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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。
- R) h2 {, O: N/ Ynetlogo自带的social science--traffic grid这一例子当中,% t3 L, z. Z- I" @/ q
globals
4 s2 I( t# S' P3 p$ l* J6 h[' v* W" E; s- \3 K2 q
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
" v2 g: Y) {$ }8 |  grid-y-inc               ;; the amount of patches in between two roads in the y direction+ Y- ~4 `+ S7 D- A8 ?
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if* u; t- V$ {- |1 e
                           ;; it is to accelerate or decelerate
; J2 |  x6 D% G  phase                    ;; keeps track of the phase' ?* o$ \0 ]1 h& \& ~
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure# S9 N  {4 D$ r) k, k9 o3 h0 M0 p
  current-light            ;; the currently selected light3 f3 J: g2 P1 L! I9 F
' l1 b* E1 ^- j4 \% R" d
  ;; patch agentsets3 I  x0 m5 U% e
  intersections ;; agentset containing the patches that are intersections
0 o+ N# u% O% ~5 P  roads         ;; agentset containing the patches that are roads
; i0 E, q$ l$ p: P]- m5 f# @( ]5 _# P9 Y/ c

# K& m7 F; ]" M, x* X! c7 yturtles-own
3 Z5 O  D) V( K: |* Z# @[
0 t7 x' P2 Q2 t7 A7 {! @2 \  speed     ;; the speed of the turtle# E7 B: B* p3 F2 D1 U- |4 w! ]) w
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right' y  A) L5 X. G) A3 \1 Y  l. ]4 n
  wait-time ;; the amount of time since the last time a turtle has moved
8 H0 Q8 q- C& I5 A]
1 a% V/ I- z. r& B5 _9 W
5 y# z4 q7 g% L. L( |9 mpatches-own' w* `( \6 y7 O$ S# t
[
! x) c9 r+ B9 i% B& A1 ~4 k% ?  intersection?   ;; true if the patch is at the intersection of two roads
3 K$ m9 x3 d% A, }1 \: ]& h  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
  Z" m2 M7 ]* C8 ]' o                  ;; false for a non-intersection patches.. s; g( M2 k2 a$ V% z& g; k
  my-row          ;; the row of the intersection counting from the upper left corner of the. e& E3 q2 x$ T  \$ X; K
                  ;; world.  -1 for non-intersection patches." @' w; g. C! J" p3 j
  my-column       ;; the column of the intersection counting from the upper left corner of the
& A( }0 r0 o& D1 A1 X1 ]                  ;; world.  -1 for non-intersection patches.
7 d/ i4 I- A" k0 z  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
  U7 R5 e3 W1 t7 p; h  auto?           ;; whether or not this intersection will switch automatically.$ d& ~( C7 T2 Y, t6 v! R
                  ;; false for non-intersection patches.
; x, M! J7 p% o$ A! b. G' e0 P]
+ T3 j0 g6 C5 D" {
) T1 Z1 a' q; n% d
  v0 j4 D. B: L& f0 H;;;;;;;;;;;;;;;;;;;;;;
$ Y6 Z  a5 j, @; h;; Setup Procedures ;;: @4 A( @' S5 V. o; a
;;;;;;;;;;;;;;;;;;;;;;4 H" _. d- G, G% o  Z, [

, ?8 S3 B: x4 T% @* o8 F( b;; Initialize the display by giving the global and patch variables initial values.* m( b7 h2 F) E1 U0 P
;; Create num-cars of turtles if there are enough road patches for one turtle to4 s- [8 x4 x8 i' ~" @: g: a
;; be created per road patch. Set up the plots.- f* [: Q* w' b: B/ W% q
to setup$ o7 _' V, F/ v7 |3 E4 h4 X) L
  ca# ]) @4 U  ?( u! h* R% q
  setup-globals
1 G2 b: L- J4 i  }' Z) Q0 s6 s7 \# E
  ;; First we ask the patches to draw themselves and set up a few variables
% Q7 U6 n7 p  n8 `  setup-patches/ Q3 J$ a1 p( [# \7 C
  make-current one-of intersections
( j3 @* l9 N& Z, H+ O' h  label-current
( w3 B9 b/ K* V8 o# O  y
+ l! ?/ a& o7 i3 Z) t$ B. p/ U9 L# h  set-default-shape turtles "car"" g# M0 ]# D$ H/ l6 g& C
9 A# B6 x/ _& p
  if (num-cars > count roads)
0 T, u6 c( w# m3 I& O' W1 F: {  [
* V- D  f9 q6 y( E8 T+ b3 l% q    user-message (word "There are too many cars for the amount of "5 I9 I7 l7 Q" @* W- H" O1 [
                       "road.  Either increase the amount of roads "
/ |# L; Q, ]( d                       "by increasing the GRID-SIZE-X or "" ?9 Q: y1 H4 G/ C8 w& R; [& H
                       "GRID-SIZE-Y sliders, or decrease the "
2 a6 d4 a* J, Q; Q: y/ e0 q                       "number of cars by lowering the NUMBER slider.\n"- z6 o) _0 C: c- u4 |
                       "The setup has stopped.")
, H; q" I7 q1 g$ W( {    stop
  U( h9 _7 x- [1 [8 V  ]) l2 E* T. y" d, R
9 T1 A; H3 g  p$ A' A
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
: t4 U6 ^% S3 Z2 D3 L! A  crt num-cars
  s% K) W! c* E, V6 k8 ^8 g  [4 j8 H: ]" W9 @1 R0 F4 c+ u
    setup-cars4 ^7 T2 U$ r$ t; C& W* T
    set-car-color
* A. S& @3 j4 H  a3 B6 r+ N    record-data' B, {5 h" G7 g% A7 i
  ]# z- V5 d& }. j2 @8 o
- Z% ]$ F/ {% _) n9 [
  ;; give the turtles an initial speed: t2 O- }- o/ ?# z! |
  ask turtles [ set-car-speed ]
9 X  L" L: c) W8 Y
  @9 d+ k( p% a/ b+ r  reset-ticks0 f6 I3 {/ W7 r8 R) [
end
: J, q3 r4 C. ]
: `5 [& }% {, g# z; O;; Initialize the global variables to appropriate values: |; D) k$ m/ a
to setup-globals; R7 W2 s  s4 M" [8 C1 e
  set current-light nobody ;; just for now, since there are no lights yet  O+ V1 _- O( |; e' ]& K2 t
  set phase 0  J; z0 V  N1 m
  set num-cars-stopped 0
1 `2 \2 Q1 m5 t" U3 L, {  set grid-x-inc world-width / grid-size-x8 [8 |/ D# x4 }
  set grid-y-inc world-height / grid-size-y* I2 Z! k' E4 c1 X

, ^% D* V$ v" q- J  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary+ \6 }: Z7 v7 W; t. `8 g4 L; R. C
  set acceleration 0.099
3 m. X* B* P. r/ nend
( k1 W6 C& u2 |3 e3 ^2 R3 i+ n6 G9 v; Q2 p& S2 W+ J" R
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
; B& C2 K7 G' C4 q$ V;; and initialize the traffic lights to one setting
6 a$ i" t! U$ }0 M6 Q; v, gto setup-patches
1 Q9 W$ E; j/ h  B8 P  ;; initialize the patch-owned variables and color the patches to a base-color& u$ H4 R2 T5 W0 g1 O! b$ y
  ask patches
2 G* s, Z+ m$ {! }( P  [
2 W4 u, A2 f* {8 p, C% S, z  a    set intersection? false" `  I  q) V. G3 }/ ?) y5 U& J
    set auto? false7 q+ F) }% U# C; |1 _
    set green-light-up? true
! h) X2 ?! G# Q' h6 G; ]    set my-row -1
4 k/ p! }7 y" V. S' J+ p    set my-column -1& i7 O4 {* a" L8 L
    set my-phase -1$ U, r" l' ~6 j) t
    set pcolor brown + 39 v$ K6 \; ^! {9 f; m% s
  ]
5 L2 j& e+ r# [  A+ H5 L) t# s
5 K7 M7 e! j" o4 i  ;; initialize the global variables that hold patch agentsets
/ w1 b3 N4 ]2 q0 i- L  set roads patches with
$ X- D6 b0 F9 i& H: j    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or. z, X5 H  q$ u2 e, [4 C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 ~! Q$ P( B  [) V' s) i
  set intersections roads with
4 K) R* n+ J& E& T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
0 B( ^# @7 W' t* `- j- a- g- Z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) L7 {( O; n) K" I5 e
# J2 X% V6 D8 c4 V% E' o# b7 I  ask roads [ set pcolor white ]6 N/ y! @; I% @  n% l
    setup-intersections
9 X) ?% S: r. uend
5 Y, p9 x, A! K- j8 Y. u1 j" P9 n其中定义道路的句子,如下所示,是什么意思啊?
6 q$ y7 I' X7 m/ t# m2 @; `" K set roads patches with
# X, `- }8 i" d. T/ b5 X, Y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) @8 M/ U+ c# `/ \% l    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 z0 f; R! z6 s/ n& h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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