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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。
; `' h; s, p9 w  F5 Knetlogo自带的social science--traffic grid这一例子当中,$ x8 u. y) V! k) w: _0 E1 ]- S
globals5 ^7 ^, m0 J1 D) J, [/ h6 Q
[! Y6 ?" D7 _! g! h6 W$ ^1 z
  grid-x-inc               ;; the amount of patches in between two roads in the x direction( S- }9 u3 q6 B4 x2 V% X- a
  grid-y-inc               ;; the amount of patches in between two roads in the y direction4 U' B! \6 ]8 ^( H
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
( W5 S# [6 x' \0 t! A! j+ w3 o2 D                           ;; it is to accelerate or decelerate
- W' g$ d0 P* j% j, J9 Q  phase                    ;; keeps track of the phase
' D, I" B0 a4 w! q4 Y/ j  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure# Y' m/ Z0 F; z& N
  current-light            ;; the currently selected light( ~9 |* z8 {8 J
& }* s) E; [4 E) U% T$ S8 ]9 r
  ;; patch agentsets# J( |* r2 t8 d( m  o2 C, e
  intersections ;; agentset containing the patches that are intersections, D" L( v. L8 ~
  roads         ;; agentset containing the patches that are roads4 q8 d/ G) U& `! U
]
& `' M3 f' w- ]0 T$ i6 b
/ ^7 E$ v# j6 g! Z. {" gturtles-own8 G" u( l+ w3 l, Z
[
. C$ U2 n1 B/ {" T( k  speed     ;; the speed of the turtle
+ o# n4 p* \7 _7 S3 T- P  up-car?   ;; true if the turtle moves downwards and false if it moves to the right6 X# Y' p! Y8 J# |* P: W. J1 d
  wait-time ;; the amount of time since the last time a turtle has moved9 e8 E8 X/ x, b( K9 q
]0 ~0 }; [" k9 ~2 \# V
, _2 M6 Q5 P% S4 n) q
patches-own/ r/ k! x- k; p( Y4 D1 A- c$ u
[2 m  W" j- O9 q8 a0 @5 O
  intersection?   ;; true if the patch is at the intersection of two roads
& o) M' }7 p2 M- G  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
: [& s2 n3 d4 u                  ;; false for a non-intersection patches.3 ~) z7 O5 ?  t0 T6 u  q
  my-row          ;; the row of the intersection counting from the upper left corner of the
4 d/ x7 R" f0 N5 O: x' [8 F, r                  ;; world.  -1 for non-intersection patches.4 q9 a: F: r: d1 R) V/ W8 @
  my-column       ;; the column of the intersection counting from the upper left corner of the
6 Y6 l( ~9 f1 {                  ;; world.  -1 for non-intersection patches.( M4 Q% q: S" |$ s
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
' D2 r' z' I, ~. P' P/ g2 s  auto?           ;; whether or not this intersection will switch automatically.
; y+ N1 K  _0 {0 ], Z                  ;; false for non-intersection patches.
6 O, k: Z" b0 j]5 r; N, v8 |& L& I

3 |' Y/ f9 J" y" `
" @* u' F- X6 e+ w2 n4 N# ]. a8 S;;;;;;;;;;;;;;;;;;;;;;
0 e7 C( D9 {& F( p7 k6 z% I) w;; Setup Procedures ;;& Q  l& E' f6 o# F
;;;;;;;;;;;;;;;;;;;;;;
" A3 u6 n- w( a/ j- k1 u8 R" `) d. Q$ g7 f$ ~, k
;; Initialize the display by giving the global and patch variables initial values.5 B! M" i% |3 ~" P1 U
;; Create num-cars of turtles if there are enough road patches for one turtle to0 m  u/ k1 e3 I: @
;; be created per road patch. Set up the plots.0 k* q4 V3 V" q( n
to setup
3 D$ `1 I8 h, h* C- R8 P3 _0 {  ca8 Z3 M" S) W2 V3 P; c, q! n4 V
  setup-globals/ g: Q1 h, R/ i1 ]

1 u$ O8 I4 O3 E# D* `  ;; First we ask the patches to draw themselves and set up a few variables' X( ]& E, R$ C
  setup-patches+ o, g! [( f! |
  make-current one-of intersections
$ r4 o( ~, t% t2 R2 q  label-current5 |; j9 P1 ~. p5 g2 u
& {$ H1 V* a7 k. h% A) e7 \1 r) m3 M
  set-default-shape turtles "car"$ L" C7 i: q7 J" E

1 T& `6 `' H, Y2 z( y( K  if (num-cars > count roads)
3 B) g, w0 d2 }' c+ u6 @9 p/ W  [
% _# I3 Y3 M  s3 ]  F    user-message (word "There are too many cars for the amount of "
3 A# W. u2 q9 r. f) v                       "road.  Either increase the amount of roads "' r# p0 w8 Q7 a- @
                       "by increasing the GRID-SIZE-X or "1 ~4 P3 O% G2 @9 W  a- {
                       "GRID-SIZE-Y sliders, or decrease the "
! s% k5 v& L4 S+ C7 E                       "number of cars by lowering the NUMBER slider.\n"& B  j7 ?8 ~$ n4 R% {( i: S
                       "The setup has stopped.")
+ X9 y# R- W" N0 d5 z+ e+ K* v( y    stop$ B# l3 f* F+ G
  ]
6 I% W  R" `% A" l1 o2 ~% a9 f8 G/ z( ]' R, e% l
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
: {; e7 i$ C, W& ^: o  crt num-cars: b& E/ V; N4 F4 a- H* v" u3 X3 @
  [
& Z5 C! Y& I7 x7 N2 S7 L    setup-cars
2 n$ R* H4 l% y    set-car-color
/ ^3 B4 u7 I7 d( Z" L    record-data
: \# h0 u  `( C. j3 }  ]# k" y. j$ I4 T0 j

5 C* s& _7 {; e; _/ k  ;; give the turtles an initial speed4 `8 a3 }1 {9 {
  ask turtles [ set-car-speed ]
' u3 }; t0 o" w' Z, b$ Z: i" ^  I: O) l+ }- ?$ t; o- Q0 d
  reset-ticks* V# R  b8 U9 C4 p: n
end
# W5 j( t# R7 o6 r7 t/ t- N- a2 W$ a6 I8 p
;; Initialize the global variables to appropriate values
) f' D: O- Z/ h& y6 P" b6 Z0 wto setup-globals
, M: V) V2 Z/ ]7 b; s  set current-light nobody ;; just for now, since there are no lights yet" y3 s$ E+ {+ h9 e; [: j
  set phase 0, D, B  c( P/ {' V9 d
  set num-cars-stopped 0: I) F+ I) ?+ ?
  set grid-x-inc world-width / grid-size-x
: z. H# V& C7 W# Q$ k* _7 ^  set grid-y-inc world-height / grid-size-y% |' @: M4 U" i; s4 {& y/ g

1 l1 K; H1 ]1 e3 ^3 W# J  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
9 O# O/ _* S7 q5 D+ [  set acceleration 0.099
2 m. \' @& ^4 _/ b. ^end2 I% K& d( y, C6 r) Y& N2 {8 C

% S5 V# F: \" q3 Q; G+ f;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
- v+ O9 g# C6 J" r! Q9 r" T;; and initialize the traffic lights to one setting
9 l; e) x9 U* P0 E0 x9 Z, f8 Sto setup-patches
5 L4 H% S0 q; }2 @) E7 U9 X/ y1 x  ;; initialize the patch-owned variables and color the patches to a base-color$ Q8 D+ K$ f' e: H
  ask patches; T' F2 Y+ t1 u& E  V) W3 z
  [" F; D, S+ p# x0 `3 ]- b9 j- G" g
    set intersection? false
/ B' Q4 y% t5 }+ p    set auto? false+ v1 i, p( G1 Z5 j
    set green-light-up? true8 N; t  ~  G8 C& }0 M5 o
    set my-row -1
/ t1 F- S- ^1 m4 l) ~+ |% z    set my-column -18 ~, j0 v; k: ~
    set my-phase -1
1 p4 m; m, Q9 A- p: P6 Z    set pcolor brown + 3
( r' g3 X- k( _4 U) L8 @8 Z  ]
; H4 T. [6 G# b0 C+ H; ?1 q3 W6 y9 v6 i: V6 D0 _
  ;; initialize the global variables that hold patch agentsets4 j  ^+ j8 U$ t0 s! U, G
  set roads patches with
5 P2 n* Q  T9 C( C: n$ E! ]0 f2 I    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ [: D8 U' V7 N6 H: ?1 ~
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ l- Y; D* k! C) n  set intersections roads with
' }* o7 ^* V, E9 T3 X" j: `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
, B: R. g4 Y! I" C1 j0 P- E  u    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 @, P* W- S9 q6 A- z1 S5 O3 _

' @5 O4 |0 e* y2 x, Y/ F  ask roads [ set pcolor white ]
- N9 m/ B/ Z) z3 P    setup-intersections& n8 Q( k1 |/ s2 c% ^$ c1 S/ b
end- j3 q" f5 x, {. ~" W& u! J
其中定义道路的句子,如下所示,是什么意思啊?
7 ?, p5 y% m2 g. i+ G8 J% D: H set roads patches with- m3 }4 U# o3 e5 @4 u  }: A5 R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% E& E  @2 q) t
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. c3 x# r+ K# v' P6 O$ G! r
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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