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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。
$ O3 g# ^- F9 y' _netlogo自带的social science--traffic grid这一例子当中,; q6 S5 G8 `7 z4 c# U/ s
globals
0 M# q& W& q9 F9 j& T[
9 y0 M/ S: W  _6 T' G  grid-x-inc               ;; the amount of patches in between two roads in the x direction
8 k, l% f6 V: G+ F" _4 Y  grid-y-inc               ;; the amount of patches in between two roads in the y direction$ I$ E( M) F. r! G
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if3 V( ^6 ?9 G* d$ e6 O
                           ;; it is to accelerate or decelerate+ _  ~# K3 X; q" P& L
  phase                    ;; keeps track of the phase1 s" F5 b  Y3 o; I6 O( u
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure4 F$ l8 D! Q& a& a4 M5 H8 d. y
  current-light            ;; the currently selected light
4 ~' J5 F. F% n" x1 H2 T& \) V# ^+ L2 \# q7 r) O
  ;; patch agentsets
& u2 c3 L% n( `$ D& n6 ?8 R, n  intersections ;; agentset containing the patches that are intersections
+ m4 {# O2 H1 @' p$ \$ N  roads         ;; agentset containing the patches that are roads
9 ]8 p# `' f" b  Y0 I; R! Q& y]
: j5 v2 R% ^- b' K0 z- |( h: q* ~! I- _2 H) o, Y& X7 X8 e% |
turtles-own" }% i( a6 G$ a  ~
[
5 C+ @7 F3 q5 X  speed     ;; the speed of the turtle
1 P0 @4 T% `( B3 B9 n! V  up-car?   ;; true if the turtle moves downwards and false if it moves to the right1 h: F8 f8 l8 g+ F5 ]
  wait-time ;; the amount of time since the last time a turtle has moved
, r: s: {0 w  @]
  X4 ^8 m, O! X* Y6 N3 i
2 ?- Z4 l# v4 Zpatches-own
! D7 ~  s2 O/ V% U2 s[& p9 h% u) w( n8 H# u
  intersection?   ;; true if the patch is at the intersection of two roads7 D% r7 h2 Z6 e% ]
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
! M; s3 N3 j4 t& V+ K                  ;; false for a non-intersection patches.1 w$ @# `; b+ S/ a
  my-row          ;; the row of the intersection counting from the upper left corner of the: t8 d9 v& R. v& L& ~+ o
                  ;; world.  -1 for non-intersection patches.
" u& K" M8 A9 a+ Q  my-column       ;; the column of the intersection counting from the upper left corner of the4 G# Y: p- m; f* z' h2 E7 h
                  ;; world.  -1 for non-intersection patches.% [+ A$ t6 R: E; m& [: A5 m
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
* `- r) R$ j1 j5 u4 A. z  A* w  auto?           ;; whether or not this intersection will switch automatically.9 P4 {! g! }6 D
                  ;; false for non-intersection patches.
3 ~& J- v3 Q- c]
- e+ [: Z1 r% B+ S  i& @* I! X( a; ~5 o" m  P
% g6 L3 B# P+ O
;;;;;;;;;;;;;;;;;;;;;;
- e: O7 O) z0 R4 o! R( {. F3 E;; Setup Procedures ;;
* y( O; o8 _6 D( Y- T7 I;;;;;;;;;;;;;;;;;;;;;;% q5 d1 j9 A) k: Q0 E- p
9 Z: ^  V9 C. d' i( P
;; Initialize the display by giving the global and patch variables initial values.$ _- q! A7 z! n. I% F) k- ~8 X1 e
;; Create num-cars of turtles if there are enough road patches for one turtle to
% I8 Q1 |. y: g7 q9 C7 W2 Y  ~1 x$ q( I;; be created per road patch. Set up the plots.
8 ?; B7 o/ O) p5 o2 f1 S' Hto setup1 D# e; X5 l# x# ?5 n" Y: c
  ca/ Y* B/ l3 o9 j- j1 |
  setup-globals
4 ^# N% X) E4 B* }- R* t& {, V. Q1 `, j
  ;; First we ask the patches to draw themselves and set up a few variables
. c% q7 J/ B; `1 R* x  setup-patches
5 }- z* }; S7 A* i8 t" f& U, s  make-current one-of intersections
* K: l: w( R" X4 U" V1 F. Z% z6 h  label-current; r7 U5 G$ s) ]

4 u. Q+ {4 O& j* w" Y  set-default-shape turtles "car"
" u* R% @: e. B  t# O/ c6 r6 d4 }0 r
  if (num-cars > count roads)
; k3 n3 R7 `2 _/ i  [- o( O4 a. v1 Q: B# g* V: m  p
    user-message (word "There are too many cars for the amount of "
0 C: W8 @  f% o6 G; |  J                       "road.  Either increase the amount of roads "# y  [$ Z- _: }; H
                       "by increasing the GRID-SIZE-X or "
0 v1 ]; b9 D3 f4 y3 @  T                       "GRID-SIZE-Y sliders, or decrease the "
4 Z) q1 ]  V' v: `% n                       "number of cars by lowering the NUMBER slider.\n"
0 z. v; _7 h" x5 L4 I( J" V6 C2 S                       "The setup has stopped.")5 R5 d5 X; N/ ~' U0 N6 l* q
    stop# Q9 V  x3 g4 m7 ?% H8 i9 v
  ]
% G" V' d% a8 e+ w& b3 ~' s- T" _9 Z& \" E. E
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color* j8 V, q: m" b, ^' |
  crt num-cars0 N* l) [+ O) o( g% V0 T9 U
  [
6 X" d# j5 B. S1 u3 I: i    setup-cars5 D4 s% y3 ~! n- C1 M! {
    set-car-color
2 \% @' J4 t9 C% U( w$ K% m4 X    record-data, ]5 U% p: B/ H6 \
  ]
/ e/ u7 D$ G  u# q  Q. D/ g- i& U9 V
  ;; give the turtles an initial speed/ `- _. q# y: e. ~+ o9 x
  ask turtles [ set-car-speed ]9 g2 T, }; W, _+ o% a2 L% F* _

, P: X; p% K$ U; c  reset-ticks
, M$ f3 j3 d3 R4 Hend" ]; F( Z. a, J* y6 B
, j, F1 h9 Q$ T4 I- `
;; Initialize the global variables to appropriate values/ v$ O4 x7 B0 W+ @& {' p
to setup-globals8 M4 |# Y: j0 t; [; c1 Q: @
  set current-light nobody ;; just for now, since there are no lights yet
4 k8 s1 v* e) n" G  set phase 0
0 e7 W3 |# q9 X  set num-cars-stopped 07 [2 _0 G% L( `* [7 ?4 l% c9 L/ V
  set grid-x-inc world-width / grid-size-x3 p! m7 \" H# K2 m
  set grid-y-inc world-height / grid-size-y
4 ?( y0 b% W' z. n! h& O" }# l; J# }
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
7 G, P' R6 G4 W+ b& K6 `# C  set acceleration 0.099
! u2 H( h5 B. J5 t; d' Nend% v2 ~: c0 P& a; H2 T
/ i+ s" `$ N) U! i! O8 t
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
/ T1 }  s9 [) l% ?8 D/ {, N;; and initialize the traffic lights to one setting
0 X9 z9 _6 l: d9 c3 a% Jto setup-patches. r, L/ h, W* W4 E& M9 C
  ;; initialize the patch-owned variables and color the patches to a base-color
- D, [$ R2 Z+ T: q& I  ask patches" q- W- [$ Y5 D
  [
( v; F% ?/ h+ |) L! s2 r    set intersection? false
5 p% D( I3 b3 {2 Q, B    set auto? false; ]. i& m7 j5 C5 }
    set green-light-up? true
2 B/ x- e& q1 R0 k4 R    set my-row -19 T3 _. L" Q4 H  y$ i; b
    set my-column -12 c1 h# G8 C. m3 r& [) N; o! m. P
    set my-phase -1( ~8 \5 D2 c$ U+ T4 T: Z4 @
    set pcolor brown + 3/ f) p  e, X6 f
  ]- t5 h! r& {. ]7 D- N1 v+ [
3 k$ I: y% a# C5 o
  ;; initialize the global variables that hold patch agentsets
- z* ]4 }8 p8 k  set roads patches with6 I0 t: W! G) i! Y# @  u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 C3 k. ^  v  @! v1 t' p& u& E" O    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* ^  V, z* ?( e3 S& n( i2 W  set intersections roads with
% I5 ?  K' {3 I. Q0 H4 N3 I    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
( d9 ^1 b( l) i- l    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ V* [" ^4 X  X3 W& W) L' H

5 N# S! q, y* e; H+ p! R  u  ask roads [ set pcolor white ]
1 M- w# K5 h! `/ z% P    setup-intersections$ O% K0 z, I1 ?6 ?1 T
end2 X* V2 ?5 L$ J: r
其中定义道路的句子,如下所示,是什么意思啊?
+ S' b7 B2 w. t6 ~6 y2 a set roads patches with$ p$ W" m) Z% e2 F, L
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! [1 z+ {4 g% B" s4 c    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ k4 W' N# ^6 L; w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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