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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。
: L) B! h4 ~4 g3 |% d7 Q, o4 Gnetlogo自带的social science--traffic grid这一例子当中,* {3 ^. D5 Y4 ]9 s3 o
globals
2 ?% n  j% p% _3 T4 H# g[
/ g/ S; a! x! Y9 f: X: A+ |* p  grid-x-inc               ;; the amount of patches in between two roads in the x direction
5 ~9 Q) Y) l+ k4 K, e3 S' S  grid-y-inc               ;; the amount of patches in between two roads in the y direction
* _  @8 F# g: d0 @& |: M: V  acceleration             ;; the constant that controls how much a car speeds up or slows down by if# N. s6 S, R6 }# P7 f
                           ;; it is to accelerate or decelerate
% q: b  c6 e  G3 W: Z8 N  phase                    ;; keeps track of the phase3 ]' t7 t7 ]* |+ G) Q* Y
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure$ J. r2 R5 W: l0 B- q
  current-light            ;; the currently selected light
* h% N6 s& l4 `$ G8 b2 n. ], |$ r$ X5 |* l# E; h
  ;; patch agentsets& b% @( ?; ]- j. m- V
  intersections ;; agentset containing the patches that are intersections
7 z- h& t& R% x' W9 W2 _  roads         ;; agentset containing the patches that are roads
* z$ \1 @3 S* B4 s- ?' l]
2 }' F# {! H( `% D
6 j" W, e$ o0 U8 P: x* Rturtles-own
; V+ n) g" Y, w% s+ v( m[
4 Q' c, B- N. F6 P$ k8 N% ?  speed     ;; the speed of the turtle( t2 d/ j/ v) P
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right& f! B7 H, M$ x# M
  wait-time ;; the amount of time since the last time a turtle has moved
( Q; H6 T; {# g8 Q% i! X0 X]3 B: G: D/ c- ^' A4 b2 r* t

3 j  T& {5 Q2 K% Q, Dpatches-own
- a* j! `1 Q0 G* c[) k0 j0 H' g. Q! }
  intersection?   ;; true if the patch is at the intersection of two roads
' e3 D( z1 J4 a; g# E  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.4 t( w$ U7 D' @* e9 R
                  ;; false for a non-intersection patches.
+ B& }3 s+ X+ d0 ~( ^' z  my-row          ;; the row of the intersection counting from the upper left corner of the& O% T0 O( j4 O% g8 C& L$ p
                  ;; world.  -1 for non-intersection patches.2 }: r; \# t2 w; y$ w" |" |! u
  my-column       ;; the column of the intersection counting from the upper left corner of the
4 H% ]+ _# c& e$ n8 g2 {                  ;; world.  -1 for non-intersection patches.. S) X1 a. c' K8 D& C3 V% f/ {4 {
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.* d" ]) f$ r1 h3 a- [8 P% A
  auto?           ;; whether or not this intersection will switch automatically.
. M/ \! Z* t$ X                  ;; false for non-intersection patches.
$ z/ f- _7 [! z]
, }: n: p' i: t3 n# g0 R% [0 g7 m
9 o$ i- k3 i( A5 H, b7 {7 @$ g# S
;;;;;;;;;;;;;;;;;;;;;;
/ O2 f, E, m# Y4 @: X;; Setup Procedures ;;$ G- Q" C- K+ c5 M
;;;;;;;;;;;;;;;;;;;;;;: M8 y) L( l; y- u; H
9 W, _5 i% B+ x7 y9 A2 }
;; Initialize the display by giving the global and patch variables initial values.
* n% u9 |9 |9 ], z# `/ ];; Create num-cars of turtles if there are enough road patches for one turtle to  N8 f' a3 O. o2 ^7 P
;; be created per road patch. Set up the plots., H7 L* R! K$ b, L6 i
to setup
2 w1 J. Z7 a' a$ h' L& L  ca# s5 X9 Z; w1 [8 H4 P1 p# f" O
  setup-globals/ `( z+ W3 J" V- t' [: }, u

4 S- D% Z5 Y6 h) I  ;; First we ask the patches to draw themselves and set up a few variables! i* G: g; ?# K% ?& f. ^  H
  setup-patches
+ r* y- w5 j2 ^% }3 i. s7 P- X  make-current one-of intersections& |5 O' |! o0 ~3 A9 \$ z
  label-current
4 v: c2 Q5 N, ~4 H5 ]& E# ?. W5 ~3 a+ U
  set-default-shape turtles "car": }7 F& A& c1 {8 O8 [% W1 b6 i) i

$ F& C1 {( a+ b7 K: u: ~  Q0 {  if (num-cars > count roads)4 g' h) D. }  s- L
  [# L3 O, X6 i# _
    user-message (word "There are too many cars for the amount of "6 E/ b3 s; u) A9 F, a
                       "road.  Either increase the amount of roads "/ N/ F" t& r9 p" y: k, ~  b: k/ i
                       "by increasing the GRID-SIZE-X or "4 L. k! G. U/ I5 K1 |3 ?" R0 S" a/ i
                       "GRID-SIZE-Y sliders, or decrease the "
. S- Q: G9 E9 F1 u& {3 o: N- C. a0 v  ~                       "number of cars by lowering the NUMBER slider.\n", j3 V* t! F) Z8 D" t7 Y2 f
                       "The setup has stopped.")
* K8 O0 n9 [0 E, Q9 \. k0 l2 h    stop
2 P0 t3 D* ?; }! r5 b: A& H  ]
+ y9 G4 F# b3 V/ x9 h2 C% Q2 N6 s& v, q5 k, S: Q
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color' [5 Z+ o, K% L! C2 G( A" q3 X( f  v9 Q
  crt num-cars
4 k$ t. W  S% ]  K$ h9 a, D" U  [
1 M! f' u' F& T- t    setup-cars
& g7 \+ D- t* ]/ D1 ^" Z2 t. S; l    set-car-color
- e  n: g& `: ~5 T) ]' _# D    record-data, Q7 h$ ]4 @0 z# k! |
  ]
7 {! J) H8 T, G: H/ M
0 b6 d( H. L$ Y6 G  ;; give the turtles an initial speed, }( H8 g* N' V% R
  ask turtles [ set-car-speed ]
$ d! ^1 W' G2 c, t2 V$ E; J" G7 @9 C3 X& w9 O1 f7 A
  reset-ticks
  ]6 o! l. \" L/ Z  a, Uend
* _& h1 r( r# T9 R+ O1 }4 ^( {  ]7 O' x* q5 r% W: u% Q
;; Initialize the global variables to appropriate values3 M* N$ X6 T4 m; D5 }$ N
to setup-globals
1 U4 B+ F2 b5 C; J/ H  set current-light nobody ;; just for now, since there are no lights yet
# J9 M+ R: j9 d% v  set phase 0/ D* `% ~* b& d
  set num-cars-stopped 09 q! B3 G1 W& `) E8 S
  set grid-x-inc world-width / grid-size-x0 P3 Y; G9 v9 v' {( ]3 G7 v
  set grid-y-inc world-height / grid-size-y1 c' z$ k8 v" K; |' u7 D5 n

8 C6 J; Z( ?8 W, e& v7 N  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
" A( \# A- a% @5 [  set acceleration 0.099
& F. Z+ h9 H6 Q. n: F/ E3 [end
  v- ]1 x$ g8 H! S7 u* O
& H% c2 \+ C# x;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
0 o$ O5 c+ a2 u* V% c2 x$ T2 _  r;; and initialize the traffic lights to one setting" \; D' C8 m# c6 C* ^+ \( w
to setup-patches
# W( i- R/ E6 j: d  ;; initialize the patch-owned variables and color the patches to a base-color" S" G. m. M& o& M( y+ ^
  ask patches
6 L0 Y: t3 |5 ?7 `* \  [
2 a/ D! f  e# g* R    set intersection? false- [) J" {7 G% e6 l' [; u% a3 v5 q
    set auto? false! G9 B( K2 [1 }2 j) O7 f' w
    set green-light-up? true! E+ X! t% G' [7 [4 [7 z7 d( i
    set my-row -1
- j) X% ]; d" A# w    set my-column -1
! f9 K' s" b) }# y: N" O' `    set my-phase -1  |" S& X+ \+ i7 O
    set pcolor brown + 38 N5 }: T) g( ?5 E5 I* ]
  ]' @4 w. k% G2 U2 V  ?# W

$ Q  U5 W$ R0 a& S, j7 [. g  ;; initialize the global variables that hold patch agentsets
! t: F9 l) ^2 ]  N4 _. Q( {  set roads patches with
' |% ?7 e1 w) a% B- w! o6 m    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) {. |% Z  W  L
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 R' t3 o5 |: V4 T
  set intersections roads with
; F5 F  @7 e9 F! v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
! S. U1 T, U& W3 n  `7 y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: j# U  o! u" }4 h: X; p
: E7 Y8 ~2 r% Q/ K' o  ask roads [ set pcolor white ]7 B3 E% e* s7 g( z  ?
    setup-intersections
. `4 q( ]# f1 I, v/ e/ v2 Cend% j+ L. d4 r1 X0 M
其中定义道路的句子,如下所示,是什么意思啊?
& L: h" _2 Y- x6 F set roads patches with' U' R4 q/ w. F7 K4 \
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! [" A$ k5 u; T! W& {) Z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; b3 u5 W; }- u' y8 Q  `4 N
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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