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[求助] 在看例子时有几个问题看不懂

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发表于 2012-6-20 08:59:43 | 显示全部楼层 |阅读模式
新手,在看netlogo自带的例子时,有几行程序看不懂,希望高手能够指点。( u* S1 l/ ~# b
netlogo自带的social science--traffic grid这一例子当中,
" x  a3 y# u- fglobals6 D1 V" t3 b7 A# R) h3 h
[
: l. o1 @9 |0 Y& p; r4 s  grid-x-inc               ;; the amount of patches in between two roads in the x direction
$ L9 Q* I: F8 j1 z7 H  grid-y-inc               ;; the amount of patches in between two roads in the y direction6 @8 x& O( a* X
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
+ d* t. g4 i  t4 D* `6 a! I4 p                           ;; it is to accelerate or decelerate
: D0 W( B" |" `* X# M  phase                    ;; keeps track of the phase$ n; c7 s  \) w4 }* J# X8 `7 }( h  F
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure8 Z' X# {* M  r( F8 j
  current-light            ;; the currently selected light
8 p7 c# b& H  y/ O) z6 u/ w, b4 [$ {  W6 e
  ;; patch agentsets
% {3 @* V' d9 _$ x. H7 i9 N/ M8 K  intersections ;; agentset containing the patches that are intersections
  m, F4 G( k5 b3 G0 ~/ m  g  roads         ;; agentset containing the patches that are roads4 G1 N) q7 F& b
]
% g! F3 y: R* y/ Z2 _' Z6 [7 u) D' r! L' R) @1 m/ S
turtles-own
; X" S; Q- `# y% j[
$ x, l) F2 R: P  speed     ;; the speed of the turtle: F- m) x  q' f
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
* w9 F: l) {) C' l" `4 U+ ^4 i" x4 }  wait-time ;; the amount of time since the last time a turtle has moved2 n' H- N  _4 S: G
]! J' n3 r; i* ?

) j) M( e, |6 [% c; `patches-own0 i# ~, F) V5 m% ~: i- W6 p) D
[! _% U/ f# ?+ B  b5 Z
  intersection?   ;; true if the patch is at the intersection of two roads& r/ D# J3 `& b+ \; v
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
6 ~! B* G) b; @# q- B                  ;; false for a non-intersection patches.
+ m. z) K$ \$ s  my-row          ;; the row of the intersection counting from the upper left corner of the
# A$ B2 v- }6 v: A                  ;; world.  -1 for non-intersection patches.: O8 u# N& W: {8 \( ~
  my-column       ;; the column of the intersection counting from the upper left corner of the* y/ R  u. |. f
                  ;; world.  -1 for non-intersection patches.# [( U: `' C& A& g
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.! a5 h7 @* u0 ]0 Q
  auto?           ;; whether or not this intersection will switch automatically.. R- t7 J" d2 \' X; h+ @, h
                  ;; false for non-intersection patches.  Q0 ~( L3 |' L9 T% H& r+ T
]1 |" q! K9 a: \; r

& Z0 I+ _0 l% @
/ h+ `8 G, O3 k$ U' U;;;;;;;;;;;;;;;;;;;;;;. p  B7 ~/ d- P9 l1 @8 E" I: [5 J
;; Setup Procedures ;;
: }8 D# |) v0 }8 _! N;;;;;;;;;;;;;;;;;;;;;;7 S& O( Y9 d: f7 F( g& C

$ ?5 Y* ^8 \8 J( k: w;; Initialize the display by giving the global and patch variables initial values.% `" X; |5 Z- H4 m+ k8 E
;; Create num-cars of turtles if there are enough road patches for one turtle to. B2 j/ f; l  d
;; be created per road patch. Set up the plots.
) n/ j' k  ~* Q! Mto setup
3 b# ^0 G$ \$ s  ca
$ x0 Y6 n5 i1 w2 U5 u/ J: t  setup-globals, x& `6 a2 R& s' M' s

9 X4 B) y: k* \+ |  ;; First we ask the patches to draw themselves and set up a few variables
' i* I" B; R+ l0 U  v" m9 H  setup-patches' o: b/ W" N- Z
  make-current one-of intersections
' j0 }( |; [1 c# @- b  label-current+ ?1 ]! C% K* V- ]/ `( h( V$ j
' }* r; U+ [6 r" l+ O3 ?% X9 z( e
  set-default-shape turtles "car"
+ E& J, H, Q5 X1 |1 z3 ~0 i; V7 z2 W& n) c; C. H$ E
  if (num-cars > count roads)
" k' I+ V" u$ Z+ Z- T, p  [
3 k' ^2 V, r8 u    user-message (word "There are too many cars for the amount of "1 a4 \) T5 X2 l  d+ P
                       "road.  Either increase the amount of roads "
' Q6 ?! k- M; G9 C. u, w$ l  ?                       "by increasing the GRID-SIZE-X or "
4 M) F9 m3 y3 b' v& U                       "GRID-SIZE-Y sliders, or decrease the "+ ]7 ?5 n! x. c5 t* \+ O+ t
                       "number of cars by lowering the NUMBER slider.\n"/ w: {/ O; i& X
                       "The setup has stopped.")
9 M9 W, f3 U. Y! h. B6 l    stop* \! k6 G+ a# i5 F( o* _2 A/ [
  ]& F  b( t" c$ B5 Q+ h6 x6 S
# H! N1 E. C3 a  J# E& u$ F$ ~
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
' N5 q  @3 P" G2 h+ S3 K5 l  crt num-cars$ T1 l8 ^) N5 C2 [" d! z
  [8 H- d% @. q3 i1 t& A5 T  F' Q
    setup-cars
( e& F! u: J# j) }' `$ P    set-car-color
1 ?  S. ]) c( p    record-data* q" |; v! j& s
  ]: p: _- A' C2 r4 y) k2 ]
0 z6 o% O+ o* F8 ?
  ;; give the turtles an initial speed/ ^, G; r, ?8 J* H" u! U
  ask turtles [ set-car-speed ]' T8 I; H6 C# G4 f, I

* ]: g- |; ~3 Y4 y1 x5 g5 H  reset-ticks9 u- D. C. y9 J
end
% a1 L* J3 h" H8 g
$ F$ \6 {, K' Y, P* z1 S7 o;; Initialize the global variables to appropriate values! C, {8 k+ r4 v% J
to setup-globals
, V1 F: r( a1 N; C; S  set current-light nobody ;; just for now, since there are no lights yet
' D' D8 V: J- Y3 U  set phase 0( l) O; D8 w; r7 o6 [& I# `$ G
  set num-cars-stopped 0
- T1 E* [- B! N! ^4 {: a  set grid-x-inc world-width / grid-size-x
' h: |3 J  d2 D: n6 G" F' q8 l' z  set grid-y-inc world-height / grid-size-y
9 v5 R: K" D: j7 X$ U* ]2 X
8 B  r# T( ]& T: a$ @9 V  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary% }3 ?+ t0 N; x( q) P
  set acceleration 0.099
+ i; D# j2 y, W$ ?end3 ]% V: Q5 s/ d9 i! ?8 |/ l0 i% ~

1 e+ i1 v6 X, T: x' v4 D;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# s  J# b' M# x" ?& D% Y;; and initialize the traffic lights to one setting
, ]2 z2 u; Z, J( ]! ]/ eto setup-patches% @7 D. `& }! O+ A0 A1 o
  ;; initialize the patch-owned variables and color the patches to a base-color: p% J! z0 o9 ]7 Q4 g* z  ^
  ask patches: V3 f+ }* \- Y/ h( V' c" l+ l
  [
7 m# \# [1 r# p/ ^" C    set intersection? false( I  P8 ]1 K9 F/ @
    set auto? false
% s% Z! D8 E+ ~; Z/ z/ z    set green-light-up? true9 h. F4 S6 |2 ?3 x( i
    set my-row -1
& h) c- M5 E3 Z& U( x8 }    set my-column -1+ G9 C2 j& B0 I& x# `1 K
    set my-phase -1
4 I8 t7 \7 @) f7 `    set pcolor brown + 3' o/ y, ?8 |/ i% A% ~
  ]" o3 Z0 Y$ ~3 e3 C- a( w( y

0 S3 Z2 I' e7 ~& |# O( G& r  ;; initialize the global variables that hold patch agentsets
! h# |* |  G1 v& H  S  set roads patches with; Q) u2 P; l, \0 d5 e) ]
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) ]3 o1 P; M0 |3 l' h/ w7 U* S    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% ]- E/ g' e, f; `# H" K; b  set intersections roads with
8 M* ^$ f7 a, n; ?2 l6 R. V    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
/ n) e+ b# y9 ]/ _& F    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 ~4 l7 v4 I6 }3 P
0 w/ @/ U4 n& R& l3 f" B9 e2 R
  ask roads [ set pcolor white ]
' e& h# a, `* ?; [. Y    setup-intersections$ G3 Q0 Q+ m8 o
end& _, W* J% n3 D8 p
其中定义道路的句子,如下所示,是什么意思啊?
- _$ l% U, @" r5 v set roads patches with2 ^2 ]" Q+ Z1 A2 E
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 z( o, S1 Y! o. P) O; l7 @    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], @1 x7 c7 y$ s5 b7 K/ V' Z3 w
谁能帮我解释一下[(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0)是什么意思吗?
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