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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。
5 a' V; P8 E( a2 t* Onetlogo自带的social science--traffic grid这一例子当中,1 {2 b7 C2 H+ R& E$ \- @. ~
globals2 e" t+ `/ m, E* Y! q. L
[
: }, u6 H, B5 m  grid-x-inc               ;; the amount of patches in between two roads in the x direction; i; P: B, V) x4 K$ G' ]2 @  n
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
' c: X% T9 [' I8 `9 m5 f  n) |  acceleration             ;; the constant that controls how much a car speeds up or slows down by if* V7 P' y" l" D; N3 p
                           ;; it is to accelerate or decelerate2 \/ E9 |. ~( c% O/ _! }5 n4 S
  phase                    ;; keeps track of the phase
! ?/ r8 y7 ?+ f  p9 n( A  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
/ h8 r1 x) d8 `8 @! X  current-light            ;; the currently selected light4 W: G2 W; m' y" H8 ~1 X3 V; p
" D7 ]- F2 S; L! `( p8 Z0 w& b
  ;; patch agentsets8 z2 j7 @1 ^$ K! w; P5 s; \
  intersections ;; agentset containing the patches that are intersections* x' O% H/ N! w/ y, |
  roads         ;; agentset containing the patches that are roads4 ~& @9 d& X9 c
]
. x: d3 `  R3 s, s7 A) ]" N* u
8 M3 l  b2 z. q9 ?8 \( j% a6 \turtles-own/ E9 o6 X( K8 u1 Y; S& k
[
: j( Z! g: e9 j' X& Z  speed     ;; the speed of the turtle
# ?! J3 j$ s7 t- g+ H  up-car?   ;; true if the turtle moves downwards and false if it moves to the right5 |3 V7 H- T1 \6 `  B- l
  wait-time ;; the amount of time since the last time a turtle has moved; }, T! D6 j1 O: y! `
]3 N; ~1 y" m, h
) r# J. r9 k2 q4 Z: l% @8 `
patches-own
( s" ]4 w# z# ^: q% \[
& H4 g% |" C. O  intersection?   ;; true if the patch is at the intersection of two roads! |# j" b' [1 \1 _4 C( y
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.6 u. a! A; D9 U, I
                  ;; false for a non-intersection patches.( @" ~- `8 V; c- k1 m
  my-row          ;; the row of the intersection counting from the upper left corner of the8 n2 E. s) @  k" C/ E
                  ;; world.  -1 for non-intersection patches., Q! c* v9 z1 k$ T- O
  my-column       ;; the column of the intersection counting from the upper left corner of the
/ e* s1 f% s* c  Q8 {) B$ e                  ;; world.  -1 for non-intersection patches.
( _. m  m* z/ }" h/ z1 `  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
& u$ g9 \# I/ e4 S  auto?           ;; whether or not this intersection will switch automatically.  A! R0 ?3 d% y1 {
                  ;; false for non-intersection patches.
. N, @, O# \' O$ s]4 W0 ^. Q8 R# ]0 B
+ {9 N; d9 o4 U0 ]
, x4 U- t. g, }' P' M1 E
;;;;;;;;;;;;;;;;;;;;;;' W$ x( j- s. O  {
;; Setup Procedures ;;
5 E( b6 O/ e, R, H% Q;;;;;;;;;;;;;;;;;;;;;;
0 Q$ u  V+ S- D2 g0 k8 ]& A0 l: h) H1 A% ^3 p
;; Initialize the display by giving the global and patch variables initial values.# V* X- A+ E# Q$ ~# e
;; Create num-cars of turtles if there are enough road patches for one turtle to
  M5 _4 f/ O  l& _; ]- I;; be created per road patch. Set up the plots.- N  |8 W9 {$ V3 W+ }' G+ n
to setup. \& d( }. P% w1 G) o. d
  ca; N% ?9 A: V3 t
  setup-globals" h- _* r; v3 B% C+ e

3 B8 C' f* i7 b0 |* u  ;; First we ask the patches to draw themselves and set up a few variables. w1 z3 k4 }) b& Q  u
  setup-patches  K+ e* }4 R. f. N" H
  make-current one-of intersections
- `' V! ]) L. R  M9 Y+ R  label-current
% p9 Y# a5 R; D# v& _6 j- A1 }
* F# y1 b, d# Z2 i0 C9 \  set-default-shape turtles "car"- t3 m5 Q, q& _3 j( u
8 z9 `7 l6 A% A( Y# h3 I/ K' i
  if (num-cars > count roads)
* b; J6 q& z, c6 m  [% z5 ^* J& F' q5 v7 z7 P8 o' S
    user-message (word "There are too many cars for the amount of "
* U) y+ @& ], Q, h                       "road.  Either increase the amount of roads "
  ~% Q0 u6 v- u  O1 h& O                       "by increasing the GRID-SIZE-X or "% R/ X+ Z/ s* n2 N7 h- w2 S
                       "GRID-SIZE-Y sliders, or decrease the "
; F; e+ B7 [% Y. V7 Y                       "number of cars by lowering the NUMBER slider.\n"# L) g; {9 J  @" J
                       "The setup has stopped.")& i- t) i* Y5 L/ T
    stop
3 ]4 F( q1 d) L# Y4 D% y* B* T' H  ]% t9 \' Q' P1 v0 I2 R4 K3 T; _! ^1 z
7 m% N$ o: |2 H: g) H
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
: I+ G2 g: X, j. S5 ^7 X( e  crt num-cars
+ x, R( J( `( j9 u; r  [
2 f1 E5 ?; I1 _3 X* a! n& j7 P    setup-cars
/ ~, Q0 L& E$ o" l0 J+ k    set-car-color
' Q) f, {$ }" p3 q    record-data( i7 J# Z& \6 P: H; h# u' v) R& F
  ]! H0 o2 p$ e& U8 j; X8 f
0 K4 ]3 b' j( @* ~( R, ?
  ;; give the turtles an initial speed, i- T; r0 z' T0 h8 b% e$ u  x5 }
  ask turtles [ set-car-speed ]
5 i$ b1 P# g4 i! V: L/ {; T
* W, a7 |9 Y/ m) p$ K4 B0 v  reset-ticks0 B0 R% N4 B4 Z% d
end  g1 A) u5 I, S: m, G$ I7 S; g
8 J. M0 G  m% R, a3 p# ]& h
;; Initialize the global variables to appropriate values
7 B  n0 O( X% }to setup-globals; S; t& N  x7 G* R
  set current-light nobody ;; just for now, since there are no lights yet
  M- h; e. l5 u1 I  w  set phase 0" v* q) e3 o2 `  R& j$ Z& H
  set num-cars-stopped 0% `; E/ l! C! N- ^. T
  set grid-x-inc world-width / grid-size-x4 y1 I. S, k. I& h& _/ d
  set grid-y-inc world-height / grid-size-y
( j, l  k, J; j8 G: |1 R2 t' f" u! m( A6 n' I, k& b9 y
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary5 o6 I' m4 g1 H( U' |& g/ {
  set acceleration 0.099' ^$ P7 m7 q; Z7 C
end
7 s- ?& K- r- A
0 U( h* @: s4 f# r. t;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
5 H8 t: r) F+ D5 [;; and initialize the traffic lights to one setting' S9 @; Q: V/ J6 A
to setup-patches$ t$ p& F+ Q3 r8 Y( J. W5 F
  ;; initialize the patch-owned variables and color the patches to a base-color
7 v, d' S: C# Z  ask patches
8 f& s5 p6 Y* y' ?' l6 G  [
  c- v0 |7 @2 m1 A    set intersection? false+ C# ~6 u1 `; }
    set auto? false8 a7 p  Q" X- ?
    set green-light-up? true
/ W2 J3 Z& `0 w0 ]    set my-row -1
( O. b$ t5 [1 `    set my-column -1
% e% a- m& z' a" j    set my-phase -1$ ^, m/ T6 o- @2 _( H, ?
    set pcolor brown + 39 @$ `) \% f2 y9 O1 L2 r
  ]. [# _6 o6 F* D# o3 p  K

* R# y) E1 o3 [  D9 E% N0 i  ;; initialize the global variables that hold patch agentsets
8 c, j3 b4 y/ c  t& f% j  set roads patches with
+ S7 c, V, ~- g  R2 ^8 j9 S. M) g    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% d3 Y; Z1 z# U0 P+ x7 K    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 u# m; c8 d0 T. }  set intersections roads with
' X0 j' ~2 w8 t7 M1 M  B- R    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
2 Y/ P( U5 B& V3 g! Q8 U  b) t" d    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 C( Q+ s( q3 E2 p7 y0 f
' {" G. f1 M; m9 f3 s9 R$ E6 `
  ask roads [ set pcolor white ]; y; q9 f- A9 _7 q' X- V! t: M
    setup-intersections
+ C* l& \3 G  N" ?" [end; ]1 d9 l) o1 v, Q" N) U( c! O$ n
其中定义道路的句子,如下所示,是什么意思啊?
: |2 Q$ D! E, G; X. F set roads patches with
) S5 G) i' a+ N$ P/ B    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! k9 F& l! `- r$ y; A- q& y- m    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# h( i. O! l: w8 K9 r0 T
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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