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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。9 o& I, a# \4 a6 h; Q
netlogo自带的social science--traffic grid这一例子当中,
$ N' |! I7 c7 W* P/ \6 N2 Z& D5 aglobals$ P( o2 G8 B  L* \6 N
[. b) [- B# t5 d
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
9 N% k7 _" u8 r1 ~- p. e  X  grid-y-inc               ;; the amount of patches in between two roads in the y direction
! x- S$ s8 j, M3 H, c7 t( f  acceleration             ;; the constant that controls how much a car speeds up or slows down by if$ u: T0 @% g( {# t, T. p
                           ;; it is to accelerate or decelerate
& _" z4 x" w4 x! H# n% z! ?  phase                    ;; keeps track of the phase) r! ?1 E0 @4 d9 D
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
( v  [" k; f, f: u. \  current-light            ;; the currently selected light) r, e" t2 p9 s# c+ n5 j9 \
. N/ K/ @' {* \# I: i1 a
  ;; patch agentsets5 t0 u) F5 U/ r9 p4 Z$ a& l8 @
  intersections ;; agentset containing the patches that are intersections
" U' y+ A- j. z& _; c+ x( ]( l  roads         ;; agentset containing the patches that are roads
3 k* `. E) Y9 ~5 j7 P]
. j* ?& a" ?( ]  {; V& G1 v1 L+ x1 H& U6 o3 ?* j$ u
turtles-own1 x5 s8 k% o& s8 h' L9 d7 I
[7 {  f# T3 [( j# t% a
  speed     ;; the speed of the turtle
- _! ]' f6 ]4 g' G  up-car?   ;; true if the turtle moves downwards and false if it moves to the right* F. `* S' c) q8 o& A+ F! {
  wait-time ;; the amount of time since the last time a turtle has moved
1 C% K/ [5 D; Z( `) l]
7 x$ k- u- `7 [$ N/ N+ ?) N) R# A' I
patches-own
3 i* S, R; u4 N/ c9 H/ Z5 g" f% L[
2 C6 }/ r4 y4 D- y, A  intersection?   ;; true if the patch is at the intersection of two roads
2 F, T3 ?# Z7 [$ Y  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.# \! n2 M$ u$ `7 Z# J5 j8 G
                  ;; false for a non-intersection patches.
+ w! c$ X, q- y1 g9 [" A5 |  my-row          ;; the row of the intersection counting from the upper left corner of the
/ f9 S  }4 b8 M8 f! X4 M7 m                  ;; world.  -1 for non-intersection patches.! \! L) u- v. T4 D- \$ k" |  Y
  my-column       ;; the column of the intersection counting from the upper left corner of the
: t. Z: r$ W# a. F/ w1 J4 g                  ;; world.  -1 for non-intersection patches.
" }1 z) m% h9 l8 r9 ~) l, }  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.6 R% ?0 l7 K+ f# L* y8 V
  auto?           ;; whether or not this intersection will switch automatically.
* y9 u  }& h6 O" v                  ;; false for non-intersection patches., m5 h: s- l: N" _$ _3 X
]
8 w3 o5 T) D3 B* E. ~
9 Y  x' v, ]; l' F
- [0 E! n5 l9 z" l) i1 D: O3 L;;;;;;;;;;;;;;;;;;;;;;& D* ~5 T' v. S3 W3 Y
;; Setup Procedures ;;
  i1 k+ b# ]6 ]/ E9 G. L1 u;;;;;;;;;;;;;;;;;;;;;;& t; N# ^& Z6 B+ N; D2 T: S

+ `0 W5 E9 p* p8 S;; Initialize the display by giving the global and patch variables initial values.
2 c+ R. A9 l5 |+ z; O. A! U* h3 S;; Create num-cars of turtles if there are enough road patches for one turtle to4 B% Q. R# P* A! c3 Q, d
;; be created per road patch. Set up the plots.
: w: U$ S" |) X' m2 F4 _to setup
3 D* r& K' u$ w  b: U5 a# @; L  ca
" m$ I  ^6 Y. o6 D. ?% R  setup-globals
0 |) T0 j  F* P' u' \
& \7 a" F+ ]" K1 A# x  ;; First we ask the patches to draw themselves and set up a few variables3 H- z- W; v( ]
  setup-patches
! c& g# b. P% m1 Z' ]- N' l  make-current one-of intersections
1 }2 B. c& |  `% [  label-current
- e4 O0 C, D% C2 ?3 a$ T6 w
% H6 m7 K/ S- ~  G  set-default-shape turtles "car"8 R9 ~" h0 B" _' o, ^9 H) ?
) w. ^) A& b5 l( G: t
  if (num-cars > count roads)
: B8 c8 y; d1 H7 n7 u  A0 w  [4 I3 P4 c" D3 d7 O% R
    user-message (word "There are too many cars for the amount of "& ^- N% S. Y4 [# }0 s
                       "road.  Either increase the amount of roads "
' u6 H- P3 F- E" t" r                       "by increasing the GRID-SIZE-X or "
- V$ z! ]2 B5 r7 E9 X3 u                       "GRID-SIZE-Y sliders, or decrease the ": L5 j: E( M; K! @
                       "number of cars by lowering the NUMBER slider.\n", D8 C- ?1 s& U8 R6 A) l
                       "The setup has stopped.")0 T! _* N8 ]' M3 ~: h" j
    stop
+ ~( s( U& q: x0 L2 |1 X  ]
' T4 |# [4 X8 _3 {0 j+ \5 ]5 T
! q7 D' T) r. h( ]& c% m  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
  R( I0 b5 I, z: K0 n  crt num-cars2 s/ f0 t" |. U3 O7 C
  [
: [- U' P; p' t! J0 t- r9 I% Z( ]/ z9 ~( J    setup-cars' E& `/ b/ M" V( h) {! K' t+ i% k5 W
    set-car-color
1 j, O7 D0 n7 u7 k. C* ?    record-data% N2 g) J+ j( o8 U
  ]4 ^0 |! v6 S) I3 z! w8 S6 r% c
) O& k! h3 O1 n% C0 J0 B( T
  ;; give the turtles an initial speed9 N, H) A3 u. |* K+ m
  ask turtles [ set-car-speed ]
9 E1 W. ?: n4 m5 Y& W! ]3 h" @( v: A
  reset-ticks
3 b/ Z8 K& a: K% L. Mend1 V6 A; K; G' ~( W) a
6 Z3 E; i$ H" r$ ^$ R1 q
;; Initialize the global variables to appropriate values
$ m2 v, A' @* [0 |9 Hto setup-globals
/ z/ r( |3 v! _" U) ~7 \) s" G  set current-light nobody ;; just for now, since there are no lights yet  W7 M' ^1 A9 N  T2 z5 m5 G9 N
  set phase 0
3 c/ k& j) M" _7 Q0 H' z+ H: T  set num-cars-stopped 0
' E2 a  @! ]0 i  q7 g+ b# U4 E7 c  set grid-x-inc world-width / grid-size-x
& s' O: k: o" v- Y: G( \  set grid-y-inc world-height / grid-size-y
7 [2 H  ~( L9 @# a/ W* ~0 k1 E, d  g" ]$ Z* d# m, d) H
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
3 u$ y/ v8 K9 `6 O  set acceleration 0.099
7 D6 |+ ?6 Z% c; I' u$ c% J8 Send
& |) \6 p- }/ Z: z
! \4 \2 J, }% i; D1 h" k: w;; Make the patches have appropriate colors, set up the roads and intersections agentsets,* f5 A" V, t/ |( [7 n% m
;; and initialize the traffic lights to one setting; K  P1 J- I  i
to setup-patches5 u: X" r5 r* v+ P1 A) P$ m
  ;; initialize the patch-owned variables and color the patches to a base-color
3 Q) m' I) D6 j* _8 I! z  ask patches
; b- l, O" C2 B) c( P  K0 {! j" o  [9 A9 Y+ n6 ?4 k
    set intersection? false
* Q! d- L8 L) j    set auto? false* \% n6 u1 a4 I$ s: G. g& p) O/ S
    set green-light-up? true
& j+ G: e1 L4 {( c6 ^# d    set my-row -1
  l) H/ W2 M& K% I3 s$ f: `# L    set my-column -1
+ q/ _  W+ U- G. l5 y    set my-phase -1" _/ ]# N- O% i6 ^
    set pcolor brown + 3
5 ^! u6 c! @3 O# H- t0 i  ]
( y( {. c9 k% m
8 p* C# v; p4 ?1 K$ c- c3 y  ;; initialize the global variables that hold patch agentsets$ a9 ?7 U( V6 t  n9 y- }- E& d# w3 j
  set roads patches with0 x/ \. x0 _5 p
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, U/ o3 C$ c3 c" `- i$ J2 U5 v' ^4 M2 F
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* v* O7 e  d$ }8 M
  set intersections roads with
: h6 h/ x( r( k2 o! E" M    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and+ D$ m2 k- D5 K- T  k) W, ]) h9 G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! W0 s3 [1 }9 x( J& X
5 o9 A/ ~) w) B' O$ a- n. x  P+ x
  ask roads [ set pcolor white ]
' D4 S: s# n+ e: Q* R( d/ J  d    setup-intersections) f+ i3 I: M1 n: P
end3 G7 ]: p* a  y6 N" S
其中定义道路的句子,如下所示,是什么意思啊?
/ k$ g1 N, b" \0 V set roads patches with
% ]. K" }2 l  E$ B; _( p    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 u( M3 Y  ~% u    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' i4 f+ N& E9 T& m! ]  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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