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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。
- h" n) r) A8 g- }! enetlogo自带的social science--traffic grid这一例子当中,
  {7 W- K6 Q. F' C& g/ X" ~( Kglobals
3 i. ]) A. l% P" c8 V! `[
1 y" f9 Q. s) m6 o* q2 E; F  grid-x-inc               ;; the amount of patches in between two roads in the x direction' }8 Y2 w/ j+ Q- c5 L6 J" ]
  grid-y-inc               ;; the amount of patches in between two roads in the y direction& {8 O2 I/ u2 F  G# J9 n
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if8 d0 w- T1 {% y& n+ O5 }
                           ;; it is to accelerate or decelerate
9 a; X4 g' H6 F* W# s* `  phase                    ;; keeps track of the phase
; L" Y  e, ]# _/ n  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
- q/ R4 \2 i) _6 h* V; e5 G  current-light            ;; the currently selected light
$ I. S3 g6 `+ e8 E) r, u- D8 o, D  ~0 U1 E5 D8 Z7 H
  ;; patch agentsets
. @) i/ ^7 c) d0 q, |9 ]  intersections ;; agentset containing the patches that are intersections4 V9 d# |$ E/ K# A- |
  roads         ;; agentset containing the patches that are roads
* R0 o4 ]; J- T1 T, w7 `, O# ~: []
7 b$ }+ M# V, a3 u+ J. C0 y6 s3 a/ q# L7 p6 c, N
turtles-own  \0 {0 B( O- s' R( H
[
) L) x9 H: H9 u: C8 z, N+ _  speed     ;; the speed of the turtle! q' @" @, `* R/ i) v* g! X
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right" A. I, G5 v: e$ K: U* T
  wait-time ;; the amount of time since the last time a turtle has moved
7 L( s$ }! `5 q1 [! A, K]
/ O" r. Y( Z- r5 D/ ?) _' k9 W8 n! i0 `7 O  a0 i3 d
patches-own8 k7 `2 o- @) b# }6 b
[
0 m% S1 o; y( P& G3 q. u$ o7 `. w  intersection?   ;; true if the patch is at the intersection of two roads4 K7 j8 w$ M$ @. \
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
6 U1 D9 U7 D  t1 `                  ;; false for a non-intersection patches.
+ K3 N/ p1 {) f, m$ j: T  my-row          ;; the row of the intersection counting from the upper left corner of the
8 e% E( K2 p3 Y1 H                  ;; world.  -1 for non-intersection patches.2 Z# A; {- Z2 x7 a
  my-column       ;; the column of the intersection counting from the upper left corner of the
6 f( t6 P. `" e( ^6 B- @# u                  ;; world.  -1 for non-intersection patches.; j; t3 Q! [7 i& h9 @
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
# n, M0 m+ I& o- K$ N, o  auto?           ;; whether or not this intersection will switch automatically.8 b2 p# y  X3 U+ I2 Q$ T
                  ;; false for non-intersection patches.
# n( z. l8 I1 u0 A5 V4 w]1 @& w5 E1 n/ `/ q& H

7 B( Z6 E1 Q0 c0 |7 u2 R$ b- \8 j! m8 ^, G7 U
;;;;;;;;;;;;;;;;;;;;;;) r6 r( B3 |4 S4 X" h0 Z
;; Setup Procedures ;;
1 N; P: |8 p8 B& A# l0 ^;;;;;;;;;;;;;;;;;;;;;;) A0 `5 E/ N$ h

- q* q6 |9 }- {" @;; Initialize the display by giving the global and patch variables initial values.
1 K3 J$ r+ v# ^) s4 a3 ~7 J;; Create num-cars of turtles if there are enough road patches for one turtle to& q( `" [' |& u) g9 g
;; be created per road patch. Set up the plots.
7 S4 j2 D' F3 H( ^  Zto setup& c! K2 v( ]5 ?$ P3 u5 `$ u& }
  ca8 Q% O+ X1 N* C4 {; v
  setup-globals
) y7 K) x0 J5 B( ?, G% G4 k! [% w6 k" `5 k: I) r
  ;; First we ask the patches to draw themselves and set up a few variables) E* {7 ~6 F: N/ D
  setup-patches
3 j. W7 q9 Y/ n# Z  make-current one-of intersections/ ]. B! v/ L9 P/ Q
  label-current
1 g: T# h" T7 ?
' e8 t  G! `/ I; M/ w3 A  set-default-shape turtles "car"
0 j" u  g" S/ N' }8 [* G
3 J& k) P' L- b. n  if (num-cars > count roads); H& y. t5 e/ K0 \6 D6 g
  [; h0 S$ a5 M; N9 z. y+ e- `
    user-message (word "There are too many cars for the amount of "  Z. U% f7 k* H8 L
                       "road.  Either increase the amount of roads "' z  v/ g" \1 L* p% c* K
                       "by increasing the GRID-SIZE-X or "
' L' n: C+ r7 l3 C" B' U$ ?6 W                       "GRID-SIZE-Y sliders, or decrease the "' g% c, Z& [. ?6 r$ g5 r
                       "number of cars by lowering the NUMBER slider.\n"  K& H2 `8 D( |- a
                       "The setup has stopped.")
, g" {$ `( z: x' v+ l- B    stop1 y; p0 i# n2 K7 k9 T
  ]
4 b' }6 }% n1 ^/ M* y0 v7 ~
) P3 Z8 j9 ^2 w: v+ q$ Q8 _* |  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
1 \! j: {$ N4 X. c4 L6 A2 C  crt num-cars
2 U0 n" m8 q- g1 ~; M2 i  [) k; g$ ?; c; h1 L$ J9 ~
    setup-cars2 u) a- d4 {# w, U
    set-car-color  {! y1 u9 b' f
    record-data0 R8 w2 r4 y0 ~: E* E- A) a
  ]
- g4 l" a9 `# I7 X. L% K* _
' N1 \5 E  a; J8 Z. b2 ?) `1 y  ;; give the turtles an initial speed8 L) W" E# O# Z( \- C: Z( ^
  ask turtles [ set-car-speed ]) _) G7 q5 O1 R" J6 j; V2 R9 [

1 O, D# d& ~6 C4 ^, L" r  reset-ticks3 Z# ~, r/ I' Y, W6 n7 c, M( C7 i  m
end- c7 P' Z/ _) x7 O: P' ~% N

6 A. _, q9 O" s" Y, r;; Initialize the global variables to appropriate values
6 o6 u, F4 f5 _to setup-globals
5 r  u) w  @% V( i/ {. l  set current-light nobody ;; just for now, since there are no lights yet: U+ d6 h+ g( i* I" r
  set phase 0
0 y0 Z3 D6 N+ t! @! H$ G  set num-cars-stopped 0
* b0 m- D' b2 n! d0 x. h! s; w  set grid-x-inc world-width / grid-size-x# |0 x; q2 h  G7 F2 G
  set grid-y-inc world-height / grid-size-y0 X. j) B- E; N6 H) e; K
5 d4 `( J2 Q( ?; O8 j+ i* `. S8 h
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
' _! ~- ?+ D+ u) U( a5 G3 x% ?6 I# J  set acceleration 0.099' d0 E/ {" p- i5 a2 M* U% u
end) u# W* B5 P8 |
; k9 u# x4 P+ `6 d+ g" ?9 [: \
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,* x& y2 X4 m2 A' r
;; and initialize the traffic lights to one setting
: O0 _2 N& g- z0 Nto setup-patches
2 N" I- e: k1 H8 }2 d  e  ;; initialize the patch-owned variables and color the patches to a base-color
2 k# y0 x1 N! g& W  ask patches/ U' d, v/ u) B$ ~& m) G( L
  [
( h0 T/ t" A! I: S    set intersection? false
1 T$ G& n6 J7 t/ Z/ `/ p7 X    set auto? false2 V0 W- j5 K5 M- t! Q. ?
    set green-light-up? true
# Q/ c* k1 G7 H! [1 X# X. B6 d    set my-row -1
! v) C# Z7 F2 @, h6 s0 R. h; Q    set my-column -1
5 \0 E8 R/ B) M) r3 R6 `    set my-phase -1
$ h' `8 ^) M$ Q' p    set pcolor brown + 3: v3 ]' d7 H0 `8 O; S  e3 n- [
  ]9 T; r! p# s9 _4 _$ s5 v
( u+ p/ H* J/ u% e! e
  ;; initialize the global variables that hold patch agentsets
$ H- Z2 A8 R  R+ M: I/ \  set roads patches with0 Q; d, G$ y' |, U) p' N) Q/ H, o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) g/ I8 W% _, k: Q0 K, s6 n: t    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: V5 J: a7 O8 N" I, [; b  set intersections roads with
: S6 V# b- S6 j) [' E    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
: [5 U- v9 U# f2 v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& E( L+ p. X1 N) }( c3 u

3 l6 y0 H  V0 E% z. C5 I% x  ask roads [ set pcolor white ]
* E/ l2 Z1 o& r    setup-intersections. Y) o  E0 z! G6 B! Y$ n0 Y
end- V6 ^  C- N. A& ~6 N6 n
其中定义道路的句子,如下所示,是什么意思啊?% w; ]. m4 m( |1 N1 ?2 [0 W3 R
set roads patches with
" ~! J( q/ \# {" I7 y8 w( G    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- d+ I( }6 ?# C1 E8 s$ [& g
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" }& p; Q+ s1 r4 t; J
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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