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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。
6 B& }! ]: t( j( \8 T  ], \7 ^3 ?+ onetlogo自带的social science--traffic grid这一例子当中,0 {# D; A, p8 c+ z& K; V8 X
globals. `' t* }. y7 U; x1 \* a5 U3 P
[
5 m- `& t* Q" S) T# Y  grid-x-inc               ;; the amount of patches in between two roads in the x direction0 \* ]- |- @8 C, r9 G
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 e* ?  j4 N# B: |( @# Q/ I  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
3 }% T' d2 W3 a* K1 k" [                           ;; it is to accelerate or decelerate
- g3 z# H  x+ O1 {  phase                    ;; keeps track of the phase
$ u5 e% E( l- U( c0 v4 [  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure, ?) \- Y% C" v. n' ^
  current-light            ;; the currently selected light
6 E7 Z* b0 c! O5 x( D& `  v8 A6 Y3 ?0 e) D% r0 R
  ;; patch agentsets! D2 V8 P5 U  T9 ^
  intersections ;; agentset containing the patches that are intersections
1 i; x" H2 a7 G2 s+ P7 C. J  roads         ;; agentset containing the patches that are roads
3 I* P$ E8 j9 y, ?4 C]6 m  H6 B: ?, S$ N$ ]/ f2 I2 z
  G2 E* Y* X( l$ h
turtles-own5 G/ W2 l  \3 v; N5 `6 @4 z2 O
[
# c: b1 F  B# b  speed     ;; the speed of the turtle  P: n# Y3 r+ n# Z0 D/ b- l
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
: o% k1 v% d% `- y  wait-time ;; the amount of time since the last time a turtle has moved6 o( t6 G; X: T% |- g" ?  J
]
. k+ q3 ~5 U6 o# _1 u4 D- U$ O/ ~+ e+ _5 c  ]5 G& E- e4 K5 k
patches-own! E) B& q+ n, Q, }
[
4 p" ~. E$ e9 _+ @& U7 m" u" [  intersection?   ;; true if the patch is at the intersection of two roads
% R+ D4 t  I  c. I: C; ~3 a3 {  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
. ?) D& N. R1 b" v( K                  ;; false for a non-intersection patches.
$ o5 D# C8 Q/ z: A* ?  my-row          ;; the row of the intersection counting from the upper left corner of the
. Z6 n2 |  r# c. N9 q  \# W9 A, P                  ;; world.  -1 for non-intersection patches.& f: U5 r- X. H8 Y' X
  my-column       ;; the column of the intersection counting from the upper left corner of the4 G) n7 A& [0 e0 H2 N
                  ;; world.  -1 for non-intersection patches.
" M  d: Y1 r9 T3 N6 n6 `& d  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.4 F# Q9 j& \7 T7 b! y% a8 E
  auto?           ;; whether or not this intersection will switch automatically.
* |6 n! U" m: V6 Y                  ;; false for non-intersection patches.
3 x% c7 S. G0 \# D3 Y4 N]
4 n8 A' h' Z5 C. M2 l5 s+ @1 ?- v
8 t% W, b! K2 C4 ^' U+ \  q! ~7 h: O0 o) {/ r& P# i
;;;;;;;;;;;;;;;;;;;;;;
. V) h0 E. S4 i1 n4 N9 c" E;; Setup Procedures ;;
8 r! \5 u( O' @;;;;;;;;;;;;;;;;;;;;;;1 k' G5 U, [0 }6 d

6 x) J% R1 H# d2 t;; Initialize the display by giving the global and patch variables initial values.+ G8 r% v* b. N) S, n7 v. Q
;; Create num-cars of turtles if there are enough road patches for one turtle to( p" P  H4 d3 s) S
;; be created per road patch. Set up the plots.
: U6 f% L* i( {# t/ zto setup
* o% X* h) _6 L  ca
7 q! l. p* ?3 E  setup-globals
4 E* ~! B7 ]+ K* l8 h* R3 |0 H5 l& e" T1 m9 t+ c- A
  ;; First we ask the patches to draw themselves and set up a few variables. L5 ~3 m  m" w
  setup-patches
5 c' W+ q. y) m  N- E! `; X7 w/ ~  make-current one-of intersections
) X1 D$ M4 n, ^2 x, a0 W  label-current) {' x- f( E! X& F' o7 e; ?8 Q/ B

9 B! y+ q/ p* B6 D! p+ t$ p  set-default-shape turtles "car"4 o  X+ _  l9 y+ o

; [1 {# F' i8 A5 _, ^; l% j  if (num-cars > count roads)
. P% O) j% B; c3 d9 w# |. |  [9 l7 n3 Z( B. \; S2 B" z5 C
    user-message (word "There are too many cars for the amount of "$ s% k- f% m# J4 P( S3 A& k
                       "road.  Either increase the amount of roads "
# E; J% c; Z9 c) T4 x  b5 |" T                       "by increasing the GRID-SIZE-X or "4 b# a4 Z2 y( F2 y3 j! w
                       "GRID-SIZE-Y sliders, or decrease the "8 E* @! j& `/ w! Y
                       "number of cars by lowering the NUMBER slider.\n": X! p- k; l3 [: E
                       "The setup has stopped.")
' V- @) v8 N) [    stop7 i; L8 g: a0 S$ u
  ]
# y% I: u3 ~2 Y1 j  B1 M" B( ~4 }2 ?8 ~
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color4 _. ?( F0 D+ w* A7 \7 `
  crt num-cars  ~2 s8 N, N, M6 t5 u! p8 ^
  [/ `* \% W" A7 J
    setup-cars
2 t. Y2 F+ ?4 ?, l* Q    set-car-color- C0 j! K/ M5 C7 C
    record-data
# `' R- u" ]" D" o  ]" |& L) V& l$ X& n
( P4 m8 P% @0 X! D, U' h
  ;; give the turtles an initial speed; [( c- ^( H1 @4 F
  ask turtles [ set-car-speed ]' C) N/ w9 I. P- x

" \0 Q7 M. i7 O, ?+ @& @  reset-ticks, F: R  r! g9 F+ G
end
& K# _1 T4 Y" \: ^+ G  r0 z2 u8 T% B& \* u/ _$ _3 p: a' p' f
;; Initialize the global variables to appropriate values# H% D# |6 |, d3 X8 G
to setup-globals; n4 {: \8 d9 G) z9 p
  set current-light nobody ;; just for now, since there are no lights yet
3 z$ z- v5 ^" I  set phase 0. b$ \$ I0 i9 b/ J- N
  set num-cars-stopped 08 d) p0 Z/ _6 d/ J( e0 ~+ `
  set grid-x-inc world-width / grid-size-x
- c8 w4 X/ G) u& E* x3 p& o2 b  set grid-y-inc world-height / grid-size-y
$ V5 m5 f( ~. T0 |3 ~, V9 f
" l" N* w* T* w7 i  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary' ?1 [. p0 `- U3 g( |3 d1 K# N: I$ O
  set acceleration 0.099
2 T8 U# f: U9 k1 Xend
1 t; V1 \# v7 x( J
, y+ [. |% Y3 d- \: Q3 g" g. W! r;; Make the patches have appropriate colors, set up the roads and intersections agentsets,- s8 h% n2 b4 a: v( M
;; and initialize the traffic lights to one setting5 l5 ?* B3 p5 b2 r8 I
to setup-patches
4 O, w1 l+ g4 N( c2 _  ;; initialize the patch-owned variables and color the patches to a base-color
' v5 P& {1 T0 q: I$ @  ask patches
. ^8 o, X( \1 k' w- U6 R% b" J  [
" D- N; r, _$ n0 N4 ]! E3 Q8 q; P, m    set intersection? false+ l$ \4 [% c( B3 m5 ?
    set auto? false. p% E  r. ^3 R9 E% S
    set green-light-up? true
$ U$ A3 m, c' [3 C# m    set my-row -1% S$ c( F3 ?+ K/ B3 l2 H" o
    set my-column -1! U7 d- i9 v. w5 }7 p( {$ C, H
    set my-phase -13 ^. Q$ {% F9 v, Q/ A& N# y
    set pcolor brown + 3' J9 ^' u$ M- ^- J. `% u
  ]
# M* p8 R2 \2 O3 S! f% l+ g- R$ F0 t9 I
  ;; initialize the global variables that hold patch agentsets
% j/ P6 U, u- \  set roads patches with
9 \4 n3 L# {7 j7 u1 Z3 f    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# K. p" a1 A4 w3 I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 d" m% a, |2 O# E
  set intersections roads with% y  X' G9 b  {1 [
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
3 y2 K0 {7 k0 P5 g  X$ k; i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 `1 l( ^6 _7 r' t- o0 q; q
$ Y+ B& v$ Y' A$ P# J) F7 ]
  ask roads [ set pcolor white ]
+ P5 `4 _) R- A& ]+ K# y8 h    setup-intersections
; t7 l& `4 L. I5 z2 g6 N  |, oend5 A0 q5 D& p4 |2 U$ P% p9 X- q
其中定义道路的句子,如下所示,是什么意思啊?
2 ]3 [# \* q. m set roads patches with  A) M8 g: H3 z/ m/ p( T
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, l' x! b; S& y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# `0 k6 v0 R0 b: H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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