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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。/ m! B( t# S" T: ~
netlogo自带的social science--traffic grid这一例子当中,
" S! U" R$ {; U. T/ r, D' nglobals
- k5 X4 y  `+ P5 J- a/ t[7 j+ h: d7 I. Y# }: q
  grid-x-inc               ;; the amount of patches in between two roads in the x direction, B" e& T" I) X4 F, N* ?, `
  grid-y-inc               ;; the amount of patches in between two roads in the y direction3 F& }/ _$ Z1 N6 F  S
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if& Y6 a( m) K+ ]; P
                           ;; it is to accelerate or decelerate* z: [7 C9 {- F! o+ K3 A
  phase                    ;; keeps track of the phase- u% _# w2 ?8 x. p7 _
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure; w9 s' H' V; }* V. [4 K
  current-light            ;; the currently selected light" o# K% ^$ X  M9 e

! }' v. E6 g- N: q) G5 e* T  F; D  ;; patch agentsets
- J3 T( I: C+ ^+ }; r  intersections ;; agentset containing the patches that are intersections# D0 s8 w' a# `$ t; z/ t2 [
  roads         ;; agentset containing the patches that are roads
/ ]/ r) I/ |/ q# u8 ]8 S]( n7 N* `, R& T0 n9 G" c7 L; u( x  {
8 ~1 d- c( ^1 Q) `: B- ?  }4 m
turtles-own( }9 b! i. `5 X6 T' w
[
1 m- L, Y  a7 [% L% h5 h& Z8 |  speed     ;; the speed of the turtle
& b! p# e- U3 K/ m, l, B/ ^( Y& p  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
: A+ ^% s5 y6 T$ Y/ a8 w2 `: x  wait-time ;; the amount of time since the last time a turtle has moved
' k7 Z5 o( i* j9 A% E]
" |) x2 A+ N" W9 K% l& d
& G  |: u* N- d) \2 S, O/ |patches-own
4 o. B+ p. o! q[8 W( R) ~" a* X, v# p. D7 `% ^
  intersection?   ;; true if the patch is at the intersection of two roads
1 p" H4 b  P- Y4 W( D. ^9 R4 w  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
8 z2 I: K$ O0 P9 H1 n% m4 V                  ;; false for a non-intersection patches.
, L4 U( }4 {. X) f, a7 M5 }  my-row          ;; the row of the intersection counting from the upper left corner of the/ o! P9 B" F: C3 ]$ D
                  ;; world.  -1 for non-intersection patches.  W+ R1 P% S4 [; |- Q; N& j  h
  my-column       ;; the column of the intersection counting from the upper left corner of the
5 ?& n" l3 q) p3 u6 L                  ;; world.  -1 for non-intersection patches.9 v5 D* {( O  D0 h  ]
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.# j, W0 {0 K! ?+ [8 p
  auto?           ;; whether or not this intersection will switch automatically.
; i" l2 [9 b/ J. M                  ;; false for non-intersection patches.$ D+ Q) U/ a7 b0 j
]$ k3 [' |4 z6 {! e5 B

, F( x* b4 D6 Q3 n( M, O
' C4 |+ l) L6 w* j: };;;;;;;;;;;;;;;;;;;;;;* C4 z) R7 c" z, X$ m6 Z
;; Setup Procedures ;;
0 r. E* }- R- E9 C2 ?;;;;;;;;;;;;;;;;;;;;;;
  `+ i7 I5 R" T& r0 U. Q5 H6 L
0 }* U* A; o8 v;; Initialize the display by giving the global and patch variables initial values.
3 ^% `# N3 C( H% P;; Create num-cars of turtles if there are enough road patches for one turtle to1 d! _4 a; y! t2 X
;; be created per road patch. Set up the plots., K1 v! w' q9 ]2 v
to setup6 l5 ]1 Q, D( g9 ~' l4 [1 p9 w2 a
  ca, w* E) W# \7 m4 X# Y: [
  setup-globals
$ M# s3 h) ?+ Z
+ t6 U" I5 w; C& C2 x3 s. K  ;; First we ask the patches to draw themselves and set up a few variables+ i; V2 V- q' @& \
  setup-patches
, k) K; I. I" L4 a% j& T- h  make-current one-of intersections
1 s$ t; e7 F* b% L" P  label-current
* {/ W$ H2 ?7 h( y! `: G) i* w. w; h& Q4 h$ E6 q
  set-default-shape turtles "car"9 k! d/ k: g& J* E: a2 K

' d. d1 `+ M; A3 g) L  if (num-cars > count roads)5 m$ }( V4 f+ _8 K
  [- U# _; l8 b' R) J
    user-message (word "There are too many cars for the amount of ": }. G" ^3 o  f1 J' J4 b1 _+ ?
                       "road.  Either increase the amount of roads "+ l* T) A" u3 m* x2 k7 k
                       "by increasing the GRID-SIZE-X or "" k7 O* U9 \, Z( r5 i' Y
                       "GRID-SIZE-Y sliders, or decrease the "
" G/ E, O& f2 u$ B( J) J                       "number of cars by lowering the NUMBER slider.\n"
* t% [( C, ?- i/ `1 x! G5 a( r                       "The setup has stopped.")
- f; k2 K4 T7 \$ ^" W    stop
  D. W5 b: q& x- l  ]) n8 X7 h/ ^1 D8 J) q. p
1 D  z/ i! e( @& v- t$ n( n  L2 [
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
8 j& ?" V7 c' Q  crt num-cars8 ~1 P8 m! ^' k3 p% n
  [5 i1 M! I9 N/ U1 s: @
    setup-cars
# C& v/ l9 v& g" r5 ~4 p6 l. p    set-car-color; t& f; o5 z9 X4 ^) |4 M
    record-data/ l0 e8 ]8 f' X" q% U. U; `
  ]
- M# V9 P: p9 v
8 J* w2 b" R6 B0 h/ G( W  ;; give the turtles an initial speed
; V: P- F, n6 }  ask turtles [ set-car-speed ]. X/ X: [3 x. |

5 `. P1 z2 b% _/ }' E  reset-ticks
1 H7 y; ~9 e8 Jend) ?( {8 y+ C& B) Y, h" f
: T# |# b, x; n% D, r; Z" I
;; Initialize the global variables to appropriate values, U5 G! P- M- i( m
to setup-globals- ^1 T7 }" d) O7 j
  set current-light nobody ;; just for now, since there are no lights yet" \! j8 }0 J  u% g+ ~! Y
  set phase 0' ]* z! c6 o( j
  set num-cars-stopped 0
  i# g& q* i. \9 I* {6 G* P  set grid-x-inc world-width / grid-size-x
# `6 N; w! Y# m* R$ L$ f# t  set grid-y-inc world-height / grid-size-y! K# D5 d, J, J9 y7 V. `! r6 Z/ u3 c

" T7 |1 Q6 P- X' Z" Q' N  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary: @- k( U1 U' V  p- f: b9 _5 |1 O
  set acceleration 0.099. O' }! o3 M3 A/ W; Y! M' w
end
! D6 E% m7 {- M+ L: u* d+ D3 B. X! v: D& U, Q9 D
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
: g) p* _$ D: W7 k" M' ];; and initialize the traffic lights to one setting
7 x' c7 ^8 a& `+ I- g  B8 ^4 G4 Rto setup-patches1 I) M& ^$ r, i0 e5 ]( m( |
  ;; initialize the patch-owned variables and color the patches to a base-color8 U( h3 w: _5 U/ j
  ask patches
. i# s7 j7 |& w) G2 ~( @  [# I0 N' ?! F+ _) j
    set intersection? false
, _- {8 G% K. t6 T" K& b* R    set auto? false7 a7 c: b* T1 q+ Z
    set green-light-up? true# u$ T9 Q+ l' l3 V. z6 q& r
    set my-row -1. g/ i  a3 Q' M
    set my-column -1) r, W& @0 M; W' \, I5 D
    set my-phase -1
! c1 m9 Y) T9 q1 u. @    set pcolor brown + 3% [& G. X- W" L9 Q' Z5 T
  ]) i8 E- Y7 y4 H3 o/ T  W
( I8 }- n. K* i/ j& _
  ;; initialize the global variables that hold patch agentsets, L6 P7 s" s) w9 N$ t, x
  set roads patches with
& L3 Z3 o1 U# g$ L1 D; y! h4 _5 p1 _    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 M, w7 n& B- D1 n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 j7 f; d% i4 Y5 `4 n6 i  set intersections roads with
7 b: x& T+ U1 @# a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
4 K. w/ D( `" r3 w3 k  h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! j( ^9 y) `1 Q) X' g) @' B3 ]! c9 N

! d" _, z- s! ~7 ^# Q/ S  ask roads [ set pcolor white ]
1 \8 _# U; P3 I; {- m. r" I. z    setup-intersections# K8 {# S- ?: \( r; K! V
end# r7 V! D; ^7 c2 u, B
其中定义道路的句子,如下所示,是什么意思啊?
" T8 s4 a; o8 T' L; r8 `& } set roads patches with. G; k5 o* [) t" f6 s7 W: w/ K
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& p1 w# H, b8 p6 F* Q2 p
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- R* R3 ]7 B; U( G/ M& F  b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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