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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。
! T) E9 b( Y/ C" s* f& enetlogo自带的social science--traffic grid这一例子当中,3 [. O: T0 G& I; b2 m
globals9 w6 Y* N% k, L* E# w# f& S
[4 _! u, F! q. |9 i2 ]
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
. V# F3 h% B5 L# A1 y  grid-y-inc               ;; the amount of patches in between two roads in the y direction
& @4 j! ?' Y6 r$ f. D7 P  acceleration             ;; the constant that controls how much a car speeds up or slows down by if8 h5 u  B5 w5 L. `$ }1 f5 O5 q
                           ;; it is to accelerate or decelerate" y3 ]8 d8 E& }7 W  g" s* I
  phase                    ;; keeps track of the phase. ^' e- @5 P7 f8 q8 t8 B/ l
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
9 f  g* C  M% e  t" Q) _  current-light            ;; the currently selected light
" o2 A7 e; a0 Y) _
$ J* G+ b3 V3 j, m' l( [  C  ;; patch agentsets
7 S7 v$ I" d; U! n  intersections ;; agentset containing the patches that are intersections' c; m! N4 S. r: v) r2 j) h2 v
  roads         ;; agentset containing the patches that are roads
& b* d6 z) J/ ~* s7 H* E/ S]
/ |% J$ @' D$ [) V4 w' f# K
! I" a, a$ Y+ Rturtles-own, |) }8 [1 K: y% O8 a: N* ?
[! i! w( N$ A/ F% ]6 G! v% {: w
  speed     ;; the speed of the turtle
$ o0 M" R4 O: y* j7 Q  x  up-car?   ;; true if the turtle moves downwards and false if it moves to the right8 v% Q2 w* Y7 P: N  L
  wait-time ;; the amount of time since the last time a turtle has moved. Z# b; s: I2 [* t" W9 k- [5 S
]
5 k9 s' b1 f+ k  I. b1 Q6 i% e4 m4 b$ d- y5 U9 u
patches-own
" V' w8 p# b- e. w" V[9 ~5 K4 h4 H* `  C
  intersection?   ;; true if the patch is at the intersection of two roads( X; f! @& X' x1 D
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
; ~1 D6 Q: p- C+ }/ `& K3 R' k  U                  ;; false for a non-intersection patches.
! [0 p) Q5 c, Z  my-row          ;; the row of the intersection counting from the upper left corner of the% I: W  g8 H# I) l! V. J  Z% o
                  ;; world.  -1 for non-intersection patches.
$ I: b7 r7 f4 V: I! F/ A  my-column       ;; the column of the intersection counting from the upper left corner of the! [, }& j, v3 E1 P- X
                  ;; world.  -1 for non-intersection patches.
8 m8 i' m0 h7 y: Q5 [  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
5 |) I, n0 ?3 B4 w  auto?           ;; whether or not this intersection will switch automatically.
" l, o, x% b: l$ v7 T& `7 C                  ;; false for non-intersection patches.
+ K8 c9 `; F4 d. Z/ S. U( Y]
& Z* p' B3 t: x/ [) l/ X5 n, s
* R! ?& t' S9 D; b- i( w; b- o& {, v8 J2 g7 a5 ]1 D) O
;;;;;;;;;;;;;;;;;;;;;;
, t6 b& t! I- l;; Setup Procedures ;;# g7 d6 k& g0 Q* \
;;;;;;;;;;;;;;;;;;;;;;
) @8 c! Y. @* S* q+ \9 a* [
: M, G- Z# N; ]5 q; k;; Initialize the display by giving the global and patch variables initial values.+ r2 V9 L# Y  u- \4 L
;; Create num-cars of turtles if there are enough road patches for one turtle to
' d0 q$ o# i- b& b5 v7 |6 D6 u4 @) \;; be created per road patch. Set up the plots.
' t2 |+ Z. c% H* g) \5 Wto setup9 ^/ y) c9 r9 q1 a
  ca1 U# f3 H% o: w9 |8 m. s, I
  setup-globals; S' K* G+ `) z7 u; \. @3 t1 C

2 _$ I; n8 l$ j- s/ ~" Q+ k7 D  ;; First we ask the patches to draw themselves and set up a few variables( }0 R: D" H* d# r# q7 I, @
  setup-patches, _7 Z% i" l9 h( ]
  make-current one-of intersections% h6 E) K( Y/ r3 q% w8 \- e2 L8 v8 ^
  label-current2 u, h$ G4 H- R; l  y& P
8 u! Q6 `# P. c5 H! n: K
  set-default-shape turtles "car"
9 y$ k6 M) j! v! d! }. f- [2 E( l
  if (num-cars > count roads)( W0 a' U$ c6 a# X$ W3 x* @
  [# B! u$ G# ]9 F2 p. w3 M2 x
    user-message (word "There are too many cars for the amount of "
- @3 K1 Z6 t# n# ~                       "road.  Either increase the amount of roads "( _% _5 e) Y2 f3 L2 y
                       "by increasing the GRID-SIZE-X or "
" C" `0 q  R. L  Q( \                       "GRID-SIZE-Y sliders, or decrease the "
1 [" D& F' h# I% j: B                       "number of cars by lowering the NUMBER slider.\n"1 J! `6 g: O: W7 j) }. b* T
                       "The setup has stopped.")! z2 ?! f6 z: z! L
    stop7 B) z4 @1 w- x2 Q8 U9 T
  ]$ _& \8 A, o# D" Z( Q0 K

8 f: n  M* f9 r) G- m% w  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color- O4 ~, O& W- }0 o
  crt num-cars
( E/ D& v, f3 ?3 t  [1 B  Y! f) O* X( H+ A
    setup-cars
4 ?# I$ I9 a4 L) u5 V8 w* ]7 b    set-car-color
) J) q. ]8 ]  d" |: n8 p. }    record-data
1 e7 w9 [/ D5 e+ k  ], G7 [7 R0 Z3 x, i
! ^3 d2 Q0 ?' V/ y( P
  ;; give the turtles an initial speed( @) J. A! N& p; G/ Q
  ask turtles [ set-car-speed ]
! B+ T2 R6 i$ O, K! W" I/ m2 Z$ M( Y) Q* R5 J
  reset-ticks4 m$ t7 i9 b- Z* G. _5 k2 i
end
$ n* i% z- S6 @5 k5 ^) [: k1 G6 U2 H  z4 q4 f0 f. V
;; Initialize the global variables to appropriate values
6 ~3 _) N( ^) |& q/ wto setup-globals* \1 g+ B2 g- Z& o+ q5 d
  set current-light nobody ;; just for now, since there are no lights yet* c$ U6 ]" ?+ N
  set phase 0
) y) k, z+ l' W+ l! K8 B# t& _" s  set num-cars-stopped 0
/ ]; d  K% h$ G  set grid-x-inc world-width / grid-size-x8 j7 B+ P( z/ b5 [
  set grid-y-inc world-height / grid-size-y
. @0 u, c. f6 {( l9 ~
' _1 q5 p: \# H1 o  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary# B$ @8 ^) K* \
  set acceleration 0.099( h' g' O) k% T( F6 X
end
  @/ o  a" {" L4 D/ w5 F2 d9 N
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,+ L0 n+ }: ]' B& H1 `
;; and initialize the traffic lights to one setting9 M& N8 U6 f4 D
to setup-patches
5 L+ L7 H2 g7 M* u! M1 e  ;; initialize the patch-owned variables and color the patches to a base-color7 q4 x9 d/ [2 f0 ]3 `& t# b
  ask patches
. A# u3 |9 U8 a. j4 ~  [& X( M8 [+ k! z' `! S/ h
    set intersection? false7 b3 z! P5 i* Q- v$ P1 ^
    set auto? false. u$ I$ C" z2 n
    set green-light-up? true, x6 U3 P5 X8 i( {. Y
    set my-row -13 H; n2 M; C, @, H# w
    set my-column -1
- g  ^. P' Y/ a. t0 X    set my-phase -1
/ E; i( |: R5 N6 {# s: l    set pcolor brown + 3
* [/ f7 ~! @, r  ]
( j/ X4 Z, M  _" b
. M& V2 y* [6 r8 l* i* I/ f: Z  ;; initialize the global variables that hold patch agentsets7 M0 V9 q5 u% z3 K( k  ]0 K; j
  set roads patches with
9 K9 q1 K: ^0 C' r+ P( T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( ]! l- b6 n1 X" ^" V
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! s. N. V% K3 b; U
  set intersections roads with
, \# d9 k& T! d    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
' C' c* o; r& H. \: R$ B& K    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 C8 @1 e9 ~% D% {5 p8 N5 O

( m. C0 O3 a" R7 [  ask roads [ set pcolor white ]
: ]& ?8 W6 v8 ]6 K# K    setup-intersections4 l, v: E* Q, Y/ y, q8 \* I& X4 z/ n
end
8 B) k- v+ w- w- W; ?其中定义道路的句子,如下所示,是什么意思啊?  {  P! c1 M6 h# p% l
set roads patches with
& m! H1 Q. D. `; O    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% \$ H+ p4 J3 V" \# J    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 A* D3 `# j. T% `8 t" U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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