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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。' i) k9 l1 |4 h
netlogo自带的social science--traffic grid这一例子当中,
1 O7 ~3 p4 r- V0 Z+ z) pglobals
) E/ A3 P: D- [5 l- B$ K+ n6 U  w[
7 }. j5 q/ r  u  s! O$ O3 a" _  grid-x-inc               ;; the amount of patches in between two roads in the x direction- g- v% r6 M; J% P- Z* c. N3 y' a
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
: h) w4 U* F3 E1 e7 W% P  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
0 u9 I/ P$ g1 A  x# [' j" E                           ;; it is to accelerate or decelerate
) k2 K7 N8 |: T  phase                    ;; keeps track of the phase
) K4 I: F7 `1 w$ V) z  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure& r# c. N, z$ x7 p. }" k
  current-light            ;; the currently selected light
6 |) X3 S9 m: ]
$ I; s" z+ _0 x; V$ K" a: V% Z2 m! p  ;; patch agentsets
; z% @8 D2 R5 H7 b7 S: E5 O/ T4 N  intersections ;; agentset containing the patches that are intersections8 l$ O. r1 L) @1 E9 w
  roads         ;; agentset containing the patches that are roads% E. b+ t2 R" R" ]9 \4 H$ \) L; G( C
]
5 d  J- v+ Z& N5 C0 v7 g4 H5 l6 l$ U* V1 ?
turtles-own
. c2 H$ ?0 Z7 |; Y' M[
/ y5 q4 Z8 N, b- c  speed     ;; the speed of the turtle
  \4 Q' @' |; M, {  up-car?   ;; true if the turtle moves downwards and false if it moves to the right! b" D% u0 |4 f
  wait-time ;; the amount of time since the last time a turtle has moved, v5 a0 L1 E2 d" x1 n
]0 Y' a2 q6 y4 O5 n/ \: j
: l5 ~5 X: o8 C+ K0 f) t( ^# @
patches-own. b% x2 A* C) k, h8 ]' J4 I
[- I' D4 c3 F- I5 e
  intersection?   ;; true if the patch is at the intersection of two roads  f4 H6 H: j0 u  o. `% K
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.$ j* v1 |4 Q1 d( Y$ ?# v
                  ;; false for a non-intersection patches." ^0 [( e, B& a& m2 F
  my-row          ;; the row of the intersection counting from the upper left corner of the
: e' s8 ?3 z# ?' b0 \                  ;; world.  -1 for non-intersection patches.9 ^& g9 Z6 V) a) j8 f6 p
  my-column       ;; the column of the intersection counting from the upper left corner of the
" E; Z6 n) _% N1 Z$ U                  ;; world.  -1 for non-intersection patches.
( t% O, y4 t4 v, Z+ L5 _  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.0 S* \9 ?7 B$ \/ b& K, ?
  auto?           ;; whether or not this intersection will switch automatically.
3 z7 k% |- Q/ q  M; E                  ;; false for non-intersection patches.9 J3 ^! |  Q2 ~( a$ f0 f
]$ c0 T+ B7 `8 n) B) n" {
# e" s& E/ ^' q3 ?) _+ P. P

* t$ d6 v3 N$ c# s6 X. D;;;;;;;;;;;;;;;;;;;;;;
1 ]" Y/ v1 p) p$ d1 W% C/ ~;; Setup Procedures ;;4 Z: H2 h  V' S. y, R' _# n
;;;;;;;;;;;;;;;;;;;;;;  u# c  l/ d# Q0 S6 E- v* y( Q3 d* i
; h  p4 D% x' O; D" r& X& |7 g
;; Initialize the display by giving the global and patch variables initial values.7 l! y. X2 _# X9 E- G. k& B" m
;; Create num-cars of turtles if there are enough road patches for one turtle to8 n: m3 M, t+ V
;; be created per road patch. Set up the plots.
7 E% j8 i1 K% I4 I( Qto setup) d% `# p2 S  \) P* o6 |
  ca
! A: {( Y7 k  \  setup-globals
8 {* }1 v: V2 q4 F" S$ _0 k  O: ~- ~% K. ~. w2 p+ w
  ;; First we ask the patches to draw themselves and set up a few variables5 W+ i6 e. I0 J. X6 t1 f- F' ~
  setup-patches
; [+ ]2 u# O! l  F' L6 G6 N  T  make-current one-of intersections
+ o0 |( i7 O/ D2 L+ N; z  label-current7 s: b- \. c4 D) b* D

6 W6 c" X$ U, u3 m, F8 _$ J# A6 ]" y  set-default-shape turtles "car"
. |$ ~# c1 {. `9 f4 F. y% {$ c4 i
. g( g/ k! q, e: p0 l. p  if (num-cars > count roads)* g( Y! w5 H6 n  r
  [, g# y4 G. V& o' M
    user-message (word "There are too many cars for the amount of "
, c% i0 ?& u2 {5 X                       "road.  Either increase the amount of roads "
5 m9 Y7 p8 \) V$ M# c8 F( K3 o                       "by increasing the GRID-SIZE-X or "
, ~" k1 e. z; F1 k- }' r                       "GRID-SIZE-Y sliders, or decrease the "# v, k- `0 k+ v3 I) w& P
                       "number of cars by lowering the NUMBER slider.\n". @) X1 O+ q- _) R' O' t$ Q
                       "The setup has stopped."): J% k  y6 i1 n: ?$ h: m
    stop3 s4 U2 y% U( f. x: r4 M* Z) n
  ]
& R0 d1 }( b  Q3 F8 o5 \! p/ x& U9 M- ?
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
- T& R/ s' `* x; M7 s5 C- V  crt num-cars" u1 j* V2 Z  }# l% T  R* `
  [
. p; \/ U6 y4 i" l    setup-cars" E& y6 k1 H' ?! r/ d
    set-car-color
2 s! U- n( A( Z; ^! m  x* \: P    record-data! t8 [5 a5 W( L1 a9 o
  ]
6 [/ e3 B6 \: E8 L) T0 N  d% R" w3 M3 [' ?- o
  ;; give the turtles an initial speed$ s. r6 ?. c% S$ ?, I# \
  ask turtles [ set-car-speed ]  _. C  t5 q6 d) }4 R$ R

4 a" e' H" C! C( ~; U) Z  reset-ticks, O% |1 I5 i3 E. X( H, Y% R4 C
end! N+ Q  |5 l7 w8 p# a

* a9 P1 a8 {0 K% F+ q0 L. ~/ c;; Initialize the global variables to appropriate values
# n4 K4 Z+ V  f2 i% H2 q+ o' ^to setup-globals
8 z- p# C7 }( ?& @  \& R% H2 F  set current-light nobody ;; just for now, since there are no lights yet" C' F% T* P4 K! C0 |
  set phase 0/ O! g0 N2 c, e- r) p$ C
  set num-cars-stopped 0
. Q, Z% l1 y* r4 q5 P- E. }  set grid-x-inc world-width / grid-size-x
- |$ p: I, \" O- i% j/ E- K$ c  set grid-y-inc world-height / grid-size-y8 v& N% W0 _  A$ h$ Q
. `- X) I$ F/ K0 P' G- u
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
4 N, \* z6 K% y  set acceleration 0.0998 K/ L7 v$ R0 \2 D$ L# U
end7 h+ X. W+ Q% J7 E

; A, o/ R4 _! Z6 A;; Make the patches have appropriate colors, set up the roads and intersections agentsets,4 e/ b$ J) h- E4 r- W( ]+ A
;; and initialize the traffic lights to one setting
- `) S& h7 h4 o/ Cto setup-patches1 V  C& P7 `) F- U, X# u9 @3 \7 A" \2 `: T# s
  ;; initialize the patch-owned variables and color the patches to a base-color5 G1 w7 G; B0 ?" w
  ask patches0 q- @, q% j" [0 p) o
  [+ u+ l: V" i# c' d, D# S
    set intersection? false
3 T8 C- b$ Y) k    set auto? false. S. O9 M. Q. t5 v
    set green-light-up? true
0 t4 \; v1 K7 w! b5 Z& j# j; z* J    set my-row -1
( e8 [9 c2 P% P' ~# A    set my-column -13 h/ @: i4 @0 z' h/ p. o9 F* Q1 W
    set my-phase -1
6 j( h8 P. T) T: _8 [: U+ g    set pcolor brown + 3  F# {8 N) r% B( e
  ]
% A( d! g8 \0 _: r
3 v9 ?5 m8 ?! T  l( e6 ~  ;; initialize the global variables that hold patch agentsets
' Z6 V5 |7 J( F6 |% N* ?4 k* n7 z  set roads patches with
( R/ U7 u- y7 z  j0 X    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& W$ }  r$ w/ K" W( n' r    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- u+ H% x7 s/ ]0 ^$ F  set intersections roads with0 _( h. T& d5 Q# t- _$ G+ ^
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and- Y! [  I8 v% }- Q+ a& J# k
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: [. I1 C. c) ]6 U8 ?" a% ~! k! e% M
  ask roads [ set pcolor white ]# ^( c) V& s& Z6 w9 d
    setup-intersections
, W6 P0 u  N% m; r2 ?! xend* k$ n% C% G; C+ r2 z5 d8 K
其中定义道路的句子,如下所示,是什么意思啊?
# {. }! v$ a1 I' b" J set roads patches with2 G6 u" p( f7 T- ]/ Y8 |  f
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 j" T9 {$ R! A) V' d5 c    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 A0 z* V6 E* b
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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