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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。0 V8 k3 i9 h9 I5 ~- S( ?2 `5 d9 N$ q4 S
netlogo自带的social science--traffic grid这一例子当中,
7 y3 S4 v/ W/ ~3 ^( \globals) }  E9 |; M2 h, g6 @& Q3 C* i
[, p9 n# x/ i! |& w# q( w
  grid-x-inc               ;; the amount of patches in between two roads in the x direction1 n3 `8 Z- q2 r7 c6 [% O
  grid-y-inc               ;; the amount of patches in between two roads in the y direction9 m# D  F$ ~2 F, R
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if) }9 r) F; Q, }: P  S
                           ;; it is to accelerate or decelerate
& k; g1 Y" f: d0 }3 |  phase                    ;; keeps track of the phase0 j4 G& F* s/ P# L2 B  S5 p: k
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure# D6 ]5 [7 o) B5 r9 V# b
  current-light            ;; the currently selected light
' I/ W7 }' E* t# B3 }1 P$ |
' M3 P( x' d5 k' i, r2 `/ Y  ;; patch agentsets
% o, H$ V( R, P6 j  intersections ;; agentset containing the patches that are intersections0 p# p  C; T. Z$ ^6 H
  roads         ;; agentset containing the patches that are roads
8 \- M7 l% m5 t2 n4 R: [# C]! @+ i7 P! L% q% |' \

/ s3 v$ S- a( q/ Zturtles-own
. y* M. {6 a% ^% G: p[
0 c3 `) @: X: n% J  speed     ;; the speed of the turtle
! v% w" ~) f. s1 G  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
2 ?  a8 b% r- V: p  wait-time ;; the amount of time since the last time a turtle has moved! E4 W0 v) L0 A4 {* f; {
]' `8 k3 v" `: X) ]" _

) U) X# q8 V0 |. kpatches-own& L3 R% a; j( U" f) T
[
2 w: J" B! f( P6 c( j# f  intersection?   ;; true if the patch is at the intersection of two roads. o1 S/ p, F2 q! O$ L2 b+ E
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.. ^, @# T6 h; U- }$ U
                  ;; false for a non-intersection patches.
! f1 b+ j" N5 b* ^+ R  my-row          ;; the row of the intersection counting from the upper left corner of the
; i: [5 c. E: F$ O3 h! n                  ;; world.  -1 for non-intersection patches.  K7 _1 d0 i, b  D
  my-column       ;; the column of the intersection counting from the upper left corner of the
7 |# ?& ^9 Q' j. R+ t                  ;; world.  -1 for non-intersection patches.* T: g5 C8 ]1 n% ~5 a
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.5 b7 Q' b0 J' q+ [% n$ _$ M
  auto?           ;; whether or not this intersection will switch automatically.
( s. g4 @% O7 J; z# w2 j3 g6 ]  g                  ;; false for non-intersection patches.$ a5 w) ?' _# d  [4 l4 ?& b
]# h' R. S$ W' O$ A% T( _( o' g
0 I4 b! c/ K2 Z& l
& W+ |, w  U- F
;;;;;;;;;;;;;;;;;;;;;;
! _; f( i3 i9 {4 O9 @' ?;; Setup Procedures ;;
) g- _5 Z8 ?6 a7 A/ e;;;;;;;;;;;;;;;;;;;;;;! t! o0 w2 D# b! L  i, {1 {# ]; ?

  A3 }4 {% D3 \9 C- l2 M. ~+ t;; Initialize the display by giving the global and patch variables initial values.
( K: q3 ~1 E9 v5 B;; Create num-cars of turtles if there are enough road patches for one turtle to& o5 _  l0 Z, B. _
;; be created per road patch. Set up the plots.+ I9 S3 B4 m+ a! p/ ^
to setup0 b* w/ z: `. x* z
  ca' C# N# s' A. ~- ~" N9 X
  setup-globals; u- W& z2 u, b
' N1 Z# n( g9 r6 G; W0 {& Y
  ;; First we ask the patches to draw themselves and set up a few variables
$ i; B4 A- ?* l5 Y( {0 o5 K3 Y  setup-patches" y3 o  o3 z2 `6 J: I! o
  make-current one-of intersections
5 R: ~" l# l$ H9 a3 t) y- j" t  label-current' L: v8 y( ?' i% C
! i% k7 f6 J! }# u+ T  Q  P
  set-default-shape turtles "car"
( U+ {; D' T- E2 {4 Z
9 `3 R2 B' x* I2 c  if (num-cars > count roads)1 L( U. v% @" Z8 a& Z* w) G
  [* J5 w; H, ]( Q4 Y, `. v. w& n: `* J* q
    user-message (word "There are too many cars for the amount of "4 z: A8 C/ a$ [- T9 h
                       "road.  Either increase the amount of roads "
7 _5 t5 z3 M9 L                       "by increasing the GRID-SIZE-X or "
* k8 H/ }6 X* T7 _, q& ]6 ]                       "GRID-SIZE-Y sliders, or decrease the "
+ U; [4 k# W, g! {                       "number of cars by lowering the NUMBER slider.\n"6 S& s. m/ L  V0 {5 I
                       "The setup has stopped."), _8 b5 i0 @! k) H7 X2 S" E) D
    stop# W0 o) M5 d' _7 H, u
  ]
, r- m8 }  I$ {! t- X2 \( u  H. P
+ w* ?4 B( v( `4 Z: g  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
" U2 H. M+ W. w) b  crt num-cars
4 z9 {5 J+ c9 Z& |: l  [
" |% z; J. i. c) _& i    setup-cars
! T; w3 Q6 G  K, ^  b: |    set-car-color, x+ K- K; ]: Y: A
    record-data% ~/ ?& `+ [0 q( r* A
  ]9 G, m9 W/ ?! G4 u# C+ p' V6 r4 E

' Q1 v, s+ O9 q$ E+ ^$ d: l  ;; give the turtles an initial speed
+ }& _& g  P8 B0 ^" b, t" P  R  ask turtles [ set-car-speed ]! P& e1 T5 p. C! L1 r
8 X  N. \0 n6 i3 [
  reset-ticks
3 V0 m$ W/ |) t, vend/ K& N. O  S# ^, S0 y: w

# c0 ?! R$ s" j;; Initialize the global variables to appropriate values! Y) I" I8 a0 _. T9 G
to setup-globals1 Z) c) w7 f( j3 O: z
  set current-light nobody ;; just for now, since there are no lights yet
# P# m+ X9 i! Q4 d' I  set phase 0
# ]  \  ?1 f0 f9 [# {  set num-cars-stopped 0
$ I/ I$ V2 h" A) D* {+ h  set grid-x-inc world-width / grid-size-x
2 i+ n. S* V0 k' R3 q/ ~  set grid-y-inc world-height / grid-size-y
3 N; G0 ]' ~, w6 x& @0 U4 h. m
6 u( o- i8 Y8 p5 k, s" {) i; G* x  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
" q! _/ ?. S# K; X  set acceleration 0.099
& N; f4 K- _1 B, @% Mend
% I% X" p: p  n* U  r: s$ M* @
. B' e. J- J0 Z& q/ \; B;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
9 Q& }6 H0 |! p, m6 C;; and initialize the traffic lights to one setting
9 t* B( }- h7 W. h: v7 wto setup-patches2 ~% _. k; g: J! [
  ;; initialize the patch-owned variables and color the patches to a base-color
" p4 i  B) @7 J4 e  ask patches
: J% _% o, x& y+ {! d" C8 V  [2 \9 l* _2 p7 u% e: t+ ^
    set intersection? false$ I! x. Y9 u. h2 r1 P
    set auto? false7 c6 s! X: g. _6 K& G6 ^
    set green-light-up? true( z  V4 o1 P& n2 T% M# `
    set my-row -1
6 S( S: y4 a& R% E8 R$ e    set my-column -1
2 j1 a$ `( N7 X, h, B  N, o' k. m    set my-phase -1' `2 b( e3 c- D& Q4 M5 U( J  ?
    set pcolor brown + 3; ^% Y# p' D! F' S' w7 [7 Z
  ]+ s5 r5 C6 \5 `+ T* Y2 e
+ K& R2 x+ m4 A) b
  ;; initialize the global variables that hold patch agentsets
; e" X0 M. C0 S  set roads patches with
0 |* d9 U1 M3 h" }' L  E    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( ^. @0 ?/ `8 \  ^) ]
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ l# C0 p* b/ Y: C  P  t9 n  set intersections roads with' E) i0 b' E- Q; R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
& z, w( T& |1 b: q2 b* g4 w: J    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; l( u) V4 F2 V" L* V, {5 ]% X" l, `# s
: `' e7 D+ @, a5 k
  ask roads [ set pcolor white ]8 L/ }! p$ {/ U
    setup-intersections
- V: _6 u% }/ h- l4 a8 u6 tend
; F$ [2 s, W# L, F$ Y  }其中定义道路的句子,如下所示,是什么意思啊?
1 W( X6 t% K$ g4 U( D- P set roads patches with
3 m' T# w. q+ h3 e, d) c5 e* W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" o  ]% D. `9 [7 f9 ~    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 a; q1 f0 w8 ~# c" `7 d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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