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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。
. U5 v4 y, J+ z$ s6 Ynetlogo自带的social science--traffic grid这一例子当中,1 {0 A  @4 \) E, \
globals
( m: U$ ]7 b0 K# f4 f( n/ V[
( I$ E- x; y- s' n+ V9 c  grid-x-inc               ;; the amount of patches in between two roads in the x direction* a% w6 q. d3 f5 n& W# M. T
  grid-y-inc               ;; the amount of patches in between two roads in the y direction7 C4 ~& I/ f3 a" G: I2 `
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
5 w; {$ b( k, }  @2 k2 e& H/ x                           ;; it is to accelerate or decelerate
, \* ^" ^% l( l2 I' l! o, {8 O  phase                    ;; keeps track of the phase
, T5 d& M& i! u- N, f  a9 B  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
" W$ E4 b, S% f% o  current-light            ;; the currently selected light2 u" m& U; u8 u% \8 `" u( q) ~2 K
3 e/ N2 B9 L/ x2 v" z  q2 }
  ;; patch agentsets
% f4 J2 W$ T( |' }7 a# k: J: R  intersections ;; agentset containing the patches that are intersections
% {2 b. y/ B3 b; a) ?  roads         ;; agentset containing the patches that are roads, y2 x- j1 U) Y2 F) f' @
]. D* T: v3 w; H0 h( ~

9 b; y2 b( Q, m5 k5 Jturtles-own
- a6 _* {5 U, b( C' c* R% {& Q[7 {. G* b: A0 s1 e, y" u7 R
  speed     ;; the speed of the turtle
& K/ X' N/ Y6 @. k; n: B9 i( A+ }  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
0 Z. ]2 I2 Z$ g: U2 L9 B  wait-time ;; the amount of time since the last time a turtle has moved
7 U) e- H" d; }" u- C& t. k. g]
% T/ k4 w- I: b; n5 H) Y" l. }/ S/ V. n! K$ Y* ]* _- e0 C
patches-own
& f# m% h1 ^) K# T, x1 i1 t[+ B1 R6 m& S: v$ h4 j
  intersection?   ;; true if the patch is at the intersection of two roads
* P, C, U, Q7 e# X7 P5 N  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
$ Z$ i  S$ R2 o) C                  ;; false for a non-intersection patches." d9 e; r, S% B' Z* V, D( s4 e
  my-row          ;; the row of the intersection counting from the upper left corner of the
7 \) k" c, o9 l4 ~( z                  ;; world.  -1 for non-intersection patches.: p) V' P& x* k
  my-column       ;; the column of the intersection counting from the upper left corner of the
# F! S9 E. q4 q2 x- d, K                  ;; world.  -1 for non-intersection patches.
2 h* P" o/ M. J2 g5 D) J  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.6 e& T* e# B! n# A# M0 E% \
  auto?           ;; whether or not this intersection will switch automatically.9 K' K: g/ c# o! |; I# Z3 _& {
                  ;; false for non-intersection patches.) R# l7 y% b; h* N/ d9 A4 |' ^
]
& u3 i! z4 T" v4 L7 }7 e
- S2 w3 l' q+ }1 L% h/ Y2 s
& l' ]+ c5 _( U1 J7 z;;;;;;;;;;;;;;;;;;;;;;8 u% X3 I7 C) O9 {9 _* |0 U
;; Setup Procedures ;;
/ d0 e1 \8 {+ R;;;;;;;;;;;;;;;;;;;;;;
  m, ]0 H0 E# {& h5 c- B, V0 F/ ]/ h- T, G0 ]
;; Initialize the display by giving the global and patch variables initial values.$ g' b! M' g7 o$ X2 _$ ~- J
;; Create num-cars of turtles if there are enough road patches for one turtle to0 f& T% L2 o3 g) ?* d
;; be created per road patch. Set up the plots.+ f+ a/ W& J" Y+ L* c
to setup
% r# ]! v0 _/ t+ Z% A  ca3 @3 R7 t' }  J- U
  setup-globals
# l$ N" B! X4 ^+ U) _  d6 F+ H( `8 M% l- `$ [# B- s
  ;; First we ask the patches to draw themselves and set up a few variables
, L- \, X7 {( y( U  setup-patches& |" Z7 C. l% V
  make-current one-of intersections
  }. Q0 q) U/ i, \7 l$ E; `0 r  label-current
$ [1 D( T) c) I1 u7 B: X
: P, B) l" a! l) p2 h' T$ A  set-default-shape turtles "car"
5 ?- J. D" B1 o7 \) w# ]8 r7 ~- |! Y1 ]
  if (num-cars > count roads)
; B- b, k2 v8 N) R  [% \; c6 h# I$ U5 C
    user-message (word "There are too many cars for the amount of "0 P  T2 W, Y+ ?# _8 M! Z* E
                       "road.  Either increase the amount of roads "/ `$ k- |  i2 ^( ~9 [: j9 D, t
                       "by increasing the GRID-SIZE-X or "
" G' @5 F7 \! \8 q; T                       "GRID-SIZE-Y sliders, or decrease the "0 H; Z' a7 S: R, o
                       "number of cars by lowering the NUMBER slider.\n"
+ ?5 g! g- Y0 _0 h                       "The setup has stopped.")  {! H5 y; R. v* B
    stop" J# Q  x3 Y- a* H( T5 m. K/ g) I
  ]7 W! u- e' M( @7 n
9 C; j& |; }0 n0 ]
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
( d. o- \" c' E* |0 }  crt num-cars
9 X9 r$ f. P( l( x/ T, @" ~" s  [$ Z2 m. T+ }+ n. c3 n2 M% \
    setup-cars
7 k2 g- x3 E+ j0 @: b    set-car-color
1 u! D! b# y' a3 z3 L1 R/ ?4 B7 r    record-data
2 h6 b4 u" \" b2 S5 N! B  ]
: o% w. W; P4 ~! d) [3 O1 A$ V
. J4 P2 z; e) E8 i. j) x  ;; give the turtles an initial speed2 t* H% |. I/ m* ~3 c, v5 ?
  ask turtles [ set-car-speed ]$ E6 r$ R1 P& V% x+ _+ ?" i
, |$ w  J8 H0 D+ N' @
  reset-ticks
% m1 h# s* H- x* cend
" p; z7 Y, D8 W* ^" }9 _$ t$ l! {0 x% B+ |1 |
;; Initialize the global variables to appropriate values. q; `+ A; v! O7 K7 p" x  P
to setup-globals
2 ]" [9 M8 R2 n$ Y+ f" c  set current-light nobody ;; just for now, since there are no lights yet( Z3 S) X0 S6 l7 p* i- j
  set phase 0
4 A$ H- i" I: q& s( h  set num-cars-stopped 0
. G: B$ _" P3 k8 l9 n: [9 L  set grid-x-inc world-width / grid-size-x
* C& f1 b% f& n% [7 i- B) E  set grid-y-inc world-height / grid-size-y
  E* _+ }: `, T
) l- @4 d$ x. M) s; U  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary8 I" j+ c: _0 f8 l0 e. A6 \
  set acceleration 0.099
7 k' e# @: z$ q- W* Hend
: S5 o  H6 C$ F, V. \- M8 B8 I( o2 I& c( d) R) p9 ?+ d$ N
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,: f& [; ^% f- O: `" J; y, m
;; and initialize the traffic lights to one setting7 P9 g3 k  \: {
to setup-patches* D7 C7 x) d; r! Y7 K7 s8 D# ]; U
  ;; initialize the patch-owned variables and color the patches to a base-color+ s- U7 a- [  y; t* e4 K
  ask patches$ e: i' e2 K4 ?  x2 @
  [
% L2 w  J1 y* F3 W* S! O, Y    set intersection? false
) B# \* N( N6 [2 M4 S4 s! i5 F    set auto? false- t" A: f  V& \: i% D4 C- n
    set green-light-up? true
* m& {! ]) p, j4 A    set my-row -1, M$ m. ~. ?8 u; O/ o
    set my-column -12 p9 o. y7 b6 q! z2 o4 e4 i
    set my-phase -1
& `- b- S& N9 b/ L8 C    set pcolor brown + 3( \2 V# n3 u0 a! U7 ~0 ]3 t
  ]
" f5 Y" I, \6 B. T1 ^- U
/ e( X" c' S2 e" j% p/ |  @  ;; initialize the global variables that hold patch agentsets, o, @- p. q3 k) n! J
  set roads patches with! s5 x; i% r5 c, \* a  |
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 [# ?- }) M: W( c4 l8 j: z4 }    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  P5 x# T1 q. Y* u: d/ }  set intersections roads with
( W# M6 H* W9 H) |" S9 e& f    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and9 i! e7 n% Y. a! X5 |5 s
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" V, v9 p1 g+ K+ Q% X& d  E
6 {, X  w) p+ u' A! S$ r- B  ask roads [ set pcolor white ]
' {* ?( H$ u: V7 `- X    setup-intersections
6 R+ ?& x; I4 {$ cend* o+ o, H4 ^- H0 b6 |
其中定义道路的句子,如下所示,是什么意思啊?
3 p' t" P% i4 _0 t$ m set roads patches with2 s% h8 ~# l1 I  P8 o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 ~- S2 P. [! B    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 Y9 t! s( v* S4 [8 ^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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