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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。2 [4 `0 Z& z# t+ ]' M
netlogo自带的social science--traffic grid这一例子当中,! @3 T1 C  w+ ^3 t. c' S: [% I
globals" K3 |1 \/ U/ T3 [* r, r1 V
[3 j1 R8 j' L+ y# D/ t
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
+ `, M* z9 z. h3 U" @/ j  grid-y-inc               ;; the amount of patches in between two roads in the y direction
  g0 T$ o4 E4 t6 ]/ i0 h  acceleration             ;; the constant that controls how much a car speeds up or slows down by if0 T% N# |6 l! t. ]) p6 ~! O/ J4 m
                           ;; it is to accelerate or decelerate
* s5 C1 _5 v+ p8 z9 J$ L4 A  phase                    ;; keeps track of the phase. P  O9 A) |6 |' _, p1 n6 @
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
7 T% g1 c6 _% y) g, Z' L! X! I5 b  current-light            ;; the currently selected light( B5 L5 N  J# d
- f+ I1 Q5 g  J" N/ y9 S
  ;; patch agentsets
1 C, h! \; T$ c6 {  intersections ;; agentset containing the patches that are intersections6 k) C) u3 o  q' e! I$ J
  roads         ;; agentset containing the patches that are roads0 e2 O( }! l+ X* j2 J
]
) C% A% ]+ l7 K9 @/ D5 A( n/ ]: M4 a- \& _: _" S; x  u
turtles-own8 t( z6 Q" M' S
[6 \* d9 {: {/ l  {# K) q7 R9 U
  speed     ;; the speed of the turtle0 f5 P. L3 Y$ l
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right/ j9 a4 C; k- j- O, _3 Y- U
  wait-time ;; the amount of time since the last time a turtle has moved
2 }3 D. ^0 h/ S9 X* ~]$ B; r  e* F# \& `8 E/ c

; n8 l0 N8 p( `- R4 o4 f: }2 _patches-own& P- ~+ z$ ?, S. M7 O6 F# f5 U
[) s' C) Z# D/ Q  c
  intersection?   ;; true if the patch is at the intersection of two roads
1 x0 j) q7 ^& @4 n" k3 [  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
2 x' O' Q1 V* b9 t                  ;; false for a non-intersection patches.+ r- r1 d4 H3 {$ Y/ N
  my-row          ;; the row of the intersection counting from the upper left corner of the4 b# F# g# {! [  i: f. z
                  ;; world.  -1 for non-intersection patches.
0 {: }' G$ E5 R# h  my-column       ;; the column of the intersection counting from the upper left corner of the( q  u# j0 t- Q& K
                  ;; world.  -1 for non-intersection patches.
1 t1 r, C' a9 m/ [% w9 w0 W1 R9 p  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.# H: L' @# W3 }' a
  auto?           ;; whether or not this intersection will switch automatically.
/ q$ H  d, t+ o" ]. S                  ;; false for non-intersection patches.
0 G9 N7 @. k0 h: q]' ]0 u  E+ h+ @' M
( ]6 Z! I, ^2 p: `) @4 P

& t0 V2 M$ ?9 u; K0 q& Q) |;;;;;;;;;;;;;;;;;;;;;;
( k, `0 ^3 e3 G' Q/ ^# }, ?+ N) W;; Setup Procedures ;;
  ^) d7 ]9 d3 B) s;;;;;;;;;;;;;;;;;;;;;;( v9 }4 W  v: [' l& Q4 ]: H; H+ P

, G% E; Y& j% h. k! N;; Initialize the display by giving the global and patch variables initial values.0 B2 ]9 w5 O  M9 A" V9 g! C6 U
;; Create num-cars of turtles if there are enough road patches for one turtle to; a7 e. `( f/ [7 {7 L9 }
;; be created per road patch. Set up the plots.
: M& L* f8 i0 K# a# t8 \7 L% D5 Nto setup
/ Z5 D1 B- b$ J; i5 N1 \  ca
9 V2 T' \& \; R& C: e# N  setup-globals: Q2 S) c) H5 v" D2 p9 m

8 x, C0 m1 ^6 I2 E# O5 c  ;; First we ask the patches to draw themselves and set up a few variables
# h. l2 ^( ^+ K! s- n8 |# O' ^; J  setup-patches5 h7 m" ~$ h- ?8 y6 o! Q$ U
  make-current one-of intersections, ~( z, A3 s0 [2 o5 z
  label-current
3 d( z$ p% q5 \4 B
( Q0 y+ @1 f/ D6 e  set-default-shape turtles "car") F" g% X+ M& \, t* M8 }: }
# T* |. p& [* H+ m( C
  if (num-cars > count roads)0 J" t/ f- @/ ^
  [
# M/ h7 Y5 T1 d9 N    user-message (word "There are too many cars for the amount of "
: h% S* v8 }$ [; P6 `                       "road.  Either increase the amount of roads "8 o+ o( \' h3 x! B5 B& b! c
                       "by increasing the GRID-SIZE-X or "2 _: J- M; F# ]5 ~" a
                       "GRID-SIZE-Y sliders, or decrease the "
  E8 p- b! ~' d0 U- O1 n" x( _6 t                       "number of cars by lowering the NUMBER slider.\n"
2 Q1 _6 y$ X8 |6 L3 Z% W                       "The setup has stopped.")+ G+ A( l( a- r8 \
    stop
0 D& R5 e9 D1 I0 l  ]
9 d" _/ J9 c: D; z
- S2 |+ y! n0 N5 E# ~6 }9 P% @  \  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
7 u5 j/ p8 b% F+ J  crt num-cars
! A% c- R5 p! e. h1 j  [8 i2 S$ s# }& o; c
    setup-cars7 W- Q9 Z* G5 V/ L0 a
    set-car-color
8 f8 C6 e/ }1 Q& v. h    record-data
" m: T" ?" L" V4 x3 A* w  ]( M! s9 ], r$ X2 g, P; ]4 f* w
) S. i7 c  ^4 m; c9 @
  ;; give the turtles an initial speed
6 V( R3 p2 k0 M  ask turtles [ set-car-speed ]
# _! F  Q9 F6 k% }" O" I, {& ]2 M3 P1 o
  reset-ticks
0 a7 f4 g# Q6 a! B$ Lend$ V: d6 g+ n0 ?3 c. `+ U: _
, v6 L$ j4 P4 y+ M, Y2 d8 |
;; Initialize the global variables to appropriate values
% \: E, V: k" q% ato setup-globals! s- G4 H* a& \) v3 D7 R% a
  set current-light nobody ;; just for now, since there are no lights yet
; i* J* r; G9 N0 p2 S9 }1 K& r' s  set phase 0- X  b" Q- `5 ^
  set num-cars-stopped 03 o/ n% |, @* n& C9 ?
  set grid-x-inc world-width / grid-size-x
) H2 g1 @0 g: {" ?# m& O  set grid-y-inc world-height / grid-size-y' ]: h! ^% R2 v& o, i" \$ U, D

2 {* a- k. F+ {: t  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
, B! S+ Q) u# s7 G, m  set acceleration 0.099
6 l. `& T5 C  H: [7 k% {end
( H# U* T) c# }/ {3 Q0 Z
9 H, n* [% v# u+ s( Q0 f;; Make the patches have appropriate colors, set up the roads and intersections agentsets,# @9 b* A4 M. o6 ?
;; and initialize the traffic lights to one setting9 U& X% ~1 }- v9 \8 T, y; F( P5 [3 ?
to setup-patches0 r3 i& s3 P4 s- c$ @. o& n
  ;; initialize the patch-owned variables and color the patches to a base-color
1 d8 b( t" c! ?: U$ q: o  ask patches
/ b& n& N/ A2 p1 B  [
' c+ T( ~9 W% O    set intersection? false
6 o& \+ j6 }0 W% V    set auto? false1 }" v( d; ^. R( _6 I. S1 u
    set green-light-up? true& }5 a7 }% x5 l# B' D( t
    set my-row -1
" W; N+ y% j+ @    set my-column -1
* g) m- V: \) Y! X7 i, y    set my-phase -1& y: Z+ b! L2 H
    set pcolor brown + 36 h/ N, R8 m+ ^; E
  ]) ]) m1 }8 T& q1 W( g8 y) g

+ o5 S0 _- |4 T( P4 i2 q  ;; initialize the global variables that hold patch agentsets
2 u% G2 e$ l7 J5 j0 N* l3 z# Q9 v! s  set roads patches with: s  N4 p  a' A5 n; N( J
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) s7 E1 Q) D' k1 Y% o5 r    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 a" E& A6 g& b- M" U6 P& }4 ^, U
  set intersections roads with
" J) U+ z: ^3 o+ g8 ^8 _    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and8 Y5 z7 K2 g, M% ^8 B
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 P  A1 }% @0 L$ z+ X. n/ x. `- b, G- T$ ]; z1 Q5 p
  ask roads [ set pcolor white ]
7 d2 \/ c4 w; T/ h5 A3 p    setup-intersections
. ]: B6 m8 k8 P: G% x  }  nend
; [  \. E6 P, p/ T3 h; E其中定义道路的句子,如下所示,是什么意思啊?1 r! g. E" ^9 V1 @0 V# e6 t
set roads patches with
6 J0 |' l  z3 b0 P1 `( ]    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or. J- q  l8 n8 h  c+ K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; N" G2 y* h( k( D/ M
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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