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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。
; N" w: k2 H6 j% z% i- Bnetlogo自带的social science--traffic grid这一例子当中,
3 ~* L( \7 q% m1 b7 x! E* l3 Iglobals
1 d; G& E4 t, y- ^2 ?1 u[: x! Q1 P  V' E3 D, L7 q- Z
  grid-x-inc               ;; the amount of patches in between two roads in the x direction6 m. _& W5 I& B: O5 D
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
1 ~  p! e, i; \' k( `  acceleration             ;; the constant that controls how much a car speeds up or slows down by if, \$ @% x1 o. r. e! G
                           ;; it is to accelerate or decelerate
5 U- r/ m; h" L( l1 }, M$ Q  phase                    ;; keeps track of the phase( N( p$ Y6 V  c' u- c  s
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure6 @  k, X, F7 a6 \, J+ Z' L; g& ^6 z
  current-light            ;; the currently selected light% o8 V+ m0 l. \: q

4 y2 V6 [- z6 C9 a" M  ;; patch agentsets& Y+ v( [6 F* l# T! G
  intersections ;; agentset containing the patches that are intersections
$ N  I( \. }; n% a  roads         ;; agentset containing the patches that are roads# X+ u7 k9 g& ]1 Y  h
]
5 q" m" k0 k; h' X* [
1 [$ P7 A& i/ jturtles-own
7 _4 n7 v, ]+ O3 S; e: y[
, ~! t1 N, c9 s7 N( w  speed     ;; the speed of the turtle* ]; L2 F. t1 Z) }
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
2 Z5 Z7 E: }  m2 O' L  wait-time ;; the amount of time since the last time a turtle has moved
6 X0 o* Y8 d4 s  n# p. j]! b& u& D2 {" ~' `" h

! p* i& `: K& E' t5 F! h  I! |& |patches-own: C& @( H1 P7 R
[; E/ o' }+ Q5 T6 ^4 u
  intersection?   ;; true if the patch is at the intersection of two roads- f) n# H* x* d% F
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.* R: w. A5 z( Z# W
                  ;; false for a non-intersection patches.
% o  z* l+ c( S. K8 M! v  my-row          ;; the row of the intersection counting from the upper left corner of the
6 F" I2 J( e3 P) E& t0 N                  ;; world.  -1 for non-intersection patches.
& s! a9 ]7 U* P$ K3 ^  my-column       ;; the column of the intersection counting from the upper left corner of the
- @5 @8 B, l  P  r                  ;; world.  -1 for non-intersection patches.
7 H' T2 Y% B1 {( D) H: f+ L  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.4 d$ ?( {% H0 S/ p1 J
  auto?           ;; whether or not this intersection will switch automatically.+ G: s* @% s9 }' ?- W
                  ;; false for non-intersection patches." F. [% e! P# g% e8 N
]
3 n6 e# d- S( @( H+ L# ^0 h, `& s: a! G; m5 j4 G

! F3 z% k9 Z, i;;;;;;;;;;;;;;;;;;;;;;
# \, n5 v7 [7 A- A1 q$ f2 V, K;; Setup Procedures ;;
0 a1 F& a5 M5 A- G& o$ b;;;;;;;;;;;;;;;;;;;;;;
) E6 m: R/ q" l! [5 r, D+ a
$ b5 {, d/ L8 b;; Initialize the display by giving the global and patch variables initial values.
% S3 s% i4 i4 k  g2 r;; Create num-cars of turtles if there are enough road patches for one turtle to
: \0 a# ^: j6 u;; be created per road patch. Set up the plots.
& [3 |9 t2 r7 O1 \2 V! e* k, Pto setup1 Y* A/ B2 V/ n) M, \4 D9 a2 V: l
  ca
- A, Z- \2 j9 n, o4 Q6 f  setup-globals" o1 I. \* P' L
3 ?) e5 R# a8 W- x/ @! M
  ;; First we ask the patches to draw themselves and set up a few variables; H9 [( n% X2 y
  setup-patches
/ }0 V& A% Z" l4 \* W# x  make-current one-of intersections. H3 R; r" O3 M+ m3 J+ P2 v
  label-current
2 Z$ l" j& U4 ~" W! v3 y- Q( t+ Y2 c& E5 q6 A
  set-default-shape turtles "car"! a1 O& d. E5 r

$ o0 W& z: W3 B4 a4 b' v  if (num-cars > count roads)
& c) O* V$ J: [! J  [
( h: t. {% M: A1 H% Q& W    user-message (word "There are too many cars for the amount of "
# q- e1 ]' V6 O6 Z; n                       "road.  Either increase the amount of roads "% n1 L9 h  n" z3 T7 g
                       "by increasing the GRID-SIZE-X or "
% S9 s5 n5 X" F. t$ y  V                       "GRID-SIZE-Y sliders, or decrease the "0 g* ]6 h; k7 t0 D" Q
                       "number of cars by lowering the NUMBER slider.\n"
( g5 d  V( R  E; W- T                       "The setup has stopped.")$ X$ Y& z1 Z, @) S# p$ H
    stop
/ Q8 X8 o, Q! o6 S! N  ]: r5 g% [' Z0 e; j
. d" r- Y/ I2 h$ d$ n. H" l
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color0 U+ _' R% k4 ~# K& Y/ L4 s2 z
  crt num-cars4 \; y! E) j' u  r% k
  [; Q" C' t( U* F0 g
    setup-cars
, q3 P" `( D. F5 ^4 g$ |6 L    set-car-color# |/ J# k$ z) {0 v
    record-data
7 }, W) T" H% Y4 i2 {  ]
. _0 j& g! c, r/ N- H1 T0 W9 \  ]5 g* v* {7 i! U
  ;; give the turtles an initial speed1 K) {2 A5 k  N- T- V- m- y9 d- W- O( E
  ask turtles [ set-car-speed ]
) p5 u  M1 }5 S% a0 [& Z7 ~/ w
4 z+ V' x/ B4 l7 e. E  reset-ticks. E! v0 @, i8 l& A4 o! y
end
( k% y: j! \* d; w: o- k3 C
# w3 M2 X) [1 K! j;; Initialize the global variables to appropriate values! H1 Y+ B) o) d/ q" |  o
to setup-globals: y9 R. T9 E3 O9 q& \3 h
  set current-light nobody ;; just for now, since there are no lights yet
! Q% u. a" v5 D+ ]+ g( N9 ^  U  set phase 0
0 f  S, }" P' k! W. n  set num-cars-stopped 0
; q6 m+ A& M: I, u% @5 s4 F  set grid-x-inc world-width / grid-size-x
1 ~0 k* c0 F/ C' e0 ~  set grid-y-inc world-height / grid-size-y
9 ]' f* J) w  x' q+ g' L+ x& o( u( p' W3 {/ F- j% t' }# s
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary# C7 g0 q$ {4 T6 f: F
  set acceleration 0.099. U8 D) r+ B& A0 I. \
end8 k1 t  J' ~* Z

( u3 M: n/ d" }. }- C' [- {% z;; Make the patches have appropriate colors, set up the roads and intersections agentsets,8 I: G' Q, n8 |* A  G6 F# z: C5 _
;; and initialize the traffic lights to one setting
( z& l8 ^2 S8 M2 \) Tto setup-patches* j4 t: n9 S+ h% ?
  ;; initialize the patch-owned variables and color the patches to a base-color
- x8 y3 d7 i9 q+ ~4 K3 R8 W& [0 ]  ask patches7 D5 J* x9 g; }! E3 _) F
  [* W* b2 f$ B' \4 h
    set intersection? false8 |* Z5 I  E( [2 ]( i. }9 f
    set auto? false5 F- }  U3 [( \& P8 ^7 D
    set green-light-up? true
- ~1 e0 A, m7 Z( q1 n    set my-row -1
* T( j2 p( C' p8 ]0 }* H$ u2 n    set my-column -12 k: X3 t: \) B$ \! Q& \7 d$ n) E
    set my-phase -1( f: T6 {! m) _- I# e
    set pcolor brown + 3
1 I8 |6 {3 w( m  ]" h, g' a+ |1 N6 D% L+ }

& {* \0 ^3 @7 r3 n1 b  ;; initialize the global variables that hold patch agentsets1 I7 j' t5 C, t7 v! b* \1 J: F
  set roads patches with: E( W2 R$ c$ m7 X! a# U5 U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( z2 @/ L% R+ J7 h2 V3 ?" X, U    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! k) n5 k6 ?: e( n
  set intersections roads with5 L' B& c0 k8 u! i( B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and* {4 m/ i; A; A* q5 g2 r: h& s0 k
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 Z+ p$ h+ o) M+ r" |4 S4 k

$ J4 C% |3 M: V) u$ s, O  ask roads [ set pcolor white ]* R- F, z5 Y+ }& U4 U8 F
    setup-intersections4 t+ h0 u3 m9 w; m! }4 t+ |1 x* ]
end: X) [( j5 o9 B; y& F
其中定义道路的句子,如下所示,是什么意思啊?
& i: u* j) c  C! P( `3 r- O set roads patches with' }1 S8 G& p' U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: f: ?3 [7 U& H9 I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# I. D! [+ a+ y3 H& ^- 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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