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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。
* b' R$ p/ r% V" n7 Anetlogo自带的social science--traffic grid这一例子当中,5 S8 D4 H$ C* [0 U5 N
globals
8 o! T( z& R* Q  {[* M5 D6 T% m: r* v5 P5 o% ^3 e
  grid-x-inc               ;; the amount of patches in between two roads in the x direction1 F; ?! U! r9 s; O, A; D, G
  grid-y-inc               ;; the amount of patches in between two roads in the y direction) k: b' u" t2 ]3 ^- ^
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if3 ]6 i- b$ G6 A) F  ?* c
                           ;; it is to accelerate or decelerate7 o! G  O9 T4 H
  phase                    ;; keeps track of the phase
8 a# i$ j5 Y+ Y# q- [  p  k, \  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure9 @/ C' H3 b+ G& d" T
  current-light            ;; the currently selected light
7 Z) @- r, Q+ v& I! O! S9 P% e+ l8 z0 A: U$ F4 @) O
  ;; patch agentsets3 Y3 n" U0 m  y0 y
  intersections ;; agentset containing the patches that are intersections, O/ |8 F, |. R
  roads         ;; agentset containing the patches that are roads4 \2 [7 m7 c3 H8 H: T
]1 A+ l) G# ]9 ^4 k* C' d

& \- }, O1 ~0 iturtles-own7 g6 O: E6 p( ?3 ~( Q
[
2 B; c: a! T6 I0 k# W. D  speed     ;; the speed of the turtle- W( W2 L! N, I/ v
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right, M; g7 o( n: H6 P( t/ Q
  wait-time ;; the amount of time since the last time a turtle has moved/ B& \, r" V: l
]" t/ v& \) x+ A5 ^& o

% W% I. D  w0 F2 d) B% Spatches-own# U, U/ ^' [1 `3 U0 ?' s
[: \+ [) w& d6 t) \+ V
  intersection?   ;; true if the patch is at the intersection of two roads
6 C! ?6 N; _$ D# j0 }  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.0 }1 |; B7 n* b$ n9 ?, {* M: g/ t
                  ;; false for a non-intersection patches.$ p& u% V$ L3 ^+ Z* i6 ]
  my-row          ;; the row of the intersection counting from the upper left corner of the
: B; z8 D' o1 p6 U# X7 Z* b: I3 f2 f                  ;; world.  -1 for non-intersection patches.1 T9 Y. X$ g/ G7 w4 Q/ e2 O
  my-column       ;; the column of the intersection counting from the upper left corner of the  p$ O# S7 I0 x4 U6 t) ~1 d# w
                  ;; world.  -1 for non-intersection patches.5 @2 {8 [! o7 P
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.4 ]: y# H4 ~7 L3 @/ n
  auto?           ;; whether or not this intersection will switch automatically.
" W+ d" X) Z/ e* A/ q- P                  ;; false for non-intersection patches.4 d( I* \3 t8 K
]6 X0 J+ g) i& K( k

8 E( y- _" _/ H% s! U# O. x9 w, L2 K' p+ U- s5 e5 _
;;;;;;;;;;;;;;;;;;;;;;+ g4 a+ O7 @+ C# l8 l3 r! T
;; Setup Procedures ;;/ [' v- h+ l# O  D
;;;;;;;;;;;;;;;;;;;;;;6 C9 K  d0 Q  [+ t8 K

+ m3 S3 [& A; Y$ E/ R  o;; Initialize the display by giving the global and patch variables initial values.; w" {+ }: S9 R' W0 A' l
;; Create num-cars of turtles if there are enough road patches for one turtle to+ p- _/ M2 d- P/ f. S: p7 I
;; be created per road patch. Set up the plots.: w9 I) e! b% v
to setup4 m5 h3 l2 z7 `6 k
  ca
& n: K& u$ {$ Y+ I7 l' q3 J, g  setup-globals
  i  g  t% V/ \% v7 x/ a4 ~5 b$ e
  ;; First we ask the patches to draw themselves and set up a few variables# f3 U6 Y/ z3 x7 b
  setup-patches
/ \1 g$ @* k6 f" I0 a  make-current one-of intersections
3 S' {* G* n0 {) ?( A3 }8 H  label-current
; R$ h+ t( ^! [/ U/ ]& \
8 n& p' B$ \; H' W5 C- O- w, w  set-default-shape turtles "car": ]& o0 T: K" H

' ?7 Q8 j* W# {0 D, C  if (num-cars > count roads)) R. c/ I1 k; a* w& r. c
  [
% @- n+ |% w% @( w    user-message (word "There are too many cars for the amount of "
5 Y! K% g+ {* z0 ?' b                       "road.  Either increase the amount of roads "% ?8 {5 q, `9 H1 s
                       "by increasing the GRID-SIZE-X or "# b  @" o3 C+ p* `
                       "GRID-SIZE-Y sliders, or decrease the "
$ W4 ^3 e3 X7 k7 }" R                       "number of cars by lowering the NUMBER slider.\n"
) i2 o) k, N" |" f3 t& l$ z                       "The setup has stopped.")) f1 Z- g, K) u4 t2 n7 z
    stop# H" ?: X# ~5 }; C% J% l
  ]
8 k) u) n2 y3 I6 o9 M1 G
& \% u9 b! s4 l4 H  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
3 Y! o  l6 x" \/ `6 w9 h. R  crt num-cars
* N+ C1 V; l- {" g  [3 a; k6 B4 w: B. c8 D1 V$ n& s! L( @
    setup-cars
7 a6 d0 c; m: P9 f" J. j    set-car-color- B$ C9 j" U8 h) G* A  z8 |+ I! `
    record-data
6 A( w4 D4 L. U+ x  ]
' K9 L. a0 x! L9 U; @# ^
# G4 C; ]- K5 w' z5 j  ;; give the turtles an initial speed
" F* J, A0 c! r  ask turtles [ set-car-speed ]5 ]; u; i1 B, ]5 c

1 s. N+ i, ]8 G" w  reset-ticks, E! I& D/ w) w5 w; [
end$ v$ \+ j" R8 _' i2 j
1 U+ }8 Q$ T9 d& q# ^0 |
;; Initialize the global variables to appropriate values
0 k9 e  x3 M7 }: L! W. {to setup-globals7 H* S: q8 v( p( p, x
  set current-light nobody ;; just for now, since there are no lights yet
! D1 Z. t/ Y* U9 Y9 R+ }# P  set phase 0
6 h7 ]7 u; @9 a" W3 @9 i  set num-cars-stopped 0. e6 m  f9 f" w; Q! D( [
  set grid-x-inc world-width / grid-size-x9 [( ^) i7 G) t# V4 x, W
  set grid-y-inc world-height / grid-size-y
- [" ^3 x8 N  k  {: l/ x; w, `2 L$ f/ i
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
( M8 h2 L$ G3 {; R" w% m  set acceleration 0.0995 J$ x* v3 L/ I% B5 L
end; U: h. _; T4 R% P, C$ t. V1 b

2 S; G" }1 v) n;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
; S3 @2 b- n  @;; and initialize the traffic lights to one setting5 U2 I- s) `1 t4 j. W" ]/ e
to setup-patches9 n, ]8 {# V8 S6 Y% I4 }
  ;; initialize the patch-owned variables and color the patches to a base-color! v: K/ V  p1 {; P3 f
  ask patches& C6 F* H5 W4 s) {: j. L0 S
  [% {1 d! Z/ P- d' D
    set intersection? false  T& w3 Y  @( v! J3 \! Y: n
    set auto? false$ q. W2 a$ Z7 L, `# P5 B/ g
    set green-light-up? true
3 L3 v6 t8 `+ U    set my-row -1, B$ R/ [+ e" C" s8 r( Z1 q
    set my-column -13 k0 V. I8 D( v7 v( a) b4 Q
    set my-phase -1
+ y8 A9 D+ N5 j5 L2 q    set pcolor brown + 38 p+ a+ {( G! q% r
  ]" g/ _, h! D7 i* a9 [! N6 r& T7 G7 ~2 a

5 @: D) x1 ]" E- |+ n& i* [, I  ;; initialize the global variables that hold patch agentsets: Y- L. D% y0 S4 e' l
  set roads patches with
9 F! g- b1 |7 M2 |8 I" q% k    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" `6 c7 C6 t$ V8 g! p9 C    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# @$ [0 n! a  c: {! l" S- v  set intersections roads with
' x' C9 q0 [) M" B! B    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and9 y* n# Z. l) Q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 T; ^$ e% F; m  V8 i7 u) Q
: |) [: t7 \% u9 v- d% d  ask roads [ set pcolor white ]
7 j' _# y' h5 O) `% S% H    setup-intersections
( u5 e$ d1 O: C0 |end
4 b- f+ o  M6 G  |其中定义道路的句子,如下所示,是什么意思啊?
5 r+ _4 O& }3 P6 | set roads patches with; X( H( A6 o# [7 u. R2 Z2 r
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 r# p/ `" p) u  U1 F
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" U- G' a8 r# O- s, w
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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