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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。& o7 U/ M- O, j% h) j$ ~& J* S8 J/ R
netlogo自带的social science--traffic grid这一例子当中,0 J; L7 [1 }. b' N6 }: t' a
globals% ?* d$ J1 B. I# p# H( j
[' d, b- E  p9 O7 e) t
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
! p& P. S3 a- O$ n/ ~  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 O0 q" U4 o2 ]# y  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 }9 F+ S; s* W( R8 H2 p
                           ;; it is to accelerate or decelerate0 i- N7 X& ~$ d+ f; `8 C
  phase                    ;; keeps track of the phase. ?# T; S8 R! z# X, Y7 g  _
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
1 R$ y9 V0 U+ J  current-light            ;; the currently selected light& T+ T7 N7 s+ G, I% O$ `+ @$ k2 C

) a6 q' j& r+ d  ;; patch agentsets
4 j4 k( c) G  }. c1 H) B  intersections ;; agentset containing the patches that are intersections  ]4 P- z. K* P
  roads         ;; agentset containing the patches that are roads
7 e* |7 H7 c( F) `0 w8 q]& Y5 e$ C2 B3 ^3 |8 `
- `$ T# `" I7 A  d4 Q" \. Q/ h
turtles-own4 d4 X9 y9 h5 U* R& p7 H
[
+ @, s# N4 z1 D  }. U( f  speed     ;; the speed of the turtle; g' ^3 d3 \! J/ m' a- x( G
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right9 k0 E3 @5 V( i# O; b
  wait-time ;; the amount of time since the last time a turtle has moved
( T( R/ S5 h  z/ r% d]3 _( D) C/ v3 b  \- S' {1 Z
3 X9 i, }! F2 {+ N! o
patches-own
2 J3 Y0 T" u! {. Y/ U+ S[
/ K/ @. K! v0 X! b  intersection?   ;; true if the patch is at the intersection of two roads# ^+ u" M' J+ m, R7 H
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false./ s- {; A) w9 ~, i8 T
                  ;; false for a non-intersection patches.
- C4 h& O9 t) o% m4 O* j( P  my-row          ;; the row of the intersection counting from the upper left corner of the
* C8 t. |1 m! r: V/ H                  ;; world.  -1 for non-intersection patches.! g2 Z% i7 k3 [, _, ]  l1 m* @
  my-column       ;; the column of the intersection counting from the upper left corner of the* |. o: R/ S" _4 o
                  ;; world.  -1 for non-intersection patches.
' n, T) b, b  r; C% M' M  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.9 ^% j0 @" I; k$ f7 A3 X' c
  auto?           ;; whether or not this intersection will switch automatically.. Y0 j, Q# ?* m4 p5 b. v$ G
                  ;; false for non-intersection patches.0 f. p8 U* ~, S: A6 X* u8 A% Z( H
]+ `; h& T" |( U# A$ S8 l! m% Y

) n, [* [! @7 h- E  I# [- g( Y
7 _5 v9 `, p- |2 L4 N;;;;;;;;;;;;;;;;;;;;;;: H- N& p! o$ o+ ^9 T  e6 H
;; Setup Procedures ;;/ d$ H; O( P/ Y* S8 X
;;;;;;;;;;;;;;;;;;;;;;6 Y6 j# B% M. r% u
( P8 c# Q% I, }9 r6 O
;; Initialize the display by giving the global and patch variables initial values.
6 }. |; _& @+ l; i' X& A" O;; Create num-cars of turtles if there are enough road patches for one turtle to" \$ j; T1 d: X% G3 `0 l  d
;; be created per road patch. Set up the plots.
  }$ _6 i' E, a3 q0 K2 E+ Sto setup3 R1 K3 q( m0 K0 d) C' j
  ca! g3 p( U1 z$ j2 t, j* F! F9 t
  setup-globals5 ^+ B1 J* v% ~: V' ?: d7 @. M5 \3 g

' K1 d: k1 k# f  U  ;; First we ask the patches to draw themselves and set up a few variables9 U4 U: W/ w, O% T/ P+ j% J1 u) l
  setup-patches
+ G7 A4 \' V. _  make-current one-of intersections- J9 ^) j8 ~' f, R; ]
  label-current$ Q2 O+ [3 s0 v) q4 x1 a" g- p
; n. T9 e# y( d& m
  set-default-shape turtles "car"
, B% j1 e5 K8 w+ u6 ]5 W) {& S9 V5 [" Q" U" N; B
  if (num-cars > count roads)
: ?! ^* H2 q3 U3 f) V6 f  [
% d! g9 }  e. W. O: R5 K. Q! }    user-message (word "There are too many cars for the amount of "
5 J# \) |8 @. n! J$ h/ \" G6 B                       "road.  Either increase the amount of roads "- U! L8 Z7 W0 ?- {0 \
                       "by increasing the GRID-SIZE-X or "7 Z0 u% |' [8 P7 F, d2 |
                       "GRID-SIZE-Y sliders, or decrease the "& ~5 U5 Q. O% }) i* l( r
                       "number of cars by lowering the NUMBER slider.\n"2 v) U& E" `% y. A; g) N+ l" F
                       "The setup has stopped.")
. R) ~+ w( y% e% b! [7 |    stop
# I, l* U$ X+ W' D- @4 D  ]* g3 m4 _, e  l: v- ]
+ K+ d0 e* `7 S: b# a% Y2 f
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 Z' \; H& h( u" d3 N  |
  crt num-cars
7 X- ?' |8 o4 a( a4 w/ e  [
9 C# Y: ~3 E% ?* C( T6 H* a    setup-cars5 L. l8 y( ~, Y9 x
    set-car-color
! V" N* Y' P- V  K! K    record-data
- K& Z: i! r8 v7 b  ]
* A' Q- s& h% M$ L' F# E/ m& M9 p# K- ?# U
  ;; give the turtles an initial speed
& @0 D  O; l" S0 G  ask turtles [ set-car-speed ]2 o1 i9 e: _; D, h! y6 r

/ E7 J9 |, n0 O( ^: J, N8 ^7 k  reset-ticks
, k7 |  h3 S; m& Rend) o" y8 v* y, u! ?4 b6 `
! S% Z8 s2 r& C% q2 k2 a
;; Initialize the global variables to appropriate values7 @& _/ S, u+ m: ^3 K: v5 m" d
to setup-globals
! `+ e# z: [# l  set current-light nobody ;; just for now, since there are no lights yet
! t) b. D& V: ~8 x  set phase 0$ k8 c: r# ]2 r& A9 ]  g
  set num-cars-stopped 0
& K2 ^0 ~0 Q, r0 q7 S- ~' @  set grid-x-inc world-width / grid-size-x; B$ }0 ]5 g  \4 M# h% w3 e
  set grid-y-inc world-height / grid-size-y* {, ?- W2 l0 \8 }( I, v

" a+ {' Z5 d! ]9 W- _  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary. O: P( m1 B6 d  c" x
  set acceleration 0.099
/ ?$ r  \: ]2 u2 L# i  o3 Jend# V* Z1 L/ {* E1 ]( A" Y# q

! x. D% k# o0 T! B% z/ h: m;; Make the patches have appropriate colors, set up the roads and intersections agentsets,6 H9 t; o; ~1 x
;; and initialize the traffic lights to one setting" d, M% I3 h- }
to setup-patches
, e4 b" Z0 n4 c- N4 U2 L" _  ;; initialize the patch-owned variables and color the patches to a base-color
: h7 V: ~: D% z) }- s  ask patches0 S8 _# s' v8 |/ ?% l- b0 M
  [
" j, w, q5 w  b    set intersection? false" P7 U, X* T8 K' Q! l
    set auto? false3 A$ m2 X# l2 L- T/ F' F7 q4 _
    set green-light-up? true
1 k: V+ q  y4 j5 v$ r    set my-row -1* p3 G/ @# U; G: h. x. \; i
    set my-column -1
8 {  I* V1 e! v2 J* Q& M# ]' N( W    set my-phase -1
9 l' g& ~+ f: ~5 H, |$ o" X    set pcolor brown + 3& J. d4 l4 Q. z" w* I4 z2 j
  ], p) s$ H8 |) L; i! N( X2 F& q

1 d0 M( s+ z: i2 o3 t! J8 k4 \  ;; initialize the global variables that hold patch agentsets6 Y" J/ C2 Q8 G( N  m* b0 j
  set roads patches with, \! T# D2 K  `9 b% j) T' X
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ t' @  s. i% T7 `* \    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& ^0 m8 J4 v6 Z
  set intersections roads with: E( c5 m. x, @- {
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and: g5 K! M- @0 _& D
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! z8 t# g1 D  u+ ]5 E: P
! v. J7 V& z0 m, k( v
  ask roads [ set pcolor white ]( I3 j$ H- r' [6 s) Z  |1 ]* p
    setup-intersections
! X3 X; R- d* r/ F, p( G! b( u1 iend
, ~( H7 E! L# E/ t1 Q6 l其中定义道路的句子,如下所示,是什么意思啊?
' M/ m. x  T! i, F* R set roads patches with, h; F5 g" E8 d6 {8 n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
' l/ \3 C: I8 h! Q- H, e7 S( F* j4 R) @    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) g# u2 b  r5 ]1 m  ]1 `% w/ C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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