Sorry I'm late. :D
You can make your plots more robust to "can't determine bounds" errors
by including an `invisible-rect' or `invisible-rect3d' renderer in the
plot, with fully specified (i.e. non-#f) bounds. The plots' bounds will
always include the invisible rectangle.
Another option is to explicitly pass #:x-min, #:x-max, etc. keyword
arguments to `plot'. Any bounds you set that way will be fixed.
Do you mind if I ask what you're up to?
Neil ⊥
On 08/11/2013 01:40 PM, J G Cho wrote:
Thanks for the assurance. It helped me to focus on my
world->list-of-vectors It turns out it did not return enough vectors (at
least 2, I think) for initial-world.
On Sun, Aug 11, 2013 at 12:34 PM, Matthias Felleisen
<matth...@ccs.neu.edu <mailto:matth...@ccs.neu.edu>> wrote:
On Aug 10, 2013, at 7:04 PM, J G Cho wrote:
I get an error (somewhat expectedly) when I try
(big-bang init
(on-tick random-walk 1)
;(on-key door-actions)
(to-draw plot-render)
))
where plot-render is defined as
(define (plot-render world)
(p:plot (p:lines
(world->list-of-vectors world)
#:color 6 #:label "Random walk")))
with the following at the top
(require (prefix-in p: plot))
The error msg is
plot: could not determine sensible plot bounds; got x ∈ [0,0], y ∈
[1,1]
Is there way to let plot know of the context? Or pass a context to
plot and extract the pixels and hand it over to via some proc in
2htdp/image? Or maybe there is a simple way?
This works like a charm for me:
#lang racket
(require (prefix-in p: plot) 2htdp/universe)
(define (plot-render world)
(p:plot (p:lines (world->list-of-vectors world)
#:color 6 #:label "Random walk")))
(define (world->list-of-vectors world)
`(#(1 3) #(2 -2) #(4 3)))
(define (random-walk world)
'more-dummy)
(big-bang 'dummy ; init
(on-tick random-walk 1)
(to-draw plot-render))
;; ---
When I had a student implement the first plot version, I
intentionally made sure that plot returned something I could use in
big-bang.
And btw, this works too:
#lang racket
(require (prefix-in p: plot) 2htdp/universe 2htdp/image)
(define (plot-render world)
(overlay
(p:plot (p:lines (world->list-of-vectors world)
#:color 6 #:label "Random walk"))
(square 800 'solid 'blue)))
(define (world->list-of-vectors world)
`(#(1 3) #(2 -2) #(4 3)))
(define (random-walk world)
'more-dummy)
(big-bang 'dummy ; init
(on-tick random-walk 1)
(to-draw plot-render))
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