https://code.jsoftware.com/wiki/User:Bob_Therriault/Enhanced_J_Display

(a video of it)

I never tried, but it looks really cool.

Maurice

[Henry Rich]

Consider using Dissect to examine your result.

Henry Rich