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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。
; i5 W/ c, y* C: ]9 K' Unetlogo自带的social science--traffic grid这一例子当中,0 l! I, n$ g1 N( C
globals
/ H, P$ ~2 B5 o0 g! m8 w, W[) V) E& r2 O. ?7 o- |
  grid-x-inc               ;; the amount of patches in between two roads in the x direction9 c3 g! A: k" I$ Q4 b8 q4 \
  grid-y-inc               ;; the amount of patches in between two roads in the y direction5 s6 Q% s3 h/ a5 K. F
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
* a2 M; z# ?$ t- E" y5 k                           ;; it is to accelerate or decelerate; h! J  Z' G* {8 D3 w9 c- I$ t
  phase                    ;; keeps track of the phase1 i& C# a. J) s, E
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure& Z: m1 D$ ?3 `
  current-light            ;; the currently selected light
4 a: I  |! d# G2 F9 R
. r  Y  v, k  D& ]2 e  ;; patch agentsets3 C4 I2 W; H' u! M, L* s# Q8 N
  intersections ;; agentset containing the patches that are intersections
* G- o7 R7 z6 m6 x, M/ D5 X  roads         ;; agentset containing the patches that are roads
9 N6 z1 V  |( s( q+ n3 f; R0 H% a]
; l: f& @! j3 @
9 ^# m* ~' P. Y% }* Z/ Y% |turtles-own1 S* c, {2 v; l+ o
[0 l, p0 J1 a/ T9 f
  speed     ;; the speed of the turtle3 f: h9 Z9 x" |, ~: U: |
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right3 o  Y# |( U8 w. M
  wait-time ;; the amount of time since the last time a turtle has moved  ~' |& ~6 z4 S, w1 w; C9 Y+ q3 `
]9 u, N# [0 h% V# g& Z

; j( S2 [4 B# e' f. ~patches-own
+ h* K* }3 Z) E$ q5 F% F1 W$ ?6 }[
- K( \! a, r# b2 F  intersection?   ;; true if the patch is at the intersection of two roads
% S& h# u. k+ k% W  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
5 A4 Q& r2 g1 u  E. a. j                  ;; false for a non-intersection patches.
: }. A) c8 m5 Y* N+ t  my-row          ;; the row of the intersection counting from the upper left corner of the) I$ q0 e  H% B; P2 G6 \* R4 \
                  ;; world.  -1 for non-intersection patches.
% q& u7 i& G6 p0 K8 q4 L  my-column       ;; the column of the intersection counting from the upper left corner of the. v! K7 ~" ^% ]5 s: Y0 V  n
                  ;; world.  -1 for non-intersection patches.
4 e) u$ f' K4 _- X* l  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.) g7 _5 J3 T/ v! v
  auto?           ;; whether or not this intersection will switch automatically., z. P  i$ A& J# T5 {
                  ;; false for non-intersection patches.1 h0 V- I4 P( X: A, ?4 O/ Y7 U$ Q$ ~2 @
]
: U# }1 f. ~$ R, E: w% L- m& X! V6 z4 U/ ~

, B. `- i. i, }0 P( b2 B1 z1 ^;;;;;;;;;;;;;;;;;;;;;;: W. b5 R* o4 i8 S* d" }4 ]
;; Setup Procedures ;;3 i$ _& o  N( K7 q6 x
;;;;;;;;;;;;;;;;;;;;;;
- ?+ a0 K. l3 y  g* y
$ B/ W6 t& l* x4 g* g' l! a/ t: n;; Initialize the display by giving the global and patch variables initial values.' n1 c4 a" h8 A  ^& g
;; Create num-cars of turtles if there are enough road patches for one turtle to# T! q2 j5 w+ A% z+ L# s6 o
;; be created per road patch. Set up the plots.
& u, d- ^8 N0 Tto setup
2 {$ L5 |& _6 Y  ca, k- n* A% j9 h* e/ I
  setup-globals
9 ~1 o; {, P- c% O$ D. P+ H& \% I& V% e5 a8 K0 n' ~  z0 b
  ;; First we ask the patches to draw themselves and set up a few variables
" a8 |5 o3 k- L. ?) J% J  setup-patches# s, l: q9 p3 Q  r$ D4 [9 {
  make-current one-of intersections/ z8 }, S; S- B2 O; M/ V
  label-current
/ {& k6 s% H3 U: E  _, O4 m: w! Q  g0 D3 R9 F+ ~$ b. [% p: \
  set-default-shape turtles "car"! A8 l- @  f$ j8 L

1 q8 c& S1 p( V& b; K5 D4 L  if (num-cars > count roads)
8 C8 T7 D, U6 Y7 V* N( }# v  Z  [8 i9 G4 p+ b! w
    user-message (word "There are too many cars for the amount of "
3 Y2 H) n! {$ [. B4 p                       "road.  Either increase the amount of roads "( k. F+ b! X5 \( ]
                       "by increasing the GRID-SIZE-X or "
! {* H+ |. r# W# g                       "GRID-SIZE-Y sliders, or decrease the "7 t9 |% m& C2 `4 @
                       "number of cars by lowering the NUMBER slider.\n"
1 ?& p* u  O8 v( c                       "The setup has stopped.")% |  h; o/ ~- L4 k# P
    stop" }) S# G/ y( I
  ]" [4 x( H( a5 v3 c+ C) Y
. J& W" S# G) |9 O) B  W
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color% a6 \& [3 v) M( r- m
  crt num-cars
. u2 D; l% c# B# u  [
0 F: B+ {; }( n% p    setup-cars0 [& w7 L" @5 n8 x# F: }2 Q6 v$ K; {
    set-car-color* w/ m2 b8 c' Q! T
    record-data
' L% s" q. ?# D2 H' }: S$ f  ]
/ R* s1 Q/ y3 n, k1 N, d
; P3 O; ^  f) j$ c% ?3 c6 V% C' w  ;; give the turtles an initial speed
8 v( W/ {$ P# l- Q& F! p  ask turtles [ set-car-speed ]; y9 R# N* X% ^7 z1 R

  q" W. _, Y% ]; J( r+ W  m  reset-ticks
& ?% d8 w( _) L1 f6 |! `- Fend; D0 B- V0 ^+ E& U
/ i9 j' J4 M0 |
;; Initialize the global variables to appropriate values& E. k; e4 t$ e' z+ Q5 [) j
to setup-globals
+ Y% L1 h+ S% \  Z# ^  set current-light nobody ;; just for now, since there are no lights yet
8 M* [( B) f& M- L  set phase 0
6 z3 y0 }, ~* H  set num-cars-stopped 0; d9 Q' V; n! C7 R) O) I* x
  set grid-x-inc world-width / grid-size-x' s9 \) t! U6 `
  set grid-y-inc world-height / grid-size-y% @. E6 d8 U9 C) _2 C* W
9 l6 \2 o$ d; c+ y5 {6 e( \
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
& S8 o$ N& H" G& N( V4 Q5 t9 f( F  set acceleration 0.099
' \# `- K" I: B+ Hend
, ]3 w; Z7 v. f: ^* W! ~% b+ M0 q8 P! f4 {) v8 C
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
  c! P" y, m2 z6 g4 m' b! L+ x;; and initialize the traffic lights to one setting# ?/ ~! F# T1 h6 a- [' R4 m  D
to setup-patches
& W4 X; b+ b- n. T: X6 m# _  ;; initialize the patch-owned variables and color the patches to a base-color' }$ T! `# e. a( H2 v+ i
  ask patches# h0 }, A6 J6 O/ u* j0 y4 X
  [
% o2 A) N" n. a& A/ d    set intersection? false
7 _. ^! [2 m7 C" v$ z' c% g    set auto? false
! Z9 \8 m3 k+ ~) o    set green-light-up? true
3 T2 l+ A0 N" o* B$ o6 Y7 b9 E    set my-row -1
( p3 m6 N" s6 {9 y# @, A4 y* K. p: J    set my-column -1" \6 t4 K) z& `+ [0 W9 E9 Z$ g# \
    set my-phase -1
: A; r2 _7 `4 c, H0 ?  N6 I6 [    set pcolor brown + 3
; J0 G/ o+ @0 {+ l# t  ]" c& I- J% O+ y: j* H! y! d4 w

) T# ~" E, _0 P6 Y5 h5 u  u0 B  ;; initialize the global variables that hold patch agentsets; b/ `& b. ?* n& r* s
  set roads patches with8 j! k- r! x# h# A+ `/ }
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or0 Y& E) s, u- F$ F6 @- ~0 q! O
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 L! c% `  z4 T7 `. z8 L  set intersections roads with
' r9 k5 v/ t. i; b) j0 l    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and) p$ [. X) D- k/ d: ^
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 U  n. w$ z' C& T5 Z1 C
; b) L. N2 J* ~! Z5 i7 W, P3 {* ^
  ask roads [ set pcolor white ]9 d. N  L+ o4 S* x1 c, {; `, \
    setup-intersections
# Y# t1 S( ^, D& mend
8 I) ^) D% I4 l其中定义道路的句子,如下所示,是什么意思啊?
$ U, s4 o2 {2 G9 ~  I5 U/ u2 s set roads patches with% b  L4 O3 V$ ^3 X  J) l5 S( k
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 Y& a- a( N: c* T  @+ s    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: C! a, H, L5 b2 ]3 \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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