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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。# \( o' r& b( y& ?" J5 {9 q5 z
netlogo自带的social science--traffic grid这一例子当中,  K9 q, a+ z  v1 h9 `( l) p
globals. S! O" m4 I" T) q6 n
[
) z9 `/ `# T! A; C$ K1 D  grid-x-inc               ;; the amount of patches in between two roads in the x direction
. ~" o8 B7 T# N  grid-y-inc               ;; the amount of patches in between two roads in the y direction
7 b  _- x2 i" C4 Y* j1 p  acceleration             ;; the constant that controls how much a car speeds up or slows down by if9 {3 h- B; u/ Q8 v3 I
                           ;; it is to accelerate or decelerate, m2 ]# }  r' o8 i- E0 N; W
  phase                    ;; keeps track of the phase3 Y& `/ E3 u& A
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure7 O) J0 r& W9 o6 o. D
  current-light            ;; the currently selected light: f# E* m- }! i! ]- y" |3 `1 J

8 k' c5 f0 A. O+ C  ;; patch agentsets& P4 c) P6 ?6 k  y5 J0 e" t
  intersections ;; agentset containing the patches that are intersections
0 ~* F; H! S- `/ j  roads         ;; agentset containing the patches that are roads
1 Y9 E2 o7 p$ _# d  ^& N]; c* O) E0 ~4 i) V
% i" ~! t, ^6 s: X" t6 Y/ x
turtles-own, n* `, q7 N' T, U0 t8 d6 @) m
[
( `" R1 q5 k, n  speed     ;; the speed of the turtle
- |$ y: B! E1 E  i  up-car?   ;; true if the turtle moves downwards and false if it moves to the right9 Z  F/ a" T) R/ h
  wait-time ;; the amount of time since the last time a turtle has moved
+ s; ?  l( Z, V) H+ ?2 W* {: d]% b/ d  s8 y4 e( _# T' t- e$ @; Y0 X
6 p3 p7 A% g; q- B4 {0 |+ u
patches-own# N" s' @; y# |  k
[
( y7 N( ^4 L8 x9 Q  intersection?   ;; true if the patch is at the intersection of two roads
8 r% Y$ F# H$ g  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.8 F! t/ P' v8 F$ J- f
                  ;; false for a non-intersection patches.$ Y! [1 Q0 \3 d) G0 F$ C
  my-row          ;; the row of the intersection counting from the upper left corner of the3 F/ W+ S% p, n# j  g. q6 p
                  ;; world.  -1 for non-intersection patches.
( Q, u+ ~1 d/ t( o% ]  my-column       ;; the column of the intersection counting from the upper left corner of the4 B+ ]8 R' \" O1 m* O
                  ;; world.  -1 for non-intersection patches.+ V; l# I* _3 m4 u( i; `
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.$ z8 `# T4 A: h* t$ p' j$ {
  auto?           ;; whether or not this intersection will switch automatically.7 L# M) H, s7 j1 |( Q
                  ;; false for non-intersection patches.* `4 F% D! a- T$ R
]
9 K5 N, m9 t( f  ^! a
( j$ U/ ~" a7 Q1 x" T( X- d0 k8 Q; v; p8 S3 ]2 C
;;;;;;;;;;;;;;;;;;;;;;
# p9 K6 j! K- o  M3 \$ O;; Setup Procedures ;;3 @% K& P( x# m2 r9 K/ z1 E5 G7 ?
;;;;;;;;;;;;;;;;;;;;;;7 X9 n1 C9 ~) ?4 |/ b( C9 q4 N
' v) E% }" n; I3 ?
;; Initialize the display by giving the global and patch variables initial values.
+ ~: P! t" i' t;; Create num-cars of turtles if there are enough road patches for one turtle to* v8 b8 F  R( g( t0 C
;; be created per road patch. Set up the plots.& Q7 o9 `0 ^1 n! v
to setup0 x4 ?# }, H9 g) M7 w1 n; \% L
  ca
/ Q0 r. v& c1 q$ m4 I5 u  setup-globals9 j; ^+ l6 x4 E2 C+ r
0 E+ K. h5 A5 N) Y1 C( |# m$ l7 r
  ;; First we ask the patches to draw themselves and set up a few variables, ?+ V1 r* k0 R
  setup-patches
5 @2 c3 d) |$ e" K  make-current one-of intersections2 G6 Z' ^  M" H0 b6 X* p6 h
  label-current
7 X" e' R. G/ d
+ {- X( B7 F1 a2 E! C: z3 v  set-default-shape turtles "car"
) f2 Y2 H: Z# R. n% p/ J! S' w2 c+ F" b! r  M3 Z3 k
  if (num-cars > count roads)  d3 s7 _: }; w7 [
  [
6 X# C! |7 m: @    user-message (word "There are too many cars for the amount of "& Y3 |0 k( O; }8 Z3 G! e) b& Y
                       "road.  Either increase the amount of roads "
1 h5 {* u4 g4 J8 y* q5 n3 |                       "by increasing the GRID-SIZE-X or "
$ J. v" E- ^! E                       "GRID-SIZE-Y sliders, or decrease the "
6 a3 R* g3 O6 r  x' n) c2 R3 `                       "number of cars by lowering the NUMBER slider.\n"+ W# W" @$ v# d; Y+ P
                       "The setup has stopped.")
% P4 o7 B& ]; p    stop' e9 x8 P7 v" C9 n9 t# ~
  ]
' [  R( l" }# D5 b( [# |9 l' F5 I/ G- J/ b1 Z
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color; C- ]% w6 A* A6 ?2 f0 t
  crt num-cars
* V4 l, P+ ]6 u' c. S6 O6 H  [
3 d0 E5 U4 b% }8 F7 t* N& q    setup-cars% l, V3 h5 y3 ?! d& c
    set-car-color+ B& n$ r' l1 G( v$ }( H
    record-data/ K0 J7 Q# z! y- D) J, F
  ]1 |: Y* `, ]5 U- x- B1 P. k' C

* f3 I4 e+ V& Q- {! M  ;; give the turtles an initial speed
. ]5 s! ~: N$ |4 c& b; e& h  ask turtles [ set-car-speed ]
! }. U  w  B) {! K# Y7 w. d/ k" `$ J) q0 Z. v
  reset-ticks0 H5 L5 u0 @7 F  Q9 s
end3 ?$ d+ \/ X  X" R( P: ?# V9 d

1 o1 N1 f1 E* ~/ q- J5 s8 _7 U;; Initialize the global variables to appropriate values
9 M0 V6 e) s, K7 l: e# Hto setup-globals
7 C, F- `" e- b5 O  set current-light nobody ;; just for now, since there are no lights yet$ C2 V9 k5 ^# e! Y
  set phase 08 o4 K, e% ]- m9 a8 w7 [
  set num-cars-stopped 0
& W4 J0 z4 ^" U$ @" a  set grid-x-inc world-width / grid-size-x
0 G; M6 Z, |4 |0 @  set grid-y-inc world-height / grid-size-y
0 t9 R  w- b' Q) L1 P9 n: X, w9 F1 s% {8 `9 `% S6 X
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary6 n+ y& F; M1 b7 }* H/ t% \' c
  set acceleration 0.099% R% o8 n2 B. l% F0 ?; h( I
end
2 [) z! A! ]. i5 x. s/ y0 @7 `. a! {/ Q  D6 b. X5 D
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
9 A* F, s; X: P# g& Y+ }, J/ P8 p;; and initialize the traffic lights to one setting
; l7 n5 U+ g& I7 D; cto setup-patches
5 V. a1 R, e3 s8 F  ;; initialize the patch-owned variables and color the patches to a base-color
) A5 _4 a+ K5 y5 q0 K  F! z  ask patches
7 q! s2 l, W0 j5 f8 Q% i  [+ a. ~! `8 r5 r  k9 N
    set intersection? false
, p5 D: B# ^+ K$ ?/ b+ v    set auto? false
- V1 A1 W, ]+ i# F    set green-light-up? true
. m+ c' Q/ Q( i- n- B0 p: c    set my-row -1
% X  {2 q, M4 Y    set my-column -1
0 c; `- T/ t+ X4 D    set my-phase -1
1 x) V  F+ U3 S. `    set pcolor brown + 3
1 L" v2 b6 R/ b/ ~. P0 W, o, n  ]
. [3 a, w" n& W9 E* C3 i
/ j, |9 z! o! h9 T; I/ V  ;; initialize the global variables that hold patch agentsets
* @( p5 F* S, \: g; p& b4 r  set roads patches with) v4 t% Z# V# m* _6 Z/ A1 B! y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 o% x( f) |; h( S
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! Z* Y9 U7 a) A! d, y  set intersections roads with
# K0 s' X5 z; G5 T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and8 G9 @, @( Q" l1 j
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 c7 L( \- w7 J2 S# q5 [- N
  R: h0 k0 O+ B
  ask roads [ set pcolor white ]; v5 I% d6 ~6 @# _
    setup-intersections
( H2 y0 I  b) a- @& g* `% F8 kend4 |$ v$ ^6 M  E5 s! }
其中定义道路的句子,如下所示,是什么意思啊?) f& J' `6 y% d* n# v
set roads patches with6 Z) N$ v% H# F" M: O* l+ r! i
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ X, @  G$ K( D5 `  A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; `. b" C2 t. ?: o: t: Q8 ?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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