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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。
+ I$ s3 j. e! c% _! d6 _$ hnetlogo自带的social science--traffic grid这一例子当中,
. C* R% }( D& x3 k- ~globals( D& n" J0 M7 U
[
) g) a) l. |0 l( M* M  grid-x-inc               ;; the amount of patches in between two roads in the x direction  f7 ^8 |1 ]% w" |, O4 f- w
  grid-y-inc               ;; the amount of patches in between two roads in the y direction0 R. l' ?' _) }
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if! x+ o  g0 y6 U# Z" i6 m% ?; }/ N2 _
                           ;; it is to accelerate or decelerate
- j3 `: {9 z. l+ y+ @$ |3 M  phase                    ;; keeps track of the phase) @$ h; g$ R: n" f% J
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure3 P( O1 C* C0 o6 h" \% F0 u
  current-light            ;; the currently selected light* k2 L/ U' h) {) {% H: D9 \

% y1 |* W) r- K) S# {  ;; patch agentsets/ C- k; M: J* T4 V1 @6 t
  intersections ;; agentset containing the patches that are intersections- O* e! _# v+ P; \+ ]5 d0 s
  roads         ;; agentset containing the patches that are roads
' E! z* b* \  F6 i]
" `7 G: H9 c7 J$ ]5 \' d
) R4 M% i5 C: @! b/ C  cturtles-own% P2 o  D4 ~! c6 i& T$ a6 t/ M
[
8 b8 k4 J$ P' j6 y' E) l% c  speed     ;; the speed of the turtle
/ X- o# p4 k5 r; ^  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
- w+ b$ w% C6 r- c# n6 `# f9 t  wait-time ;; the amount of time since the last time a turtle has moved
+ f3 B7 `3 R( n6 K' }]
3 P$ T; z  J3 N; D. W0 F9 o2 L% B9 i4 a) B2 M* ~. D, u
patches-own. i7 T; E% Y  {/ E% v9 K. @
[
3 Z$ j+ R  E- S9 ?  intersection?   ;; true if the patch is at the intersection of two roads
3 k" K0 b& M, V* y, C/ z( b  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.0 Z* q. O& v; O. r: ]
                  ;; false for a non-intersection patches.
# y, O4 z( b$ j  r; |$ d6 [# P  my-row          ;; the row of the intersection counting from the upper left corner of the0 D0 K$ P/ E  F; u. r
                  ;; world.  -1 for non-intersection patches.
! c( S1 `- F, H5 i) Y# y  my-column       ;; the column of the intersection counting from the upper left corner of the
* R4 M" f9 ]0 \' C# q2 k; ]) h                  ;; world.  -1 for non-intersection patches.9 q% `' ]; C+ P' R
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.4 Z( |2 X' U/ ?) Y9 l
  auto?           ;; whether or not this intersection will switch automatically.
; p- Z9 h/ j* Z: S2 d& `! b                  ;; false for non-intersection patches.3 [+ O3 u: _* ?
]
8 l( ?: Y3 F5 F  T7 a4 H" o) S0 |2 E1 F# i6 ^0 a" n& z8 ]: X. A* o

$ w, v- X. P* \2 ?; P7 x6 a: @;;;;;;;;;;;;;;;;;;;;;;& U  \: d& d! q% b0 b5 r" {/ c
;; Setup Procedures ;;
- b( ?* R2 U/ s7 f1 o7 N;;;;;;;;;;;;;;;;;;;;;;0 {' ~" P8 l# ]+ z* ~

6 y0 J4 S3 `" Z; r;; Initialize the display by giving the global and patch variables initial values.
# Z% l' F) V4 ]7 P3 ?6 u- o8 o$ P;; Create num-cars of turtles if there are enough road patches for one turtle to
! ?) p9 h; [! ?; U1 ]5 N;; be created per road patch. Set up the plots.
2 h+ k/ h7 M4 B& g' ?0 }to setup
1 r$ t# ^2 {; z  ca
8 B. L, f) l  ~3 r# u  setup-globals. [* {# S* n6 [) C& v. b
! {' Q5 |  o8 e! ]  W8 b
  ;; First we ask the patches to draw themselves and set up a few variables
2 {3 W+ S7 X$ N1 a! M% n  setup-patches
4 ^% w. G' v) E, j; _  make-current one-of intersections" H2 m6 I1 U3 X! t! M
  label-current
$ l' G! \7 U& P. r6 E2 T
) \0 J# F) g# G% t6 k: f9 Y  set-default-shape turtles "car"
0 p- G/ R) X# [' u6 h# s9 K2 l! }
* [+ B; L+ ?' G  if (num-cars > count roads). S& Q5 p6 c+ x" [0 h- }' c1 B( d: ?
  [7 N, b' X5 @, `
    user-message (word "There are too many cars for the amount of "
, M% v9 t( L* |7 [5 @4 r6 t- G                       "road.  Either increase the amount of roads "
% v4 D1 J0 [8 f6 w& X7 ]                       "by increasing the GRID-SIZE-X or "
# z) M. V: }$ U# I' z                       "GRID-SIZE-Y sliders, or decrease the "% B/ v8 h& z2 f/ h" B
                       "number of cars by lowering the NUMBER slider.\n"
9 O* c: F1 `# B& b                       "The setup has stopped.")
4 e( i7 [  L8 O! e' \    stop
# e: ^! Q8 A# J) [  ]- j3 t. @) Q2 ~3 O; B

$ b6 ^) e) M2 t0 @; W1 n2 t/ W0 }8 {  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color% o9 i+ Y  j6 Y3 j6 V8 x  Y
  crt num-cars
9 S$ }, A) ^. \6 [3 D! {2 W" [  [: d. e) P6 L. _2 D8 ?$ b: |
    setup-cars+ e5 S: w* E+ h$ j
    set-car-color( R( b, H0 ^. R- t! S( _! U
    record-data# r# _: d8 G7 F
  ]
! A& s5 k+ r5 r- k
. ?: N9 T  B3 z  ;; give the turtles an initial speed1 w  w* s4 M% O
  ask turtles [ set-car-speed ]
* h, R6 P0 H+ i/ B& v% Q# _8 {/ o" c$ g+ V3 J( Z0 Q% E
  reset-ticks% N' G4 J# ?; x7 J5 _4 Y: Y8 Q. a
end
, F! x+ n6 q* y7 b$ c! Z3 i( u  d0 ]; o- M
;; Initialize the global variables to appropriate values
: n, n- G+ g9 V* }! {* _% eto setup-globals3 A$ M! ?8 |- ~3 y/ I2 L
  set current-light nobody ;; just for now, since there are no lights yet/ w3 V) _8 U7 M. I
  set phase 0
2 A# `8 a* @6 ]  set num-cars-stopped 0
8 W5 Y/ a% i4 w8 _$ I; p4 J) _  set grid-x-inc world-width / grid-size-x! z0 R3 @+ R; _- `$ L  o2 a9 Q
  set grid-y-inc world-height / grid-size-y! Q* M& \# ~0 W) [# H7 C; a1 i3 |

2 A* z6 t7 c$ d! j/ W+ q: d# G  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
) a% Z8 I; I' U7 I) {6 M5 |! t# F  set acceleration 0.0997 U; I1 e, ^& }2 T% B
end
' o8 r+ [* s3 F, u! l! f9 i
3 O8 Y# }- b6 E+ @7 U" E  J+ w;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
+ a; H8 m9 s! x  R1 ]5 p;; and initialize the traffic lights to one setting( @! H$ p. u9 c( E3 z/ M5 O& a3 h
to setup-patches
( B7 w% q* ^7 x* R) o! Q  ;; initialize the patch-owned variables and color the patches to a base-color) a& _3 U9 U! k" H
  ask patches# W1 R3 }9 E+ w: @
  [
/ m: |0 U$ a8 K, h    set intersection? false
) P! P5 v# P& B& q2 @    set auto? false
( a( y; p3 g+ x4 V  p    set green-light-up? true! d1 j2 N, t& c/ O" {7 j
    set my-row -1: ^- T6 @% w7 v9 Z# `
    set my-column -1
: s2 ?# o4 c! Y    set my-phase -17 y" h2 Y/ q; U) l+ j3 n
    set pcolor brown + 3; @* j+ g) e  j  P8 z& o; f
  ]
5 B* {( L; L  G; B! ~4 M) ]) d. @8 Y/ r, @+ Z! a. r1 {  P
  ;; initialize the global variables that hold patch agentsets* n$ g4 O" h& v$ a
  set roads patches with
: M) r( R( X) D6 l2 ^4 m1 r0 G- C    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 ~/ J9 ^" ^# M2 |  _! I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 H# W4 Q0 [; a8 m9 o1 O
  set intersections roads with
5 Q1 e6 C' t) ?; t    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
- W* e( M& }4 \% }" _) d8 U$ r    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" @4 k% h" {  r/ m  u( C; H6 d  r
% q. k6 W' G3 r  ask roads [ set pcolor white ]
. h& C) ]3 \* `) T- H; v    setup-intersections
- n" [0 z/ K7 d9 F8 t* J5 Rend
* M& O/ i2 n; j8 f9 o; o$ n其中定义道路的句子,如下所示,是什么意思啊?5 f$ d9 r  G6 o' N$ G
set roads patches with: I% M: Q+ @1 Z" Z9 J9 Q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* Z4 A5 Q: E5 b! D+ v; G$ P    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" k+ f" r. P% ]! L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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