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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: H. l# g- |4 H" enetlogo自带的social science--traffic grid这一例子当中,9 C- G$ u2 ^! P( [
globals
8 v1 Z6 C8 a  D! ~1 x) ~[
6 N! {4 X8 I$ y* _/ P; K  grid-x-inc               ;; the amount of patches in between two roads in the x direction
1 d. S9 S8 S; p9 i  grid-y-inc               ;; the amount of patches in between two roads in the y direction: M7 t0 W  X1 ^4 A4 H7 ^! H) @
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
: w. J3 ~9 W+ `' G; m4 i7 R                           ;; it is to accelerate or decelerate9 V  ?6 a% _  D
  phase                    ;; keeps track of the phase1 u& e! Y. T  @
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
) i3 r0 H! v: H$ a' _: O2 z, q  current-light            ;; the currently selected light( \+ u5 n: d1 q# Y. B" G! w
# H# E! G. {5 x' @0 I
  ;; patch agentsets% L7 @% ~+ R8 ^' Z+ \6 u. Y
  intersections ;; agentset containing the patches that are intersections
* @, J' }: ?, M  roads         ;; agentset containing the patches that are roads  N$ F1 o+ S% }. y, y+ ~0 ?! m7 n
]6 t* V7 @+ J1 D5 v, L5 j: y2 g

9 j3 L, A' L! Q) _$ F8 c4 fturtles-own
2 o+ W4 O" I: w& V! @$ G[8 @4 {& E; h. f, d2 \* E0 g
  speed     ;; the speed of the turtle. a2 k3 y+ h6 j, n9 E
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
+ ]# h+ `! F; t( P  wait-time ;; the amount of time since the last time a turtle has moved
9 N- h% f- F" ?& W]5 C) ?' S' B! ~
2 o! A  {/ U- V! k# ^; z. R9 n0 ~* Y
patches-own4 n3 ~  ~& N" a% M0 J* o
[3 Y/ R: P" K$ k) \8 R
  intersection?   ;; true if the patch is at the intersection of two roads7 \, g' m1 l$ r3 C
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.- i% G1 ~/ r5 m. X2 q8 Q+ x, l
                  ;; false for a non-intersection patches.+ V* O5 l& _' R; H& O
  my-row          ;; the row of the intersection counting from the upper left corner of the& {, Z: W! z& P: U0 m, \
                  ;; world.  -1 for non-intersection patches.8 ^& h$ \: i( z
  my-column       ;; the column of the intersection counting from the upper left corner of the+ R+ o% I' i* f% p# s% u
                  ;; world.  -1 for non-intersection patches.8 O9 s8 Z# b5 U0 U
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches./ z; d" P3 I( p+ _. ]
  auto?           ;; whether or not this intersection will switch automatically.
" R) F- f# ~  e0 q                  ;; false for non-intersection patches.* U- D! j0 |: Z3 X- K. o2 c. ?8 G
]
" N3 M+ E; h1 B
) J, I+ y- [3 \, t
% R+ I+ U- m* U0 j; R/ i7 ~+ F5 n;;;;;;;;;;;;;;;;;;;;;;9 W6 h# c3 J  T
;; Setup Procedures ;;
# s4 u3 k- H9 `;;;;;;;;;;;;;;;;;;;;;;
- P# l. Z  W% P5 k! a+ Q) V2 b6 q" M
;; Initialize the display by giving the global and patch variables initial values.) K9 K/ n" P  K' B8 i8 M
;; Create num-cars of turtles if there are enough road patches for one turtle to- j( s# M7 e5 i7 `% \
;; be created per road patch. Set up the plots.: d2 D' L& V3 S
to setup% v+ p% I2 ]' A0 u9 r$ N9 x
  ca9 j0 d* J3 D$ [& X# [
  setup-globals; g1 W6 G: a9 w. ?% ?+ c
, T  m/ k0 Q* r6 X
  ;; First we ask the patches to draw themselves and set up a few variables
! B2 A( L  v  k% z& ]8 X  setup-patches
# C7 l4 i5 U# ^! W% ]7 Y  make-current one-of intersections' ]$ Z. M; N' x5 V1 f. D
  label-current- l: \2 B% v& r5 {( O
2 i+ R: i1 x" z: X- @- u/ B& C9 R
  set-default-shape turtles "car"; ~# B/ H6 B, `- K+ t$ G$ q

; R1 w' f, D1 W# J2 b5 b! G, x$ c# m  if (num-cars > count roads)
2 a* d4 m. ^% b" A- s  [7 w4 K( q4 g$ k9 F: i( t+ z
    user-message (word "There are too many cars for the amount of "
/ h. {' N- w, P. i- H! D: R. d7 X* o                       "road.  Either increase the amount of roads "
+ D2 X, B2 O+ c+ \) T! J+ K                       "by increasing the GRID-SIZE-X or "  g1 B5 Y" v+ z9 e  N
                       "GRID-SIZE-Y sliders, or decrease the "
4 F" G$ q+ e! o4 x+ p* B5 c6 M                       "number of cars by lowering the NUMBER slider.\n"
* n. b; b4 w* L$ I4 p                       "The setup has stopped.")
  N' V5 r3 {6 _1 s, F    stop: L! M+ C% K0 T: q& O" D5 F
  ]6 g8 [- j6 L* p

1 |$ g" B: T6 M# B' N1 Z  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
* X$ N9 @+ N$ C3 x% [9 U  crt num-cars' v: R2 C6 v- e" }# B1 n; X% L
  [: b0 P  k& w3 Y* f1 U# k
    setup-cars) G* s$ g; s* Y; M
    set-car-color  F3 K: c$ s+ k3 Y  q# N6 w& a: n
    record-data: d6 C# p% Z& x8 W3 h
  ]# p, g1 F" k  F. h5 P

4 L7 i6 w' i: s0 ]  ]  ;; give the turtles an initial speed
( ?- I* D' U$ V" S! C& [- g  ask turtles [ set-car-speed ]% }1 o$ L+ y) [
7 d5 t' V" p+ l9 X. E+ o6 L$ z
  reset-ticks
" a, M1 G# S1 w2 g  j+ bend
2 K) q$ D0 d6 m8 p5 T* C3 Z: c, q, h1 V5 s' {0 l/ ?
;; Initialize the global variables to appropriate values0 `" b( ?/ B7 x4 A& ^% c4 _* B! }/ ~
to setup-globals+ s, u8 e/ n$ A: s" N  b
  set current-light nobody ;; just for now, since there are no lights yet
1 Z% b! ^' d$ ^6 G+ N/ H  set phase 0
7 e3 ?- o/ [5 j- [0 v  set num-cars-stopped 0; |2 i$ m. r8 ^' ?; R; Z
  set grid-x-inc world-width / grid-size-x+ B! K  c7 p$ {$ @( I
  set grid-y-inc world-height / grid-size-y* f- x' k2 K4 |3 c
/ G- [* S0 d4 q( D/ q, w7 X
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
5 V4 {3 [# {& j9 D4 g% L2 ?  set acceleration 0.099
0 T* q& S) o" y+ y7 O# ?end$ [8 }9 J9 P7 E( N, z( b6 i

$ z/ y$ W0 h" B7 K% O9 m;; Make the patches have appropriate colors, set up the roads and intersections agentsets,, p, l- x3 A; k) ?
;; and initialize the traffic lights to one setting
/ H$ R4 X! `4 F2 W: Tto setup-patches
2 t7 C5 \) C2 j: ^0 z* L; R  ;; initialize the patch-owned variables and color the patches to a base-color
$ Q  |0 Q7 m+ B& |  ask patches0 `2 {+ x/ }' G
  [
5 P4 p6 _" [1 [; Z( X5 d3 W    set intersection? false5 w: x7 K% f! q* ~2 G7 }0 ~
    set auto? false
) G3 c' B5 r# ~2 y  c$ n    set green-light-up? true
1 V8 m3 m, Z, I. {, {6 x0 t% w, h3 B    set my-row -1; r& _1 ?" G, G0 R& h4 c' ^% r: ?
    set my-column -1/ `4 z- s5 K# X
    set my-phase -1
1 F7 x4 g' K9 Q    set pcolor brown + 3
& a- W4 Y3 |+ D# B/ \  ]) C7 ^. o  c- ~

) |  V9 ?/ q% W- r1 j  ;; initialize the global variables that hold patch agentsets" G+ {: G, p. y9 V# g
  set roads patches with
0 Q1 `0 p- ]  p4 H- F5 ?( e    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% l: q9 [7 \! B6 B    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' L0 E) L) ~1 c) _# o7 X- C  set intersections roads with
( w  f2 h( S# r4 K    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and, {( N  F, A: I' T* w% T
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 O  T: A  [4 n# C9 E4 G; F
, x  m% ^. V5 q2 V  ask roads [ set pcolor white ]
: W; m$ F/ ^- t. q6 G; y    setup-intersections
6 J7 S% m/ }9 X- Y8 \4 L/ j* Bend& d, }3 ]6 Y5 [; t
其中定义道路的句子,如下所示,是什么意思啊?
, t' N) m/ I" t& t+ t: M! V0 f set roads patches with6 g3 z6 }8 o6 g3 D  u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ o6 u) |! T* b) m4 B( n7 S
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' v1 \- I0 `4 q/ R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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