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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。
6 A( O" f; |- V8 B6 Snetlogo自带的social science--traffic grid这一例子当中,
& f! V! ~; R; d' I+ q( Jglobals
% s2 T% b( @" f1 |9 q[. g6 ~3 j; C% \* U
  grid-x-inc               ;; the amount of patches in between two roads in the x direction; G8 t* ~& f. ?# t
  grid-y-inc               ;; the amount of patches in between two roads in the y direction- n: K6 R1 U5 h/ O0 S3 q+ q" ^6 U( C
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if& F( t5 O" Y  n" o6 j
                           ;; it is to accelerate or decelerate
' A  C& K- N9 l3 Q8 m$ Y  phase                    ;; keeps track of the phase5 I9 Z* K! Y( o
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure% c; a* d" ?1 ]* r
  current-light            ;; the currently selected light
+ u% ?9 n- {1 U, ~/ f, d
( ]& c; U7 O3 N  ;; patch agentsets
0 d5 f1 x, _% Z$ Q% U! t2 z: ]  ?  intersections ;; agentset containing the patches that are intersections# u+ T3 e; M7 h4 v9 ^9 }
  roads         ;; agentset containing the patches that are roads
& l" H  y% |0 i. {  J1 I; }, q7 d]& u- T; m7 k8 ^& s- w

, p4 W: y3 M0 T7 C5 Hturtles-own
1 p- }- |* `) h( j[& _  ]0 N. y! t
  speed     ;; the speed of the turtle* K2 X$ w( D& Y% ]
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
0 A2 A! C9 x8 E: d* {$ }# k- B  wait-time ;; the amount of time since the last time a turtle has moved0 x& R! a6 l0 Q6 u
]
& Z  [9 T' C+ l" t! F) ]  L4 E! L  i' n: v
patches-own
. S3 V+ Q9 E$ K, m[
" P" U7 B0 D! t, E% L( r  intersection?   ;; true if the patch is at the intersection of two roads% [  R; G/ {: J7 @) }$ o
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
( z6 I* y! C; m, ]3 o                  ;; false for a non-intersection patches.
- U& p2 I& p9 E# G# f0 p* B  my-row          ;; the row of the intersection counting from the upper left corner of the8 v# U* X& K  d; }) \
                  ;; world.  -1 for non-intersection patches.% O2 j% c7 P1 V  O% u) r4 }! b
  my-column       ;; the column of the intersection counting from the upper left corner of the. X& U5 `1 Z  ]# R
                  ;; world.  -1 for non-intersection patches." m& S& F& J/ |1 Y- U* `' D( o" x
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.! E- J/ g1 f1 M9 K+ {) @
  auto?           ;; whether or not this intersection will switch automatically.
& Z. l/ ]' ?, t# K5 w( d                  ;; false for non-intersection patches.
: o) A9 F, w- T3 K5 w% _]
6 d: a7 [8 T( x$ k/ }( \' _7 h, x  d: j4 `( ^5 J0 J! [; h1 [
& ?& r4 }( @& D) H6 L/ }! _
;;;;;;;;;;;;;;;;;;;;;;2 ]9 n, s1 B" D% j
;; Setup Procedures ;;) b* {! k5 m' z0 ]$ k* g3 m: V
;;;;;;;;;;;;;;;;;;;;;;( F3 Y4 c" _5 |: B4 l% m# W% }& f& j
4 V  `5 Y7 A+ g' ?# ^
;; Initialize the display by giving the global and patch variables initial values.
( @, r0 M( a6 ~# r( `5 \3 v$ ^;; Create num-cars of turtles if there are enough road patches for one turtle to
7 w8 s9 j$ ~- t;; be created per road patch. Set up the plots." W2 O1 y! Q; }
to setup9 @  n% i* e) l, Q* p; O
  ca
6 H  n2 u$ e/ i' l* T+ F* r  setup-globals. h9 h% V# M  c' y1 _/ p% l% o, a

/ W/ i% [% j) ]& R  ;; First we ask the patches to draw themselves and set up a few variables
' E; x! S3 l+ R6 w  a- q* ?% u8 e1 B  setup-patches8 v" k- X1 G' T9 ^) @% J/ B
  make-current one-of intersections% [5 O5 u: U1 ~
  label-current
% K4 j" ?0 r! w
& j8 W% I# ^; @2 s1 D. [) ~0 `  set-default-shape turtles "car"/ N& l* m& i2 m) [
( K( o/ Y, Y" K3 d. A4 F
  if (num-cars > count roads)
/ @% t- T6 P2 `3 H2 _  [
( ?! P( z# H4 G3 C    user-message (word "There are too many cars for the amount of "
9 Z/ R. e  F; p8 H                       "road.  Either increase the amount of roads "
$ y  @# v3 C) z: u' ?; X                       "by increasing the GRID-SIZE-X or "
5 ^$ |9 P" N* h( {5 t                       "GRID-SIZE-Y sliders, or decrease the "$ Q! I: j, v9 k' Z* N9 m
                       "number of cars by lowering the NUMBER slider.\n"
5 R" T8 I7 [) I( d( P) F                       "The setup has stopped.")# v5 s9 G' f' `2 V* x3 {
    stop
0 o1 B; _5 g* R# Z  ]; d- D& w# \8 r5 {

9 w( |# Q) [! K/ ?  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
; |  O7 \4 f: R$ W: z/ p  crt num-cars
# Z7 h: w/ z% j0 F2 {6 `2 r  [
# X3 @4 {0 a% C& z    setup-cars% E7 U8 s2 g1 }3 v7 w0 l+ D
    set-car-color
+ P( ~$ v# ~. F% g7 c. W2 b4 G$ C    record-data
' m) t; m) T* K$ N. [  ]4 u$ a" ]# b# n# v3 T/ [

. q: l) b* ]" G: W7 l0 x; z  ;; give the turtles an initial speed
# c4 {  _8 D! x9 |) f4 s  ask turtles [ set-car-speed ]5 Y+ Z2 n8 x5 f4 M' C
$ ~" q6 x9 B$ h0 A) O( g5 _" ^
  reset-ticks
! L* E( K7 d, w) Pend
( J' V) T! {, h& C( ~/ ?- k* |
- K6 [2 T% E: j$ H' d5 K;; Initialize the global variables to appropriate values( n( q3 {' B& q) w. Z
to setup-globals' ~5 u0 U1 \1 C7 Z
  set current-light nobody ;; just for now, since there are no lights yet. q# `! h# |+ u# P) s3 E6 y
  set phase 0- M* x4 J8 x! V
  set num-cars-stopped 0
& Z' i" @6 m! ~& `9 Y$ X  set grid-x-inc world-width / grid-size-x
3 O) S- p9 N" d  set grid-y-inc world-height / grid-size-y" W- D3 H; W/ K/ l+ ]# }0 s. X

6 Y- V  I6 `" c0 B) y  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
0 V5 V1 W' P# t: Y; |  set acceleration 0.0998 W7 A2 x6 u7 D9 c! X" q1 k
end) O0 n/ x; H4 h2 O
$ P6 j8 ^) I8 d  F* S0 e
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,& T5 f+ b4 A0 \8 p
;; and initialize the traffic lights to one setting
$ J/ Z2 R; N1 h1 B. `3 s. c7 bto setup-patches0 i- ]. h7 t4 m3 c4 J& T1 I* u
  ;; initialize the patch-owned variables and color the patches to a base-color% c8 E$ Q7 a7 Y: J2 ^5 z
  ask patches
, R$ A+ z3 f; b. M; n- c7 [  [7 a$ O+ l# r' Z5 o0 L0 s' Z  n8 L% X
    set intersection? false% p- {; b  G7 y/ p& f4 y" k
    set auto? false
! d1 D2 f1 X& @8 _: v4 \  e% F    set green-light-up? true' T1 r/ n7 I$ m: I1 `, E* K( h
    set my-row -1
2 T, G/ n4 B; b+ P$ p$ G. z" `4 U    set my-column -19 \7 ~) y7 `* C% E
    set my-phase -1# |" v6 T# |! I2 M
    set pcolor brown + 3
3 K+ j  ^' m: a4 @: O  ]# [! {6 |8 n# f# A
- ]! M/ A. y0 L$ q8 E* R: U6 r
  ;; initialize the global variables that hold patch agentsets
" D" W8 S9 r6 L  set roads patches with- I" ?  u( ^, M
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% C' _1 V5 b, A% ?; f# I1 e
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# \' N1 j4 l2 w9 w
  set intersections roads with! z2 q, ?! k/ Q! K% Z( Q9 e
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
  W. J4 L9 G& X) e3 i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; D5 ^- ?1 s5 K. k
. {) ], S' v6 w+ O; S/ r$ a
  ask roads [ set pcolor white ]' `' G5 i1 d6 g' P# h
    setup-intersections9 T# U, G; H3 E4 R- j
end4 w8 N: M# J) W
其中定义道路的句子,如下所示,是什么意思啊?7 V- E  r# x+ a
set roads patches with
3 r6 P6 P- D* f/ M& L    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or# c- X1 Y1 N& V) e+ A% s1 r
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% Q. V5 T) _& |: Y" ^- A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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