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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。4 k" V8 {7 g4 r' X" c
netlogo自带的social science--traffic grid这一例子当中,0 k  \+ K) w3 t- `
globals  o5 @; K! \$ T$ b
[
8 m! V% D" y/ f. O1 f8 W( Y! G  grid-x-inc               ;; the amount of patches in between two roads in the x direction1 U) ~% ?/ Q% {' f
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
: }* ^  }& d3 k7 ?* n  acceleration             ;; the constant that controls how much a car speeds up or slows down by if4 {2 u" q. M1 x8 `2 L
                           ;; it is to accelerate or decelerate( Q. ^" t, L1 i; H8 r
  phase                    ;; keeps track of the phase. O$ ]; D$ x) y/ V1 _" B) L& ^  T8 l
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure" h# e# `0 v. {! Z
  current-light            ;; the currently selected light0 b: B: @9 x& }4 w

$ ^8 E3 ~. d: o7 B  ;; patch agentsets) S+ g0 c8 L& `; E- g. D# Z7 d
  intersections ;; agentset containing the patches that are intersections
# p& Q$ x: [$ m- U# w3 A  roads         ;; agentset containing the patches that are roads
' Z' m. }2 q. ?% }! r( p  v0 N]4 U( S7 u! q& P  l
" k0 Q! G$ x2 ]; M% d: v
turtles-own
2 q% r3 R0 @* h3 s& \[
" x$ A3 o# ?( N  K  speed     ;; the speed of the turtle6 D$ ?/ `2 y9 `! Z: i
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right' g' ]( k# M5 L, |7 h! O2 ~4 i) s8 k( r
  wait-time ;; the amount of time since the last time a turtle has moved
& w0 I/ `, q- \7 r0 S' R- {( c]
- J0 c: r" E8 f8 ]- v9 K2 W: M
! Q9 f) s- p7 @: b1 zpatches-own
9 M" K# N" {# L& w+ i) N[3 b9 y% _0 L4 E9 h( K: r
  intersection?   ;; true if the patch is at the intersection of two roads
+ i) o# b& y4 |  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
5 @. i3 s, g* p; C- g  B+ J                  ;; false for a non-intersection patches.. q9 q# _/ x. Z9 J, @2 v& s
  my-row          ;; the row of the intersection counting from the upper left corner of the' e; q& G5 }$ J
                  ;; world.  -1 for non-intersection patches.  s* N# S" f9 Z; h5 \* K' B9 J9 c
  my-column       ;; the column of the intersection counting from the upper left corner of the- d/ W5 C2 {6 L0 p! O
                  ;; world.  -1 for non-intersection patches.$ S' p# r! e2 `  y0 p( r) P$ F  b
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
( V( X, E& h4 m( O  auto?           ;; whether or not this intersection will switch automatically.
; W8 O' n9 u. `2 ]0 Q2 O                  ;; false for non-intersection patches.  H4 ^. G3 x( G' ~% O2 _7 Y4 J
]" s+ U2 {* n6 U$ y# A; a

) l; K4 m, R& q0 X- o' q4 Y6 Z
2 Y8 n8 R% G( ]6 w' A9 u. n0 y# p;;;;;;;;;;;;;;;;;;;;;;$ y3 q3 t7 S- `' f
;; Setup Procedures ;;* l( A) ?7 A  c" W% U" o
;;;;;;;;;;;;;;;;;;;;;;
8 P8 N+ O: l2 R* R8 [
& Y0 s. q! c; Y) i2 P1 Q: Z;; Initialize the display by giving the global and patch variables initial values.
( U& {+ J8 P: O0 f0 G" c8 b;; Create num-cars of turtles if there are enough road patches for one turtle to
) E. b7 S# j  ?  B+ U;; be created per road patch. Set up the plots.
9 Z" ]  c  m, I* l8 Yto setup
9 r) P) g2 K& ^( w/ K  r% \; F  ca" O6 K) R# N, h- {+ _' p
  setup-globals) j) j% _* E6 }' {* e$ y! a- ]

: M! d: Q2 g, [2 `4 p  ;; First we ask the patches to draw themselves and set up a few variables
5 U% P$ i; ?. L3 b7 T- l  setup-patches' {" V# ]" y* _2 p1 S' I
  make-current one-of intersections$ Y, r4 ^! Y2 P% ?
  label-current
. e# U$ d0 P5 d: ?! `9 i+ E& p; A9 l. f- ]0 `
  set-default-shape turtles "car"& c% b( i& u, _* f" W
9 [+ q/ A+ v  F( ^+ T) O- F
  if (num-cars > count roads)/ t" `8 }6 \- A% G/ u, D
  [) r7 ~; v0 h0 r4 C
    user-message (word "There are too many cars for the amount of "+ a+ o7 M) c: m) R
                       "road.  Either increase the amount of roads "0 B, b! o9 U( [  o* t5 s/ \8 v
                       "by increasing the GRID-SIZE-X or "
% e& F& \9 e, \  [8 l# u* Y7 Q                       "GRID-SIZE-Y sliders, or decrease the "
( }! h, g% A, G                       "number of cars by lowering the NUMBER slider.\n"
2 N5 U6 _* k4 _& P                       "The setup has stopped.")0 q" a5 x. H7 ~. B6 P5 `' ^
    stop9 w2 ^# A! m; B% S3 Z6 \% u
  ]
/ `6 {& l3 |- x  }- Y" z
; B5 K  N1 Z1 D4 S  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
0 J# a. R1 H" a! m' f- ^  V: |  [  crt num-cars
+ b4 v0 |# ~8 F' g7 M& y) w  [! f' l. l$ ]# M* A
    setup-cars9 G; z- q" V5 R4 H. M5 ^
    set-car-color
$ z. G* k3 q4 N5 e( d    record-data
! [+ P$ \, ?7 ~! |  ]
8 E' q( {  ~+ V: Y4 [5 [
5 w6 q* r  n. W1 {0 g; {" n  ;; give the turtles an initial speed( h; x" p6 B5 o. z. Z/ \: ~
  ask turtles [ set-car-speed ]
0 d& a* s+ l: Y* [6 n" f
2 w  m, u: U9 r/ |) |+ R  reset-ticks9 r4 S6 d$ n6 G* C* c* D6 I$ b
end3 @7 y/ T! S9 I3 X* z/ P6 z2 Q
. T) F' L* G8 e2 e
;; Initialize the global variables to appropriate values- {6 L; E6 A1 t
to setup-globals' g$ w* h# ?1 ?1 Q
  set current-light nobody ;; just for now, since there are no lights yet' |3 X5 X6 z  K- }) s# F5 i' ^* [
  set phase 0" e# \0 [+ u2 y* u
  set num-cars-stopped 00 w* r" x5 T/ p, g; }
  set grid-x-inc world-width / grid-size-x
9 a4 _- A2 j& g0 S1 Q' c0 N( z  set grid-y-inc world-height / grid-size-y
7 k- N  D: {( I9 U7 w6 k2 @0 A. K/ n2 A7 u
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, S' Y8 ]& u, R/ ^
  set acceleration 0.099- l! e& S$ ^4 S) P
end
: T3 N7 Z& L& U* P: O  q3 Z; Y3 L4 A0 c7 f
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
5 k8 S8 `) a7 o;; and initialize the traffic lights to one setting( Q9 L; j. L- F" y( O+ a
to setup-patches+ g0 l6 C% U. r1 Z6 _( C- X1 e
  ;; initialize the patch-owned variables and color the patches to a base-color5 e- A& s/ O3 v) _$ Q7 h/ L: B
  ask patches: K8 b) q9 R5 [& V+ [  J
  [
' q; J7 z2 X/ l: w; I4 V" P. W# W    set intersection? false, t+ n9 H2 `& }# W. g
    set auto? false
" b  d# q# o# A    set green-light-up? true% f' G1 ~+ Y( O) B
    set my-row -1
; A1 G0 ^( r- R  n: D/ Q' m. \; v    set my-column -1  H; }6 v/ s$ i) k9 w! }
    set my-phase -1
! b1 m) x9 I" }% g, J    set pcolor brown + 3
9 r8 w! Z# s' t0 m  ]
, R: l$ i( N5 Y
9 ]9 l! G) B* F. A% p% P. `' N( U4 p  ;; initialize the global variables that hold patch agentsets
3 O' F4 g2 R; ?$ ^  set roads patches with3 f+ ^7 j( B9 U6 P
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: H+ k3 F, o/ y5 T) K0 i' X
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# s, x- L4 h# B& S; C  set intersections roads with
8 G1 x, y' l: B' |7 Y: P+ }    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
1 l1 }  q5 k. i7 g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% x/ G5 k5 ]' K
" W7 ~3 h! d4 a* @$ ]) d  ask roads [ set pcolor white ]+ m2 [/ @1 O' D9 R, c
    setup-intersections3 Q8 Z6 u" \; f) g5 }' q/ ]2 Q2 O
end
. I' |9 J  i$ c5 G其中定义道路的句子,如下所示,是什么意思啊?
8 T& F6 D' ?/ R& A+ | set roads patches with
* O% z" |8 x% l" Y7 F    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ ]& n, K: X) [. ]' H/ Q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ ~- z4 G9 i3 l3 p3 Z% q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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