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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。9 S9 k6 l0 L; d+ p+ r
netlogo自带的social science--traffic grid这一例子当中,
% y& z. T" x7 S: v! ^globals
! Q* y% B; F3 V0 {[' D& K7 u! j- H9 K, C9 B
  grid-x-inc               ;; the amount of patches in between two roads in the x direction# d- `' I+ u: g5 B* U
  grid-y-inc               ;; the amount of patches in between two roads in the y direction# p& c# b  L# w% V* O8 ?% ^; \
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
0 ]8 A( w* \4 N0 R                           ;; it is to accelerate or decelerate( F2 K! ^5 T4 j# O7 n8 _% u
  phase                    ;; keeps track of the phase
- f2 r; ]/ K4 \5 g  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure, Y. a$ z# a0 X0 @3 Y
  current-light            ;; the currently selected light
4 Q6 C) K. k# F4 C$ @
6 Q9 Y; C/ {: ~( F& O. l1 a  [) C  ;; patch agentsets, k- A, z3 a9 C. ?* ]# U
  intersections ;; agentset containing the patches that are intersections9 w; }, o/ n4 {' _  {/ y
  roads         ;; agentset containing the patches that are roads- }- p1 D1 x: w+ y) F
]/ C5 k1 E/ V( F/ @/ f
. e" Q" q4 F1 N& a' L
turtles-own+ S2 ^% D. ], q2 y1 c& n4 y
[2 o2 ~2 I1 \2 K" X  I* H0 D5 O
  speed     ;; the speed of the turtle
, P. o; n3 r+ G, b+ w6 D) v9 |  up-car?   ;; true if the turtle moves downwards and false if it moves to the right+ m& T3 T! V) x( g
  wait-time ;; the amount of time since the last time a turtle has moved0 c6 Y( {0 I( P+ s% |" }5 b
]' c" a4 J8 M2 A; V$ q
7 t; w4 v/ e0 w! t* o& T
patches-own& C7 n3 l7 v; ~$ N1 Z( r  y# J
[
2 _$ S* x. D9 W% z- a2 [  intersection?   ;; true if the patch is at the intersection of two roads
! L+ a2 E' O8 M* j( F  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
4 D- s% [9 [4 Z* c5 y+ n: ?" r  J                  ;; false for a non-intersection patches.
, q! `8 J6 i% I  W! w# K! O  my-row          ;; the row of the intersection counting from the upper left corner of the
# z3 s5 W9 A1 u$ ~                  ;; world.  -1 for non-intersection patches.
. k9 A) c( |2 B6 l  my-column       ;; the column of the intersection counting from the upper left corner of the3 O; O8 c, ?" x$ ?
                  ;; world.  -1 for non-intersection patches.( R; H, l: u% u: |' K9 L: `
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
6 m$ X" Y# _* g6 e" f. m& ^  k3 k# V3 r  auto?           ;; whether or not this intersection will switch automatically.
+ k' d  J- @: D6 f                  ;; false for non-intersection patches." @, T( q7 Z4 l, j  S$ r
]/ v6 n% D3 a& f3 `6 _

- i. Y4 g; W  z1 U9 U( w! @1 `0 [' j8 z
;;;;;;;;;;;;;;;;;;;;;;
: o$ s$ _1 }3 B) \;; Setup Procedures ;;& j9 w- P% ^: v$ X
;;;;;;;;;;;;;;;;;;;;;;
4 p5 Q1 x' d) {1 p9 q; h* t$ x5 a; A, {# _; _: F0 O/ o
;; Initialize the display by giving the global and patch variables initial values.
) w* v7 t  Y7 a" C' d4 h8 u+ a* H;; Create num-cars of turtles if there are enough road patches for one turtle to0 g$ R! f& T6 T7 y) ?6 @% d
;; be created per road patch. Set up the plots.0 m2 p0 Y: d9 I% u
to setup
% I( R, k8 H) C- ?, `$ @  ca
; q) R# h: b# M2 ?  setup-globals* ]4 |6 m" `: f  O+ ~4 n( C
$ H1 R# X, V8 o2 c& P& H7 L5 @; }
  ;; First we ask the patches to draw themselves and set up a few variables
" t+ ?0 V' s5 o' v2 |  setup-patches
& T) M& e) U% F: l% Z  make-current one-of intersections& @" o- b2 v0 r- m4 j% k
  label-current
, X. j; b' D5 a# D# D
! W) h% H9 X( {, ?! W  set-default-shape turtles "car"
8 Z6 _: u2 s' c4 i3 E/ L+ ?9 y
3 O& d! y* A4 [0 J  J. v" X4 }  if (num-cars > count roads)
" _' t- C6 [. |$ Z  [
- l6 m! ~' G6 f5 u' S- v1 W    user-message (word "There are too many cars for the amount of "
$ ]+ x9 t5 i: h4 k$ n& a( W' B, e; G$ C                       "road.  Either increase the amount of roads "
2 Y' c3 I( b8 ]8 {5 d, B                       "by increasing the GRID-SIZE-X or "
( q, G) i- q! S$ x) O; P! v# n                       "GRID-SIZE-Y sliders, or decrease the "
! r, w' i$ r& V% e6 b                       "number of cars by lowering the NUMBER slider.\n"
% W" N8 i  z: J3 ]                       "The setup has stopped.")9 _; \, {# b# l4 Z! @, f, k& I
    stop( Q* p5 Z4 I$ d- \6 Y* j+ m( r
  ]" S. m  N' g, k0 T/ t# O5 g" x; ?, p
! {. i/ l8 h1 o# n7 \
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
0 t5 A9 k  i( X1 t1 |  crt num-cars2 I0 m2 i6 m! w. {+ n
  [, R9 J: e0 ^. N$ {  U  j8 ^
    setup-cars" _% k7 V+ o! q' O7 ~3 r
    set-car-color
" v; Z5 t8 H2 P    record-data
# a, E3 x' V! `* H8 H; m  ]# o3 F' B8 u" ?1 f

- `) g* w9 Q; c/ z$ d% w  ;; give the turtles an initial speed3 @' f7 v  L$ V/ H
  ask turtles [ set-car-speed ]
% `6 G8 A6 D% K# J0 p) Y) z- R
8 j/ U8 i* K* \: ^% N  reset-ticks
) s4 W+ B+ ?$ S0 R8 `6 m/ D( Hend
4 s! o4 C( `7 W) ^; H2 W2 k- f0 b) K' G3 r1 R6 I! w
;; Initialize the global variables to appropriate values
; {3 j3 y5 \, k$ t9 v- K+ H& _+ dto setup-globals
, ~5 W3 g# e) C0 ]' V3 V- R  set current-light nobody ;; just for now, since there are no lights yet
2 H1 t+ ~; N( Z5 Q4 V, c! {+ ?  set phase 0
- F6 O4 S% |' X  set num-cars-stopped 0
" T8 \4 G' o0 e# x) K. b+ M  set grid-x-inc world-width / grid-size-x
" r" R! g& T1 ~9 v- t# r$ u  set grid-y-inc world-height / grid-size-y% z. o  L4 T! ]: k. z4 V# B7 |

, D' N% L" p9 @) W6 h  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
/ ^* T. d4 }. A/ ?6 M8 _  set acceleration 0.099, p* m% R4 M% g. D$ h/ B2 |! J
end
0 ~( b; w! n. t' x5 F! i. Y1 ]
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,- ^/ z) {7 v/ A% p0 @3 g; `
;; and initialize the traffic lights to one setting
2 y5 ?4 }4 b. e& Y3 \( t4 z; eto setup-patches
/ S! Q2 p: S; Z/ }2 V% |  ;; initialize the patch-owned variables and color the patches to a base-color* T% h+ g5 Z0 k
  ask patches
; T! Y' C8 j' \3 T# |7 K8 S  [
" u" {: c5 D8 X9 j0 C- d8 y    set intersection? false1 s) U) {) u" k/ W0 r/ B
    set auto? false, N$ r8 O7 T" L% [# f! W5 W. ?. w' l) Z
    set green-light-up? true
3 m/ p! f4 }7 _2 M/ ?# C! b' L* m    set my-row -17 G& S) g. y1 u1 \2 Z, k, E
    set my-column -1
1 A- n0 a6 A% q$ r' s# T    set my-phase -1; Z/ }4 J' m+ r0 |0 m5 }& R- a
    set pcolor brown + 3
3 a6 {. n5 P# s5 A, B  ]
: Z- h, B% @2 M7 `2 M0 K" I
7 m" J$ j5 Y6 b  ;; initialize the global variables that hold patch agentsets
: Y' l" \9 F# l* y6 ~  Q" \( G1 }  E  set roads patches with
& a, e$ K/ c) G    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- H' I. ]3 d: J% a) D3 @
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* H" F4 t9 n- J
  set intersections roads with  i- U# Y3 v* q8 |  O, x
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and3 j2 u! a2 @3 d" d8 A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 b4 z5 F/ p& i+ `5 Z, q6 @# A' Q+ z% t' z/ w- O! I+ J( L1 Y5 q
  ask roads [ set pcolor white ]- Q8 [0 h* ]7 g2 d& Y) I
    setup-intersections. |) ?/ u! B8 E+ o
end
) T8 |2 _" Z$ ]9 i: O/ H其中定义道路的句子,如下所示,是什么意思啊?  b- l7 f/ [1 o6 P" ~
set roads patches with
- J0 H) c  s( ]4 X: c    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 x3 L/ c: v, q, ?  T1 j' r    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" J5 t) m, t8 r+ C; O& Y
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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