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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。
: z' l9 g2 [! {7 M' y0 D( @netlogo自带的social science--traffic grid这一例子当中,6 L5 W% h( U: q3 B
globals& K$ J5 p6 \$ A* e5 P; x6 A
[
; f0 E7 K# H0 R4 b. M2 n  L  grid-x-inc               ;; the amount of patches in between two roads in the x direction! F, C  i5 e" [" i8 T! Z& K. n
  grid-y-inc               ;; the amount of patches in between two roads in the y direction6 U8 E7 p3 ]/ T
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
3 J1 L% j8 N% n! J1 [5 H                           ;; it is to accelerate or decelerate$ T4 T8 p, A* g, e& H! U
  phase                    ;; keeps track of the phase$ [+ n' n  r+ Q+ s: Z) ]
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
( c) d% R' r2 g9 l" y& H% k  current-light            ;; the currently selected light
5 x4 M; M  P/ _0 G* m2 d& A* M" N0 c+ y2 k0 w! b( |
  ;; patch agentsets6 N8 Q# o2 w( g! H
  intersections ;; agentset containing the patches that are intersections7 W2 U0 a1 l$ T; R3 o
  roads         ;; agentset containing the patches that are roads
8 \8 V  _. {0 E1 I9 @% f$ s]
# G( G- x+ L5 B  p: b
$ {% D  o! }7 C& ]turtles-own
* i! i' I  |& p5 M; i[
# }: \! j5 S8 K  speed     ;; the speed of the turtle) d" X0 N  j3 H( V7 J
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right  Y. _- l' ^( V3 D. g' _
  wait-time ;; the amount of time since the last time a turtle has moved
5 J/ ]- @) n( `9 s* t8 N8 q( F6 w]
2 ^2 `  x$ I6 r+ L% R$ Q( t5 z$ X8 R
patches-own/ H  k$ n5 o, X! ^+ u7 r2 n
[
6 L: y0 F: @- l: _  intersection?   ;; true if the patch is at the intersection of two roads. o! n) s6 t3 Z2 O
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
6 O$ F+ J* Y! a$ c  i) {, @& ?3 x1 A                  ;; false for a non-intersection patches.& v# @* M) G' v: ?% k
  my-row          ;; the row of the intersection counting from the upper left corner of the9 C) d8 R& g) z9 x. j  C
                  ;; world.  -1 for non-intersection patches.
& |# i; M& Y# @/ y$ [; Y- v  my-column       ;; the column of the intersection counting from the upper left corner of the! O  U- ]7 `; |0 N% ]
                  ;; world.  -1 for non-intersection patches.  Z) z. z+ z1 S! Y7 R: b
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
/ G" _% d% s/ H  R2 G9 ^3 p  auto?           ;; whether or not this intersection will switch automatically.
4 n+ M/ Y. h4 ^) D                  ;; false for non-intersection patches.! ?; L# u4 c, Q$ G; s' G& v
]
/ L- b4 a7 H2 `: [/ _  G  m) a5 ]  r2 v  n4 ^

3 L6 G  G4 B7 Z8 T$ S& _0 H9 h;;;;;;;;;;;;;;;;;;;;;;
: S0 _$ r3 t9 L( y6 z& k. W4 U;; Setup Procedures ;;0 R% }5 Y% W* p( h! |2 Y
;;;;;;;;;;;;;;;;;;;;;;
7 `5 Q! L  Z  b; O" W
, n3 z9 F% L. q0 |3 v  ~$ e* r;; Initialize the display by giving the global and patch variables initial values.
- T, \* t, }% r- |  o;; Create num-cars of turtles if there are enough road patches for one turtle to( r: w7 e7 t9 d4 j+ u7 {
;; be created per road patch. Set up the plots.
; _9 Q9 ^2 p$ S0 V9 ~; E7 fto setup
+ p9 e, H1 ]7 S8 l8 A' Z& a  ca
$ `3 k+ `6 ?" Q4 f- \1 t  U- [  setup-globals
( Q( s+ O8 H$ Q" M7 B2 v6 v8 `2 B; ]% l0 s  c/ o
  ;; First we ask the patches to draw themselves and set up a few variables
9 g: m7 y9 o' ~" W8 I4 h; T  setup-patches. L8 a' j6 T+ I3 I; `  E+ m
  make-current one-of intersections
8 g  b" v5 a# m  label-current0 {% g# D* J* D8 c3 w
5 H0 _7 s4 V' t7 _  N! J5 r  O
  set-default-shape turtles "car"
5 e4 E5 m2 o6 x& R8 y$ X2 @0 C0 c& J" c/ v  |
  if (num-cars > count roads)+ i4 g& ~9 G5 [+ `
  [
& ]; g  X8 l3 ?" @, \: k! c    user-message (word "There are too many cars for the amount of "
+ o! B. k% `+ @6 D8 a, T                       "road.  Either increase the amount of roads "
2 [6 d+ U9 X% y4 g                       "by increasing the GRID-SIZE-X or "( I4 }/ [! |- e) q8 F: E
                       "GRID-SIZE-Y sliders, or decrease the "
7 ?3 N. N6 c3 D6 R; _; ~                       "number of cars by lowering the NUMBER slider.\n"' r; Y& v: @! V: J" y
                       "The setup has stopped.")4 X" `4 f5 H# k& B  o/ N7 k
    stop
2 a" x  I2 H) u; N# F  ]9 t2 C# A/ t. |$ R
3 }+ K, F; [( e5 n. z
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color6 H3 M% ]( Z- {6 l! B+ i
  crt num-cars- e4 W2 d! b2 \. T; J0 D
  [
: x0 L9 d( B8 A    setup-cars+ t; t& l. Z. f8 C7 y) _* G
    set-car-color7 i5 R0 Q3 d) b& l1 r; w
    record-data
3 s5 o" S7 ?% ^- r! F" X" g  ]
% }- h/ E; P- {
- ]- j7 Y& b7 D9 H- X9 i; Z  ;; give the turtles an initial speed# p2 E  l1 Q8 b2 G: z" J' l
  ask turtles [ set-car-speed ]
* O5 P) g9 |* p! E/ H9 T1 S/ F7 ]9 c0 ~. L
  reset-ticks
- g- m$ |# P4 }' t, fend: ~/ A4 Y) F6 ?$ z0 Z

6 D# A, `7 t' J;; Initialize the global variables to appropriate values5 ~! K: Y% z/ F
to setup-globals
. Q7 y& @, w. J; j% j4 y2 B  set current-light nobody ;; just for now, since there are no lights yet1 I5 Y- ]" o$ d# b- {+ a+ Y
  set phase 0
' v0 n& Q9 `3 c- o  set num-cars-stopped 0
' o) u, h# P8 D* \, a  set grid-x-inc world-width / grid-size-x; c$ R, i: ?( H4 O; ]8 ]
  set grid-y-inc world-height / grid-size-y
( d% `2 K* F+ v2 Q+ t* t9 B! l' _+ E( Q1 ^2 V
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary! {* L' g5 |: J% U& o  m: p, a
  set acceleration 0.099' ~0 w/ @: }$ O' g9 u
end
. l# A6 M& m9 F
0 x. _5 \  S5 S2 c! K;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
$ @! @# ^: ]% I7 j2 P1 w;; and initialize the traffic lights to one setting/ |+ B8 y+ J( R1 y4 }
to setup-patches
; @# y+ z3 K  u5 ~0 w0 O9 x  ;; initialize the patch-owned variables and color the patches to a base-color# K' \3 ^" h4 L- j, y
  ask patches- V1 F* A! @* l6 G) O
  [4 p& \# T$ u' k* ^2 K9 N1 m" c
    set intersection? false
4 v5 i+ ?; l7 T1 L    set auto? false9 H( `5 n) N# P/ p3 z% D
    set green-light-up? true. x3 T5 \: m) V# F& K( \
    set my-row -1
4 E$ X' U. h( U    set my-column -12 }: Y' i1 S, I& u# N
    set my-phase -1) j( X/ p9 ~' M
    set pcolor brown + 3: y; ~! D4 ^2 K* p4 A
  ]+ G9 N( m% b  }. W, E) o& }
  d7 P( F, y* @8 N) k
  ;; initialize the global variables that hold patch agentsets
2 V7 ]! @6 M1 \. E% U$ s4 ^  set roads patches with9 g+ ?# G. [, X. @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ o, t6 q0 n: ]3 t/ g3 t
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 p1 y; S" D3 y& n8 e, J( I  w8 \  set intersections roads with6 L& a$ E8 |4 j
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and* t) w9 H' U) Z7 ~2 h# I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 c+ I7 q# ~% M$ s3 X* D
. N5 K  U' b  @: Y" N
  ask roads [ set pcolor white ]
1 G: V: {  r1 }    setup-intersections6 J6 y1 V- ~: d
end) B# E2 u" }+ s) a
其中定义道路的句子,如下所示,是什么意思啊?
% p. m0 a$ [* k" S  @4 Q set roads patches with
( H0 s# G8 f3 a6 l- k9 }( Z: Z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ ]* g! n2 q& x( |2 i, ?    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. F- W4 H; Z  @! S8 \0 w, V4 Y3 i) 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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