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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。
* R& m" F$ e* N2 h( vnetlogo自带的social science--traffic grid这一例子当中,( r; p, f# Q+ f+ S! s8 u$ s
globals
5 a0 j8 c# s: k% U9 T- i0 w[
- y0 U) z$ k- R. C% b, h0 x3 H% G  grid-x-inc               ;; the amount of patches in between two roads in the x direction
3 O( `  N8 ?. L/ Y# j' i  grid-y-inc               ;; the amount of patches in between two roads in the y direction1 ]' r: a" ~% p' G7 _
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
' j4 g- `8 d: r# y* b/ l2 b. o$ G                           ;; it is to accelerate or decelerate6 ^% O4 t- b" T
  phase                    ;; keeps track of the phase
+ r9 H; z  N# |7 N5 }5 v7 S/ n  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure0 F. m& A0 s8 q1 b; Q) R
  current-light            ;; the currently selected light
. O1 {4 K( _+ x! w& @: @4 E$ N
+ i8 _7 e" }- N- i! o7 {, B) h  ;; patch agentsets
* {- b3 P0 r, X+ c4 Y- W; q  intersections ;; agentset containing the patches that are intersections
8 m& [4 F2 f* h) ]: R, B4 n  roads         ;; agentset containing the patches that are roads: `+ D% y# q4 i# w( ~# |, o3 }# D
]: U, r1 J) \" v! f+ F

9 n  _+ r- g8 e+ r, b( Uturtles-own
8 D9 X0 g4 v$ j6 Q! B2 e[8 O9 s- e" p7 H% ]
  speed     ;; the speed of the turtle6 ^# \; v. z% k7 W2 R6 f" Z' ]
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
7 d* e! e8 b( E8 |/ [  wait-time ;; the amount of time since the last time a turtle has moved' J  L  [/ g( Y* C! Z) A; U1 x- i
]
" v; _5 X- W) b' p4 F2 E6 `" A; f  g; M
patches-own
$ h3 h! E- z7 z/ D[
% S5 L! \$ A' e2 Q( z- c/ b) w/ c  intersection?   ;; true if the patch is at the intersection of two roads; {; i3 P8 s# O" I7 K, t0 R7 }7 Y0 Q+ }. A
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.' o$ C5 N: |0 K# ^
                  ;; false for a non-intersection patches.2 H7 }! U, V' G( h
  my-row          ;; the row of the intersection counting from the upper left corner of the5 N' m2 Z' ]6 A( r- O/ N
                  ;; world.  -1 for non-intersection patches.  @2 q( c/ |/ n) S  i
  my-column       ;; the column of the intersection counting from the upper left corner of the! |# H7 M& N, T7 x
                  ;; world.  -1 for non-intersection patches.6 A: E6 z2 O' S$ X
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.- _2 h, Y! _0 L
  auto?           ;; whether or not this intersection will switch automatically.
8 t( t, X' B% e                  ;; false for non-intersection patches.$ @( u! U6 E0 `; u9 t
]) g6 h  x8 f! c4 Y1 M. E

; p* B' e# E3 l$ m% r/ c2 T8 b) e4 x4 e! J6 r+ |
;;;;;;;;;;;;;;;;;;;;;;* h5 M& S" `: l, C" e
;; Setup Procedures ;;
+ {4 c* Z7 ], Q" M" [/ I;;;;;;;;;;;;;;;;;;;;;;0 k  a. u/ ]6 N( Q7 V. r

9 v, O7 R% i; M. r' F: o  L;; Initialize the display by giving the global and patch variables initial values.$ [- \: D( S" J' v
;; Create num-cars of turtles if there are enough road patches for one turtle to
8 L& E0 c8 ~% K# S;; be created per road patch. Set up the plots.
; z( q* {) _8 w1 Zto setup* W2 A2 B5 ?& s! J) x- v
  ca, r: O8 v1 s. \( {  t5 m$ A
  setup-globals$ K, W& g  c1 v: z/ \
0 p' b+ d( n% X% c2 A/ \( r
  ;; First we ask the patches to draw themselves and set up a few variables! R( e( R" C6 K5 u9 l
  setup-patches; S: K, \7 Y, H) _5 A
  make-current one-of intersections
" t* v! N, W3 `# R4 f* ]8 K  label-current
+ G  Z) h! x6 M5 ?8 b; X) n$ D1 @$ B
  set-default-shape turtles "car"
! Y8 I2 f/ o+ w7 x+ \( T
* g2 Z$ H! d  o* r) W) ]  if (num-cars > count roads)9 \, {0 \! a$ v2 [9 d
  [
! k* ~' C; v1 o/ J1 c, Z. m/ p- l  J- H    user-message (word "There are too many cars for the amount of "
+ S+ t' t0 z' P4 k7 ]                       "road.  Either increase the amount of roads "
# P# Q, n7 F/ O# C& B' x7 g/ D                       "by increasing the GRID-SIZE-X or "
6 k, y( C) J" W0 ^/ E                       "GRID-SIZE-Y sliders, or decrease the "
# q  S" z5 S- p+ B6 a% H                       "number of cars by lowering the NUMBER slider.\n"7 T- p  O  j3 x
                       "The setup has stopped."). I, N: S" P. ?1 R
    stop( D* g& ?- K5 N1 C) [; F
  ]1 i' H( t4 y+ M6 H* c) C3 E4 n% |

/ s6 z  w& N- G( B  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
+ L# U. q% z8 k0 Z/ {5 v  crt num-cars6 a0 u0 Q( ]: O
  [2 _8 y$ o! T2 R- _0 O6 r# z/ Z% o
    setup-cars
# v& H# ]( L+ P/ [4 m5 u7 Y    set-car-color
& T3 u( T/ g& ?  P    record-data. a% Q; h; p  z8 C& c
  ]
& {; G$ k* S, X  ?& L! }
' K& _, I0 ~& w/ L( N1 J- J- d  ;; give the turtles an initial speed
, J1 x1 G+ }9 K& u, b; i9 C: i  ask turtles [ set-car-speed ]2 e6 P1 H+ l0 b: s3 k

" g3 ^% `# a9 z5 h8 K0 M) k1 P  reset-ticks: a8 K) B' v/ s1 I2 k8 u
end
, R8 D, `! _4 F/ e/ q% D4 C2 v" d6 r" s
;; Initialize the global variables to appropriate values
, h. U! k' C* p8 Z. h1 Y+ ~to setup-globals2 Y7 U% }" f; j( L3 R7 U/ Y1 O
  set current-light nobody ;; just for now, since there are no lights yet
$ d8 `+ X+ ?( C/ T8 i! S  set phase 0
4 i/ s' X2 h: X! R  set num-cars-stopped 0- V7 _. }' y5 K
  set grid-x-inc world-width / grid-size-x
; f* }: x$ p2 R8 ^  set grid-y-inc world-height / grid-size-y
, \' D. }( ~0 {
5 Z% ]& w$ p/ H- z  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
$ C7 N5 ~9 L  _  set acceleration 0.099' ?/ n6 c0 ]: u7 |# O. i$ A
end
8 Q8 {% Q: R5 ~7 i6 Y6 X6 k( e1 v
; a3 j3 n! p( Z& B, I& };; Make the patches have appropriate colors, set up the roads and intersections agentsets,
0 ?! x& {7 c9 @; l& }2 v" m;; and initialize the traffic lights to one setting
6 f" N: s' y; P; j0 ]* ~# [to setup-patches
! q$ k4 s$ G, c0 U  a4 U; F5 E  ;; initialize the patch-owned variables and color the patches to a base-color: \+ B% o3 n& q, j5 P  J. r
  ask patches2 P1 ~5 e) V$ S7 q
  [1 e  T. R( y* s7 E+ D
    set intersection? false0 r1 @4 }" `0 ^- ]) s  y
    set auto? false: ?. a; q+ [  z8 R
    set green-light-up? true/ |3 x8 h) L1 _% U/ |
    set my-row -1
/ L" P/ I- U; ~) {5 n    set my-column -1# ?- g9 W. b) i! Q8 Y
    set my-phase -1# c7 ^2 W9 c# ]& L8 B! N
    set pcolor brown + 3# V9 _' N3 r* ]% N  i
  ]7 i$ j0 k2 ~' o+ B9 F1 C* R) N4 C
# H; Y4 M: }8 _# W# l- w  |* i
  ;; initialize the global variables that hold patch agentsets
6 y. y' O+ s0 F  set roads patches with
  `/ ?6 \1 \: P+ v# J4 x    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" l/ B" z$ a2 a# u# Q6 M/ T8 y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% U* F1 [* L( S3 i7 [
  set intersections roads with
' z: a& o$ I' I6 M$ [% k+ i" v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and' t, ~. }, J5 O/ r0 y; @% O
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 N: ^8 F2 L3 R& y5 i
% N) B1 \5 h4 S1 c+ y- c1 _  ask roads [ set pcolor white ]' u& }8 C7 H: D. q# {7 q+ m
    setup-intersections% c+ U3 b4 s' o
end
" c- w, g) c- g其中定义道路的句子,如下所示,是什么意思啊?, K# N8 o7 g) x/ l
set roads patches with
2 H) |6 `' \; t/ a3 p5 C    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* F8 T" X# G! g2 J5 ~% m
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 J4 K* s1 s* w0 M8 d2 j/ s6 p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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