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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 [. V0 }% `& v6 E9 O. P! m
netlogo自带的social science--traffic grid这一例子当中,2 a# A$ j2 q, {% m
globals
4 y" Y# M5 `3 E, U# o! o) g6 ~2 g[
3 N- L7 b( E" @0 E  grid-x-inc               ;; the amount of patches in between two roads in the x direction% {" d* y# R5 N  ]
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
& T  U4 A/ o% E# O  M  X5 v+ b  acceleration             ;; the constant that controls how much a car speeds up or slows down by if. y& d' q; _2 o
                           ;; it is to accelerate or decelerate
4 Y* {+ O. a, Y9 }: m  phase                    ;; keeps track of the phase% h3 O5 Q, p- b0 y
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure4 R$ e$ o+ U  s3 o! w9 \
  current-light            ;; the currently selected light
# q$ o4 E) j2 G1 H) N3 @1 @6 E0 z7 a* ^. |- \. d+ x, a2 K' t  J+ c3 ^
  ;; patch agentsets- r. H( M# C6 k( A4 g0 g4 _6 R
  intersections ;; agentset containing the patches that are intersections* g3 ?) T( ]7 @) `1 c; f0 ~
  roads         ;; agentset containing the patches that are roads7 W% K2 g! ], O5 a) p5 p( ^) {
]' F+ \8 p! T9 Z9 m% Z# [8 d$ h+ p
  o- o; H7 r* L& G* W
turtles-own
/ n0 U1 A0 F+ y) h2 z5 s6 F, A) z[  ?9 i8 E  E9 W7 e$ W
  speed     ;; the speed of the turtle& m' D5 \1 E' J5 w
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
7 w7 ]( N/ Q  s& H0 ~  wait-time ;; the amount of time since the last time a turtle has moved8 I( Y) x. \* D% k6 x9 R! H# l
]4 W0 g% M4 S0 d  z- l5 \
6 r5 \9 r# e7 \2 W3 U/ z! r
patches-own" y; }; |1 \5 l$ Q8 g: v  i0 H
[* t5 r  s2 ?6 g# R. G  v
  intersection?   ;; true if the patch is at the intersection of two roads
+ ^3 }  g2 X6 C+ M# G  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
1 s0 J7 c4 m) O) P. e: ?                  ;; false for a non-intersection patches.
( _* l) y4 ]$ F* h  my-row          ;; the row of the intersection counting from the upper left corner of the
+ q# @" F, R- v: d8 e                  ;; world.  -1 for non-intersection patches.
4 x* X. @  s; L# {  my-column       ;; the column of the intersection counting from the upper left corner of the
" g, g: k% C- z3 m2 i( c) q# n; Z; U                  ;; world.  -1 for non-intersection patches.
- l! A. L9 a5 N/ e  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.6 W+ _! Y/ I' [) M/ p
  auto?           ;; whether or not this intersection will switch automatically.
7 p. x( y, o& s& w% i3 ]  R                  ;; false for non-intersection patches.& S2 H7 M8 B4 W7 C
]
/ T& G! W2 u0 W' p1 K: |7 m4 m1 Z$ O# [* C
, q2 W2 \3 v9 D# k& T6 I4 j
;;;;;;;;;;;;;;;;;;;;;;
( P/ L4 P! K8 m0 Z  K2 R;; Setup Procedures ;;
1 c' Y" x% S6 V# ?5 D$ Z, x;;;;;;;;;;;;;;;;;;;;;;! H' M+ j8 i2 ^8 W
$ B' }6 L; s- J0 e: f" o) t1 R
;; Initialize the display by giving the global and patch variables initial values.
1 a" x. i+ }# U( |8 T5 F;; Create num-cars of turtles if there are enough road patches for one turtle to3 A2 X  s! k0 V6 Q/ t  q
;; be created per road patch. Set up the plots.
. f# S. ~; c, i$ @  C( \# T. zto setup
, ?  q1 L5 I$ R/ O  ca+ N* t. b6 ?  c5 ~, D# B  R
  setup-globals
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3 E# ], h/ g3 |/ t8 z  ;; First we ask the patches to draw themselves and set up a few variables
2 }0 Q/ d$ }# d2 Z% W2 `  setup-patches
" {* |; T) C% R" i- G% K) R  make-current one-of intersections
! X4 O, A1 f7 z  label-current
5 E$ B" C6 R3 L% |- {3 y% N! A
  set-default-shape turtles "car"8 X3 X, Z0 c7 m" A) u- [
% {  _# ?+ H; |- z8 K
  if (num-cars > count roads)
' T" P+ E1 a( N1 {6 {  [7 u$ F, I, k& F( K8 }7 X
    user-message (word "There are too many cars for the amount of "
5 b( p( n8 e! p) ~! p                       "road.  Either increase the amount of roads "$ ?4 b3 v8 k( D' n- c7 A* S4 l
                       "by increasing the GRID-SIZE-X or "8 `* `. v+ \- O0 A( X2 g
                       "GRID-SIZE-Y sliders, or decrease the "% U+ H# d0 i5 p
                       "number of cars by lowering the NUMBER slider.\n"
! |1 f" y. I" d# n! c. i                       "The setup has stopped.")
, H- ~3 I7 N: \* S/ ?    stop3 N9 I5 s0 j0 n% C  z
  ]
7 ~; i9 l" E. C1 C0 V; I/ q4 x
- I8 M/ Y/ Y, f  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
2 J' i( A& U& N. Z  crt num-cars  h7 ]/ O$ ~9 b- v
  [
( G3 e. N3 W( n. m6 Z3 S1 v    setup-cars" C* q7 z4 Z& q
    set-car-color
# ?, Z5 X/ X; D2 w$ a  W, c9 N* H" M, K- A    record-data
8 V3 H5 F* _  Z/ T  ]% F6 `  q- d: ?7 c1 r% J9 @

5 I& i4 Y5 f- [1 u& ^; R2 L) J  ;; give the turtles an initial speed
$ |: H. x. q- C* {  ask turtles [ set-car-speed ]2 G6 V2 p) M3 C

& c! w: B. L7 G  reset-ticks
1 ^; n, m* _5 j9 w" R/ }1 Lend
- p5 p& y+ I+ a: R& H; e/ H, X/ A# K
;; Initialize the global variables to appropriate values
& X2 X8 s! Z% Ato setup-globals/ c) j+ o4 L: \5 f
  set current-light nobody ;; just for now, since there are no lights yet
  {' C1 _8 J% `  set phase 0
# g* s7 ^* ~0 l% B  set num-cars-stopped 0
7 i$ H& K, a4 t5 i  set grid-x-inc world-width / grid-size-x% r$ \" u. V+ c+ Q$ ]- G
  set grid-y-inc world-height / grid-size-y- |8 H2 L6 S* A; j4 t; c) {3 Y
& r5 f, r* p8 F, T% j0 u% K
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
6 Y1 E' M  T  q4 K, z# h  set acceleration 0.099
: g4 y& W; M0 ?9 X7 q5 E8 yend# e+ n9 Z# N+ p; |; y! K- T

! P4 m  H2 k/ K( f! [7 W4 o/ d;; Make the patches have appropriate colors, set up the roads and intersections agentsets,* |; z' A+ L* k) \8 L4 h& C
;; and initialize the traffic lights to one setting, z: e# z, i# E5 P  ]) S/ _
to setup-patches
; U  C; b/ E2 D0 f7 S- z  ;; initialize the patch-owned variables and color the patches to a base-color' [8 x' A# z( T9 ~
  ask patches1 e, J% L5 |" F2 L
  [
, l- u3 E/ Y* N4 I8 T. Z    set intersection? false
4 |, _8 e/ |# ]5 K8 N1 a, X5 Z4 X    set auto? false% Z+ A- V7 ]  Z* r3 h& E
    set green-light-up? true
0 C: {% N% _* @( D& l    set my-row -1, L  \6 }) p5 C+ `: x8 P8 W- k
    set my-column -1
2 m$ H1 ^4 }: `    set my-phase -1
. J" `2 z  G: v    set pcolor brown + 3
5 X& ~% D4 P  H' h8 Q+ {  ]
  k( f5 Z& E9 x; a  ^, `; s7 X" n% H& g9 E4 [
  ;; initialize the global variables that hold patch agentsets* w' H: h# _3 w9 d+ S) e
  set roads patches with
& o6 h2 r7 d: Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ m& U1 y% |, ]5 M8 N4 X" L3 |3 ]
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ O4 _' K  ?( l. ~+ }  Y. I* y  set intersections roads with
1 H) k; J- t; V: n) T% G% `+ L    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and5 G8 a) {, T9 g9 ^. u& u# C+ b$ [, L% r& b
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 K9 h/ o$ }0 K0 k# r  r! H. u0 ~6 G+ _  @4 x
  ask roads [ set pcolor white ]! l5 Y7 I$ _# f
    setup-intersections
0 Z: `4 m2 T- Q6 g- send
( `/ _: F, e; N# t2 p其中定义道路的句子,如下所示,是什么意思啊?
0 Z+ d% P1 A" p- I$ V0 R- q set roads patches with0 F! O' l9 h2 S& |6 P+ }
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 E, ~/ ~  [4 b$ }1 O9 o- ?% n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; n  R  L! F: @) f. X. ]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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