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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。
- c( q6 P- f& O  I1 Rnetlogo自带的social science--traffic grid这一例子当中,
# e  Q9 _& U  q' g! d, Oglobals
/ W! N* F$ w7 N, X, I[
" O! L& z8 Q$ P1 q* ?5 R  grid-x-inc               ;; the amount of patches in between two roads in the x direction
7 N. H4 T  _' F8 [* E  grid-y-inc               ;; the amount of patches in between two roads in the y direction0 o$ Y$ [# l2 N/ j1 B
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 m6 }2 t$ S1 ^
                           ;; it is to accelerate or decelerate
6 B$ B' n9 {- m3 g! ^  phase                    ;; keeps track of the phase
4 T( l' j% h$ d  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure4 Y( a5 A+ t3 P/ t+ M$ y
  current-light            ;; the currently selected light3 x4 o! X0 O* G3 @; V4 R1 D$ B9 @
9 F1 ~* P" Y3 {# L7 O) y
  ;; patch agentsets+ \8 ^' j. |4 g/ ]; Y; ~
  intersections ;; agentset containing the patches that are intersections  ~' F: D6 j( O* s3 J  {2 S* P
  roads         ;; agentset containing the patches that are roads
' j+ W5 s* _/ a" I]
5 s0 y( u. C: u2 Q: s7 E
; z6 {/ E* \3 k4 qturtles-own7 H( r. S7 P% `% ^! C2 r. b
[
& Q( Y+ }/ ^% |: s: V$ R  speed     ;; the speed of the turtle8 F% D/ m; e+ G. T2 e2 F6 P) Z
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
  v8 u& h* h, E9 j1 {  wait-time ;; the amount of time since the last time a turtle has moved
! m; A4 L4 q, h2 X]0 D7 ~' z4 x% s& I
+ y3 D) J5 u4 c  L! ~3 i2 u: C
patches-own4 z$ R0 l* m  r! X5 H1 r
[
9 s: B" t% z, `3 M& m  intersection?   ;; true if the patch is at the intersection of two roads" m& z) C8 \# L0 `! r
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.7 \7 w: ]. X. w+ a" o5 `
                  ;; false for a non-intersection patches.
# c/ T8 u& I5 X& Z( n/ F  my-row          ;; the row of the intersection counting from the upper left corner of the" u3 {: b' C: H* z3 k) d' f/ ^
                  ;; world.  -1 for non-intersection patches.1 G! i# Z+ V- ~1 {8 c
  my-column       ;; the column of the intersection counting from the upper left corner of the6 q5 T- r2 l4 Y! |: x+ b
                  ;; world.  -1 for non-intersection patches.3 ?5 r! {+ ?/ A* x0 T
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
: R& R9 A/ \8 k8 I2 T8 N( d* Z  auto?           ;; whether or not this intersection will switch automatically.) v& o5 a# a% I2 a1 D
                  ;; false for non-intersection patches.
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8 `( N% Q, y& G$ i, B% T# _2 W8 ^; Q: x! l' o
;;;;;;;;;;;;;;;;;;;;;;" u( L- T1 T% C
;; Setup Procedures ;;
% V2 ~4 T' J. Z' m+ n% l3 x2 y;;;;;;;;;;;;;;;;;;;;;;: ^( j4 i& X0 x& [
6 p( d4 r% k" W% `
;; Initialize the display by giving the global and patch variables initial values.) ^/ v) z; _0 i$ H
;; Create num-cars of turtles if there are enough road patches for one turtle to8 k9 R6 q/ w& p5 o
;; be created per road patch. Set up the plots.5 A8 @: ]( [, \% O- X
to setup
$ W! r1 {& `7 }) m$ a. ~  ca
% |; e$ ]$ V+ s4 G/ M  setup-globals$ [  X0 g, B! u/ ^8 x
' o* k7 D& j& k4 m9 c& Z2 F' j- I# Z
  ;; First we ask the patches to draw themselves and set up a few variables
2 Y" ]* Y$ U, N* F3 Z+ j- D  setup-patches& `- U1 w. W" X' A% k  X
  make-current one-of intersections3 e4 g' s2 H& m8 n
  label-current
7 K1 K- B& A9 q0 x/ ~9 C* C: i0 s
  set-default-shape turtles "car"
9 ]1 {) T, _. e4 s% ^
- [" A- j* J& m" _  if (num-cars > count roads)
' ^! o- e) F9 |8 {1 j" A1 R  [
+ W" N9 s( C+ T% E8 a    user-message (word "There are too many cars for the amount of "
+ l9 [$ V- T0 o, X* F5 b5 Q                       "road.  Either increase the amount of roads "
) k3 |# |" H4 O! e) ^8 W3 F                       "by increasing the GRID-SIZE-X or "/ p0 b5 f% H; J. [& N
                       "GRID-SIZE-Y sliders, or decrease the "' s* Q9 S& b! {# Z9 C# a
                       "number of cars by lowering the NUMBER slider.\n"
* k# G. T  C2 D! w: h$ E                       "The setup has stopped.")# R# K) F1 P. }% K9 ^/ g
    stop
" t( M' Y* I7 h) ^; G  ]# F' p  W( }! M" A$ y; d
8 ~/ p1 w2 Y, {- u' f0 r9 S
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color$ C# o# ]- \6 P
  crt num-cars5 X- i& p' S  {( H
  [
" a* g) g# w/ R- u) _9 d! J    setup-cars
1 S9 k" x' j. E) i# e, w8 C5 l    set-car-color3 P& e- ~( N. ^  B" V' ?  M
    record-data
3 }( K8 c9 E2 V  ]1 F5 F" ]! E9 b1 b" w
1 C4 w9 A; a: r: }3 z8 v1 x$ @
  ;; give the turtles an initial speed! @3 S* E8 ^5 s/ A' X  X6 M
  ask turtles [ set-car-speed ]
1 s& [$ e& u# m4 y" S. z% g0 W- Q3 b1 f3 G
  reset-ticks
' \5 Y1 `. ]3 P9 {  B" ~# `$ Y2 b, m. vend
- `* w: X" \: c9 g, L
, F# ], [! e5 N, y. ~;; Initialize the global variables to appropriate values
9 U8 f" D( ~" Qto setup-globals4 p: M5 i6 X  A+ B& X
  set current-light nobody ;; just for now, since there are no lights yet
: X% i- \2 Y8 s' e4 }9 y2 j2 d  set phase 0
/ e1 w3 e9 x/ x3 J+ A$ E; o0 N# }; f  set num-cars-stopped 0
2 E7 V, w% G6 n  set grid-x-inc world-width / grid-size-x; H5 Z/ v2 A8 Z0 [- J( w
  set grid-y-inc world-height / grid-size-y
$ [' Z3 a2 L8 @# W* C, t+ B! |/ @$ @) M! X& h. u6 u
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary' p: Q  H1 C9 `5 l, \1 W5 U4 D6 v
  set acceleration 0.099/ @1 N+ E' f, f9 i5 k8 o' z
end8 Z5 t) W: d" e2 j3 {& e
: d# \' r4 H0 R/ ?! D8 z& B
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
, n+ b: f# Q. V6 n& I1 v;; and initialize the traffic lights to one setting
9 b" g+ J4 W8 Z. O; j! P% Q- t7 Gto setup-patches1 ]- B  ^# F* E0 [. g
  ;; initialize the patch-owned variables and color the patches to a base-color
2 k, w5 ]* z( j- [  ask patches! P( L& U* H/ H+ t  i. D( N# J
  [% ?) r3 h4 s$ f/ o
    set intersection? false# s! j# U( ]* O& m! t: I, R
    set auto? false, a3 |8 C1 t) g: P' T  C/ w" s
    set green-light-up? true/ q4 d( s" \# M  G% g: n' s) f
    set my-row -1
3 I+ g1 [- @. `* @5 S    set my-column -1
6 e2 O+ m6 u6 N+ d# y; ?5 w    set my-phase -1
' y/ n! T0 w9 E% c    set pcolor brown + 3
6 o+ s7 m9 F* N, T. p  f, v  ]
  [" _' L, y+ n& b+ L: T3 ]2 L$ k3 T+ g: M3 C) R* F9 O
  ;; initialize the global variables that hold patch agentsets
: a9 l; u4 o) j; |- Z; s  set roads patches with
; R4 k6 W! {# n1 i$ w    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 F( I5 }8 O/ X. o  ?/ R
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' ?; C; }2 I8 T2 u: U3 a  set intersections roads with7 V9 C3 @2 E4 v& v
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
6 c8 u1 j" H, z& J3 k# G( c    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% Y9 ]5 u" f0 G2 I3 ?; `6 K/ n
. K0 L- `. F$ g0 L  w/ G
  ask roads [ set pcolor white ]" \! w  V1 n/ v
    setup-intersections
9 O2 ~0 E" v$ ?5 x) Z1 E# B2 Xend
2 _: K2 I4 U* z8 Q' Q其中定义道路的句子,如下所示,是什么意思啊?
3 j, X! D. j4 f. } set roads patches with- S4 c. B6 u2 o; s3 B8 C
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% G; J1 K* K* L6 p
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ k# n. q6 N9 d% ^/ D# d5 ]
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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