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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。+ [! _/ L3 R7 \1 y$ C& @3 x
netlogo自带的social science--traffic grid这一例子当中,+ N5 @9 ^9 D# ]/ d+ {: I3 ~0 L
globals- @$ \4 }4 W) }* b) Z, t
[
4 ~# R9 e, S+ z* {: n  grid-x-inc               ;; the amount of patches in between two roads in the x direction% S  @; ^& [+ F( K$ X/ R* e3 `
  grid-y-inc               ;; the amount of patches in between two roads in the y direction) X" U# X% ]8 ]! h" ?# G1 \
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if) S$ p; x0 |/ v9 I; |, X6 j
                           ;; it is to accelerate or decelerate( g& _% f  w3 p; ^2 Z
  phase                    ;; keeps track of the phase% c4 \$ z, @4 O
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
; m2 `8 x/ \! S$ m' ^" Y  current-light            ;; the currently selected light
6 ^# S- Y& m, c/ _3 [5 m9 h
8 A  N: y8 K, Q# G: w: v/ F( k  ;; patch agentsets% C4 q0 Z2 a6 c8 g# t2 s5 B
  intersections ;; agentset containing the patches that are intersections8 E5 D, z" ]* [+ ^
  roads         ;; agentset containing the patches that are roads% l6 M( y0 Q3 N; e' W
]
9 k' k( X4 D1 [! a
+ L6 R# T9 P5 }0 l3 Wturtles-own
: C% u" o: ]" A9 k  G[
+ ]; N& l6 j. ]  speed     ;; the speed of the turtle/ d+ P7 p' ^. o! t
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right+ C- c3 ^( m- F, I; N: U( z
  wait-time ;; the amount of time since the last time a turtle has moved& \- c% h  X' ~3 O5 ?
]* y2 H" `6 l( ]4 S3 {0 j- Z
/ f# Q+ ?: l9 Q+ A3 ?: ]
patches-own2 {$ J: t! y. V! \. F
[
; w3 Z6 M& t8 }4 S$ b  ~  intersection?   ;; true if the patch is at the intersection of two roads
% h$ Y) |6 s9 V9 d  green-light-up? ;; true if the green light is above the intersection.  otherwise, false./ _' [! u7 i/ q. T+ ?, r
                  ;; false for a non-intersection patches.
- H" U# g$ k/ P  my-row          ;; the row of the intersection counting from the upper left corner of the" u: {" O/ ^& T) o* e" j
                  ;; world.  -1 for non-intersection patches.. ?* e( z; ?1 \: a! O
  my-column       ;; the column of the intersection counting from the upper left corner of the
  x& c* m* K1 o, E+ M; v                  ;; world.  -1 for non-intersection patches.
6 P; h0 w9 m  Q0 E" S3 `  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
; G5 w: ?) E/ L* r, h8 F, r0 N  auto?           ;; whether or not this intersection will switch automatically.
, K7 O1 f0 g4 R: m1 ^                  ;; false for non-intersection patches.% T$ V: o/ [* z# v7 B
]
9 h' t' T3 ?7 x  K$ V/ p8 c0 s2 E3 p
& W& ^0 P7 V- X/ [) |* Z
8 {3 D  S6 g$ G: q7 \;;;;;;;;;;;;;;;;;;;;;;
1 g% b0 H: S- _* i( H  A;; Setup Procedures ;;
  z3 g" P$ t- R;;;;;;;;;;;;;;;;;;;;;;
; @. C* _& w  L' _+ R
' G2 |4 l5 V  A0 U, ]( X- A;; Initialize the display by giving the global and patch variables initial values.
* _' _$ Y5 j1 p" O$ Y" c; l;; Create num-cars of turtles if there are enough road patches for one turtle to4 L# o( ~0 l8 R9 C
;; be created per road patch. Set up the plots., a' {" ?) q0 `) P- C0 y( ]4 c& q
to setup
+ l2 B$ |6 }; H, X5 s  ca
& }* K$ e5 a- K9 v# B5 }* {8 ~  setup-globals
8 O' P" j" Z) J5 L$ |- P7 Y
/ a4 M" g. h4 ~- N, }# f1 D  ;; First we ask the patches to draw themselves and set up a few variables
( @" t2 y$ E# J. y  setup-patches
+ p7 ?. h; `! ^  make-current one-of intersections. X! l0 _( W! `* u$ l9 F$ i
  label-current9 [' _) q7 a  M4 ?5 Z% _
9 x9 D1 j0 O3 s: `% i4 M
  set-default-shape turtles "car"
0 h; N! n' [3 W2 g% c% Q- r% j# R; K7 y
$ [6 z: a8 g, b3 U  if (num-cars > count roads)
1 ]; T  X1 n' P2 h+ a9 e" A9 H  [
6 A  K2 F2 p' ?$ U. b6 }0 |    user-message (word "There are too many cars for the amount of "7 B: U' c& d* x+ c/ G
                       "road.  Either increase the amount of roads "5 }$ Q* x6 B' a/ k: F' D) }
                       "by increasing the GRID-SIZE-X or "5 F0 ~% E, I4 z3 j; z
                       "GRID-SIZE-Y sliders, or decrease the ", @/ ?) u3 f3 ?# [' C5 N
                       "number of cars by lowering the NUMBER slider.\n"
- C" k! x* z! T5 V7 p9 {                       "The setup has stopped.")
9 J: c% e/ `2 z& u    stop! z* F3 J% e$ ?& N, B8 G8 l
  ]" O3 \" r. h$ T4 i6 J
, o7 M: j( F0 F7 T+ [( \
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
$ q  g) E, i3 p  crt num-cars
+ I6 J" `# j. Y2 K5 [  [( W: G7 l+ `4 @
    setup-cars
8 L8 q6 e, E: [4 o2 t2 O1 U    set-car-color0 p* f1 X+ K8 r; U; c& v
    record-data1 P' g" D$ r. A$ ]0 O
  ]! }& _0 B2 P' `" q

  L% @7 H, W( f, f" s  ;; give the turtles an initial speed
. e9 ?+ N) G1 Y5 I' Y, v, C  ask turtles [ set-car-speed ]
# ?" ?1 N; }$ L9 [& M
* D9 ~8 w, i1 g- {2 l  reset-ticks
5 K% [4 b' @! r0 Yend
9 V3 N4 M& v& j# t! y2 |
$ ~* u% O1 _* s9 O;; Initialize the global variables to appropriate values2 M, Y! u% B0 T+ ?7 @! X0 ?
to setup-globals
+ i: g  O" v) V! j' k* i* s- N  set current-light nobody ;; just for now, since there are no lights yet; ?: U6 q1 D5 S4 ~: z* {; \
  set phase 0$ H& x' N! _5 e& P+ R2 y
  set num-cars-stopped 07 f/ ^8 \6 i! Q/ f, v
  set grid-x-inc world-width / grid-size-x
" ~" Z. t) S6 r, E: S  set grid-y-inc world-height / grid-size-y1 T+ T0 E$ |) N

8 O! l/ L- P5 `4 T7 T0 W: b. z  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary6 _2 k9 V- y6 g/ a9 z9 b
  set acceleration 0.099
1 G  m4 B4 L4 {/ B' V: Aend
, H; k8 ^( s8 @% p
! j! `' t! Q6 o;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
! C' h& s$ A6 K+ ^: m# z( c6 K;; and initialize the traffic lights to one setting1 T* n* ~# G" `( B1 ~5 P
to setup-patches4 e! T! P1 d8 |+ o8 W( Q; Y
  ;; initialize the patch-owned variables and color the patches to a base-color7 U' V0 I$ y; u
  ask patches
5 {, A. }7 a8 M  [
. h5 |0 o/ D2 I. }+ m$ A    set intersection? false
- u& Z, Z+ h( N# F    set auto? false
1 G9 d) C7 N! ?    set green-light-up? true. [! z: A& d# J8 [- X6 H! Y
    set my-row -14 N/ w# r& E2 X9 j- O- u* |
    set my-column -1
- f9 C  T# n# p2 ~    set my-phase -1% o7 u. a& A; T7 b; f) ]1 Z; s6 [
    set pcolor brown + 3. H! m7 f! D7 }+ Q# b( I
  ]: I/ ]7 h  D# k- l1 r0 X

/ M3 t& v1 J7 ^8 O5 d. Z4 m9 M  S3 Z  ;; initialize the global variables that hold patch agentsets2 p9 w- l8 w/ }1 y6 l# h; x3 V  u0 F& ]/ Y
  set roads patches with
, V+ j4 ?- G7 S( L    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 g0 ?( `- o5 x5 J1 ]6 B* I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# i/ v/ L9 l1 n, u! u  set intersections roads with  t' \' ^. ^$ i$ h/ {  h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
" {: t; g2 i: P& Y1 \, T. K# E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 V7 Q; V" d/ q6 ~0 C! X& Z8 v' z/ {
  ask roads [ set pcolor white ]8 C7 [" b: C# c3 i
    setup-intersections
( O6 x. c  Y5 ^/ t+ x) l6 P8 h9 Lend# ^+ e" I" P2 G7 _
其中定义道路的句子,如下所示,是什么意思啊?% {) S: y  g5 U4 }
set roads patches with
1 K" i8 ~. v( X) x    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ h5 u) f# W- T" i' a8 B) y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& y( M) s  @9 r9 ~
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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