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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。& M# Y/ \5 n9 l  h# B
netlogo自带的social science--traffic grid这一例子当中,
2 n/ m2 Z/ \4 J5 v) Iglobals
# k. w7 B: e  {* o" r[
$ E# |: X, L3 }" C5 V  grid-x-inc               ;; the amount of patches in between two roads in the x direction
. U$ y% I- P6 R: Z$ H  T8 p  grid-y-inc               ;; the amount of patches in between two roads in the y direction" \: r. m: i3 @6 e( |3 }
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if& m& K, a3 o( I- G3 V
                           ;; it is to accelerate or decelerate
( {& @% g7 |( q7 r( [1 D  phase                    ;; keeps track of the phase
, M/ `: X; c. c7 Y: D  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
0 ~) N1 p# {8 m+ I3 ^6 N+ [  current-light            ;; the currently selected light
- u- w8 a9 C9 Y! A- n" E( j( I4 v# Y3 f
  ;; patch agentsets5 A( @9 o; a  e/ ~' r
  intersections ;; agentset containing the patches that are intersections7 G% v. Q( {3 E6 }* M$ n- R
  roads         ;; agentset containing the patches that are roads
3 `8 S- N' d. M. A0 Y], V) w8 I  e# O- m0 q/ V/ G& P

0 p4 a6 m4 F9 Q! d+ i1 V: e$ ^( [! wturtles-own
" @/ W) E: ^# M3 V* c( ^+ {[: d# W- U) ^. x: R6 `9 N* P
  speed     ;; the speed of the turtle* Q5 w5 t2 j" D$ Y1 N
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right+ J) Q" X% h: Y" J* j# C
  wait-time ;; the amount of time since the last time a turtle has moved) V2 {6 I7 b  e4 }# B, H
]
! g$ ^9 r4 i9 ~0 S" D. `) [. U; \) Q, [) J
patches-own9 V8 |# v. R" i+ i* N' K& g
[
& T6 \. y1 N8 o3 Z  intersection?   ;; true if the patch is at the intersection of two roads
& }& w2 H: k2 f  l- w  g  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% Q- ?2 b7 ~' O9 k3 n, G( X* T# ?                  ;; false for a non-intersection patches., ~& D4 Y+ Z, a
  my-row          ;; the row of the intersection counting from the upper left corner of the4 N" o2 r0 ^0 w$ N  \
                  ;; world.  -1 for non-intersection patches.* {% y3 @: g, L: X& P
  my-column       ;; the column of the intersection counting from the upper left corner of the  U4 J! r( o# ?* H# V
                  ;; world.  -1 for non-intersection patches.+ R9 @1 B8 r% P/ d: M) k* }
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
8 ?* _. w  z& r  [1 F- F  auto?           ;; whether or not this intersection will switch automatically.) _/ n1 Y+ Q0 I$ x, C9 ^
                  ;; false for non-intersection patches.
# f4 ^; g" B3 q$ q]7 h, q4 O* H% {" k# ~0 y2 p0 H
8 a9 u; d% n  ]/ |- i( a; b; l5 T& K

: f0 {4 W/ x' y2 G1 ];;;;;;;;;;;;;;;;;;;;;;4 t3 [3 X1 e' J8 t: y3 Z
;; Setup Procedures ;;
% h+ h2 z: h3 f: E. y4 H, e. K;;;;;;;;;;;;;;;;;;;;;;0 D/ [; p5 H5 t' D

4 H- n5 m2 C& U- E$ S( ]3 H;; Initialize the display by giving the global and patch variables initial values.
6 i1 d' w4 u( H* Y. c;; Create num-cars of turtles if there are enough road patches for one turtle to% k8 d  l9 K; _2 e( K& g; A& N
;; be created per road patch. Set up the plots.6 S! T6 r3 n- @/ H
to setup
  R+ o6 W/ V7 l; r( s. _  ca
4 }7 G1 L* R& T( s- Y6 J  v  setup-globals
# _) F3 G( W+ e: H5 B3 _
! Q4 c( B. `' V  j2 I  ;; First we ask the patches to draw themselves and set up a few variables4 @/ I4 ?' i) M" w. ?
  setup-patches1 f: C- v+ y8 x- b
  make-current one-of intersections
9 m' `& J- B+ w6 [) e  label-current
# K4 \/ m2 B  W  V
) w! C* g) ?7 D  set-default-shape turtles "car"  h$ Y9 F) ?# i" z1 ]% u$ M1 t

$ g. D: e' |3 |( X2 V0 e  if (num-cars > count roads). K  O/ C* ?& A  S) R5 F9 s
  [
* H8 P2 k, ?# q  ~    user-message (word "There are too many cars for the amount of "
3 I! N$ a8 R6 p! F  \" V* H+ U8 ?! C                       "road.  Either increase the amount of roads "0 U% n. P! W# `+ c* l% L
                       "by increasing the GRID-SIZE-X or "
8 @7 i& |9 r( M7 U  X                       "GRID-SIZE-Y sliders, or decrease the "
9 }, Q+ b8 L; D, K! G                       "number of cars by lowering the NUMBER slider.\n"
* u; Q! j+ X: i; w5 B, `                       "The setup has stopped.")
! }* W( ]9 d8 D4 \    stop* a" H. W3 e1 t7 m$ h
  ]9 M: G  J1 Q: x$ ?1 L! a4 z
3 Y' W$ x- }6 T2 ^" n" v9 z8 s
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
) ~6 T0 I" K" a& K  crt num-cars
) P4 S( N7 I# x5 u  [2 ^- m5 D( z# a/ `' J% J
    setup-cars3 S8 `3 Y: D3 {1 V! }
    set-car-color* p& p5 G# N, i. N% x
    record-data# o4 \! ]) m1 U1 Y. d% d
  ]6 S  r: N; D- B- k+ [$ r. A; }
, N% Y, k! S% r% g9 j, ~2 q, ?
  ;; give the turtles an initial speed, a. F* g( h2 o0 o/ A7 G
  ask turtles [ set-car-speed ]
$ E- q1 d5 j9 M5 p* W# Z! g
* S. I& C1 P  Q. V" m  reset-ticks
: c& C2 K% ^  `( u0 s9 `end
, [: E' z4 |! A/ H8 e3 G( I; k) Q- p# H1 a
;; Initialize the global variables to appropriate values; _8 c( D$ V9 o4 B5 ]
to setup-globals
8 S% y  {2 H$ o3 ]' c' E" |) ]  set current-light nobody ;; just for now, since there are no lights yet
9 p- r; |7 _; `* q$ r  set phase 0) K: x4 u# X7 [6 Y; r/ f  N% `
  set num-cars-stopped 0
: K. ]7 J; k: g% H  set grid-x-inc world-width / grid-size-x
$ }8 ^8 e8 r, @0 k* e/ h6 T' d  set grid-y-inc world-height / grid-size-y1 |3 r+ }9 J1 o
. U; [% N) R* C  O  N
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary4 q" p: K6 T+ N/ V' n( v; T7 @1 v$ g/ U
  set acceleration 0.099
$ l# i- k# p- ?( f; Qend
, Q2 c  F9 p# }0 V* V3 i1 p( _, g
" j# }2 C* F# u& s# Z  q;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
4 H) u! H7 z# o;; and initialize the traffic lights to one setting
2 y3 y0 z; ~2 V: Hto setup-patches
% K' s# [, ]! x) O  ;; initialize the patch-owned variables and color the patches to a base-color, q7 F1 E4 B. H
  ask patches% {7 ~  l! x5 j" ]
  [
! C) `6 o. X+ `) B# e% b2 r' ]    set intersection? false
3 l$ [  k1 E: B8 R+ J# |) g    set auto? false' m% {' t9 E6 t) |3 f
    set green-light-up? true0 E; f1 l+ Z3 V9 L
    set my-row -14 G# m5 q: P/ \# r1 ?& m
    set my-column -1# P( `) @3 ^. u$ @' @
    set my-phase -1
  z/ \- E7 [$ p5 _, s6 C0 |$ `    set pcolor brown + 3
2 y; D% G' M/ g( \5 |  ]
" x  q* U1 S. @! R: o
. b* i1 Z4 M6 n/ ]: J  ;; initialize the global variables that hold patch agentsets: N( F7 i) K+ r5 L! G
  set roads patches with, D' E4 F+ g6 w  Y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
; H3 h% P" N! a) b6 {    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) w1 J- s7 O1 q/ N8 X6 e. ?  set intersections roads with
9 h9 a  V6 ~. \! T, B; l    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and& n0 N& V3 j# n, P
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 f5 t4 G$ W* P3 @, K* a2 D) N/ G2 S
  ask roads [ set pcolor white ]: z% S+ B) G, h+ g( y7 W
    setup-intersections6 `- i+ `" Y) r& c( S% s- Z9 A1 ]
end1 n5 N: x* p6 ]; |! k8 v
其中定义道路的句子,如下所示,是什么意思啊?5 A, ?, K, J( C* E
set roads patches with* f+ t5 u: k( A; Z' {) t8 {, j
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: t3 d7 @9 [8 ^, T9 x1 ^
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 L2 M0 x8 Q& o! p
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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