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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 ?& b$ f* Q) e- {$ z& Hnetlogo自带的social science--traffic grid这一例子当中,
# z3 N$ F  A2 ]. c9 ]) ]globals* W$ W, u, Q5 b; I
[- X, W$ T% f" Y, ~8 Q; c( ^
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
" @1 O" |6 x+ h# I( I# s  grid-y-inc               ;; the amount of patches in between two roads in the y direction
* w9 t) e$ ^3 p( d/ V  acceleration             ;; the constant that controls how much a car speeds up or slows down by if1 e5 `; M: \& b, ^9 g
                           ;; it is to accelerate or decelerate- R1 D; u* W% S4 W$ u
  phase                    ;; keeps track of the phase
+ Z7 U  [% o5 ~3 C+ m7 e+ g2 N+ N' Z8 o  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
3 o% O0 @) R  E& i2 n  current-light            ;; the currently selected light
. y9 R8 T' A- H1 C8 t% _) T* W( D4 c0 q+ V
  ;; patch agentsets
0 ^; Y3 m$ p8 A' B6 }) _  intersections ;; agentset containing the patches that are intersections- \$ Q, n% d7 Y# w$ G+ ^
  roads         ;; agentset containing the patches that are roads8 x7 U3 |" F+ j; b- x  r- t
]
2 p- H1 t7 o0 U8 I+ w9 N) K6 V- \" r! X$ B9 ^5 T$ Y: i
turtles-own6 J: _! w2 ~; B4 U4 f
[
. U: @+ K9 g  m/ y  o( W0 O  speed     ;; the speed of the turtle3 @: S& F3 H( H7 ^- z! R0 c
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
& d* ?# z' e/ a" O; P8 l  wait-time ;; the amount of time since the last time a turtle has moved4 h4 C. M8 ^  ?5 }) @
]+ t3 Y7 ~6 }1 f5 S

/ ~( @+ r' N! Y- j% d) A! k0 qpatches-own% `: u' Q$ m, f. d& E! {  l+ }
[: w- ~, M; C% P) [, g0 Q6 i, x: _  |
  intersection?   ;; true if the patch is at the intersection of two roads
2 S5 B" k% P. _0 ^) A8 V  green-light-up? ;; true if the green light is above the intersection.  otherwise, false./ ~5 ~" }! ~, E6 o
                  ;; false for a non-intersection patches.
/ H+ d3 F2 I0 @  my-row          ;; the row of the intersection counting from the upper left corner of the
' m: n0 T' y' u7 h                  ;; world.  -1 for non-intersection patches.  c: P( `9 \1 z7 s0 ?6 f) o
  my-column       ;; the column of the intersection counting from the upper left corner of the
. c3 ]) {* ?9 |) m                  ;; world.  -1 for non-intersection patches.* C2 c2 A) o. Y- h' J
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches./ h1 r4 B& t: h$ X& I, |
  auto?           ;; whether or not this intersection will switch automatically.2 N* j" o; A: g* a
                  ;; false for non-intersection patches./ r. ]  W' I1 O; g
]0 A9 T2 A+ P6 D5 p" l( Z" ~2 _$ D

5 ^" z. z% @* e- L" \0 Y
6 a8 J& @, H1 V;;;;;;;;;;;;;;;;;;;;;;
) v% l" r6 G2 ?2 Z;; Setup Procedures ;;
% @/ v& I; S0 u6 k/ M;;;;;;;;;;;;;;;;;;;;;;
) ]1 h5 j  [) _" c
; Y+ f5 Y, \4 j8 h% [. l3 N;; Initialize the display by giving the global and patch variables initial values.
, ~' M$ r2 M& k% L7 I;; Create num-cars of turtles if there are enough road patches for one turtle to7 W2 r6 }0 Z2 w0 A
;; be created per road patch. Set up the plots.* D7 C! |/ e0 e% y, v8 K& G! x  C
to setup8 [5 X/ ]* o+ P6 u6 z
  ca
; d. X. W  Z  K% d$ y. m2 r  M/ Y/ F  O  setup-globals
. ]5 m% {8 o, r" g3 U! b1 l+ J& T0 v$ t& v: ~, y! c  j
  ;; First we ask the patches to draw themselves and set up a few variables9 g- u& Y* C  e
  setup-patches8 ?6 }/ V8 ~1 Q9 o6 d/ O2 y
  make-current one-of intersections
4 g( O7 U7 S3 x+ I& G- `' R# J  label-current
) }8 d# e+ ?1 H/ l% l% s! K" u5 g0 s# H. @+ _. u
  set-default-shape turtles "car"# S; V: a+ Q# [
5 I0 t, k& E6 H- e3 @& ~3 t8 A
  if (num-cars > count roads)+ |2 L2 y. F7 O% Q0 n: B
  [
/ [4 ^+ l& `: o' A: U    user-message (word "There are too many cars for the amount of "
4 ~4 x# i  W8 N: U5 C) ^& }1 k& v                       "road.  Either increase the amount of roads "
, v( }+ @2 E3 z' t                       "by increasing the GRID-SIZE-X or "1 M+ R3 [  v; B2 p: s
                       "GRID-SIZE-Y sliders, or decrease the "3 A$ d; P% k! X9 i4 h8 h# M' b% R
                       "number of cars by lowering the NUMBER slider.\n"
* ?# j4 N- D6 h: E1 D                       "The setup has stopped.")6 B9 y+ Q: r6 O. _; ]
    stop
; L1 ]$ }# h8 e# M  ]
& f" l7 s9 P: u5 ~- T
2 _/ w# ]; _) O  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color6 `. ]7 E$ J& \  F7 p
  crt num-cars
# H5 h( r# a7 \8 O; q$ F! r  [
: G) ]0 T6 Z; _+ {9 G    setup-cars
5 |" K8 D# h: k. H, Q    set-car-color  ^( e4 Y$ P0 N4 Z
    record-data
5 X# X1 P) |0 Y5 d* }" j  ]: w" U+ z5 g/ [9 H8 U0 e

( e+ k8 C7 S* L( w# T: e6 x7 O  ;; give the turtles an initial speed
) q* w/ I" y9 s) ?: n  ask turtles [ set-car-speed ]
2 `. F8 L. O: r6 v$ E  w. {" K+ b: R7 N# x( k  n
  reset-ticks" T! V/ ]2 R4 Y6 z: s8 u0 `- \
end
7 O" M6 ?( ?' G; D# \
. m4 u" B- ~0 K;; Initialize the global variables to appropriate values5 x& O$ n) F6 k1 v
to setup-globals$ w2 n) L2 @3 b. Q+ N7 _
  set current-light nobody ;; just for now, since there are no lights yet# i5 O+ _2 @) V: A4 c
  set phase 0# K0 a& c; E7 E6 \: h4 V; Q
  set num-cars-stopped 0
/ ~* v2 c; N+ |# l! j3 V; l2 r8 [  set grid-x-inc world-width / grid-size-x" W4 h# C9 b1 s' J' Y6 {4 T
  set grid-y-inc world-height / grid-size-y1 Z  E- U1 @( p, W. I

$ Y/ T# _. A0 c# i- [$ J( h  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
& H3 v" M, F' I& R- |  set acceleration 0.099# h4 I7 D: }* i1 n- g
end; Z0 a$ ?3 ~1 I5 a) g4 q; P

$ O7 f% k- K2 k1 n' a* P5 B;; Make the patches have appropriate colors, set up the roads and intersections agentsets,$ L! \  o: c) U3 N4 `0 a
;; and initialize the traffic lights to one setting
5 m0 a% O! |' o6 R8 dto setup-patches
, D4 E; K" ]- D  ;; initialize the patch-owned variables and color the patches to a base-color2 c3 E8 b: D. B  M8 [' S' _* J
  ask patches9 U9 l# {" N9 G
  [: Q8 O1 _4 u* [# v- l1 [
    set intersection? false3 U5 M% |, V7 W9 J3 B
    set auto? false0 h$ k8 h4 `& e
    set green-light-up? true1 X: }) f) t5 V6 [7 j
    set my-row -1
6 }$ o6 v. k8 {    set my-column -11 }9 Q+ K3 O& `& g
    set my-phase -1% X! E1 R$ p  ^
    set pcolor brown + 3+ j- `' m6 r, c- I- a  q$ J
  ]
3 X7 Q) Y" b; }" Q  y/ M: s- D( k6 ]) L( p$ q: |
  ;; initialize the global variables that hold patch agentsets
! V7 s. C* \0 @( }  n1 ~/ K* Y  set roads patches with; T4 \6 w9 U2 K
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 G: u! v& T2 N/ F% H2 e3 @    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 s! {8 {8 Z8 k  e# W: t0 s7 I, f" o6 L) o
  set intersections roads with4 A1 J( Y2 m2 \' S+ a* X7 `/ u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
2 Z0 W- R4 l1 U- M4 I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* L- j# J9 f2 a& y' T# O0 [/ }5 }' ?( \( A1 p
  ask roads [ set pcolor white ]
5 d& i* }2 o0 f. [( ^, a" z    setup-intersections/ i9 f; j- ^" ^
end" E3 L& d0 @8 N
其中定义道路的句子,如下所示,是什么意思啊?+ I: E; ]7 n, E0 D
set roads patches with
6 r; M2 ]: Q7 F3 B$ t8 S. W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* e5 Y* @$ ?, O( P0 y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- `0 y' k2 H, L$ ]
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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