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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。
7 K" A7 }: A- @netlogo自带的social science--traffic grid这一例子当中,
7 p9 M4 f8 B& q$ D7 Q6 oglobals- t" o" m# w& w  r
[5 z. D9 a/ N5 _1 [
  grid-x-inc               ;; the amount of patches in between two roads in the x direction1 X8 S3 \! ]3 g: _" V
  grid-y-inc               ;; the amount of patches in between two roads in the y direction7 y# j) L( Z! @9 [& K. T
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if8 P% |" ]2 A2 t: {% X
                           ;; it is to accelerate or decelerate/ ]& W% S" i0 B* o' L1 m6 x
  phase                    ;; keeps track of the phase
1 Z+ g3 r# j6 z  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure# K- W* f7 g3 H
  current-light            ;; the currently selected light
& z0 u* P7 {' ^  R" @
# o$ x& ]% G9 ?) n- V  ;; patch agentsets
' H0 Y4 t' y( @( q7 v! ~, V  intersections ;; agentset containing the patches that are intersections( L. |4 F; ?  T% j$ {1 s! x
  roads         ;; agentset containing the patches that are roads  u' a+ `; h' C
]9 y+ U6 j8 \4 F3 R: N5 m

7 I' b, A2 {8 u1 f8 _8 J. U; tturtles-own
9 ?5 ?' C- R) {2 C( T5 H! p# p* r' z[' x5 V! Z& q: a! c+ P$ O& N
  speed     ;; the speed of the turtle
, y* Y! m% g  Q+ B0 b  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
% \0 ]- T; @5 I  wait-time ;; the amount of time since the last time a turtle has moved
6 s1 d4 {$ s+ F$ `, H: w. e4 D. l]0 [9 v5 @: b' i4 T- a, o8 S
5 R5 z# h8 O) i, \. ~) i, ~; K) ]
patches-own+ w+ n! f2 U* j; X4 P; y
[5 ?6 c! I& f- I, D( ?* m0 q
  intersection?   ;; true if the patch is at the intersection of two roads3 P/ ?( e$ n! C% t+ k
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
( P- `9 L% D5 Q2 F" |; k: h                  ;; false for a non-intersection patches.! V; J7 w2 w1 n  w9 a3 U9 N0 H
  my-row          ;; the row of the intersection counting from the upper left corner of the
( N2 O, J6 |6 {# Q/ g3 T2 u: \                  ;; world.  -1 for non-intersection patches.6 H6 n0 }3 |0 r& }! s8 A
  my-column       ;; the column of the intersection counting from the upper left corner of the
/ n( x! L. O' |3 g1 N$ B                  ;; world.  -1 for non-intersection patches., U7 \( H0 W: t1 Y
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
" u/ N8 a0 w. Q: ]5 Z  auto?           ;; whether or not this intersection will switch automatically.
$ O- ^- {/ T! a. f4 \* Z' ~                  ;; false for non-intersection patches./ L: Z; \+ X+ M# g
]
1 K* L; ?! T8 P3 \# d7 b) {0 r5 @" Z0 |" S
8 _; c) m4 G3 M9 U  x8 C
;;;;;;;;;;;;;;;;;;;;;;0 m: _8 G2 S; p% ~% I2 a/ v
;; Setup Procedures ;;
( I' O8 }5 a- \  S& ?5 h;;;;;;;;;;;;;;;;;;;;;;
: X5 N6 G3 j% E5 O% r2 h
  i- x% U+ g3 ^$ J;; Initialize the display by giving the global and patch variables initial values.0 n+ U& `9 e% W* |0 Y8 J  n
;; Create num-cars of turtles if there are enough road patches for one turtle to
0 ^7 h: T: P9 h( v1 v/ m7 `2 T. j;; be created per road patch. Set up the plots.* b2 w( F9 l. F+ a+ `) H6 _
to setup5 `- H& W5 r1 k3 Z" O
  ca% F. Q( q" e, f: w+ z
  setup-globals3 _3 Q# q# H! s) ]7 F6 n8 I- r

$ ^  Y" \: k& \" ]& Y  ;; First we ask the patches to draw themselves and set up a few variables
; R( t" V' R( s5 P  setup-patches5 [1 L1 W$ D  C7 w) W- D# j
  make-current one-of intersections9 A: A; B; p; Q! A, k
  label-current$ u9 ~  W/ I  j* ]  F

+ C0 G& _( n5 ^& g, W0 Q( V+ |( b, ?  set-default-shape turtles "car"
" g" t8 C  ^6 E
: [- [7 @( b. x- ?  if (num-cars > count roads)7 A- D. c. Z! U: i- l% S
  [6 Z" y: V% C- T$ w6 v) B7 S
    user-message (word "There are too many cars for the amount of "
$ S) y* C6 H5 ~4 z1 \& k                       "road.  Either increase the amount of roads "
2 E: v$ u) _, g; ]+ C                       "by increasing the GRID-SIZE-X or "4 U9 Q. }: j  `1 w! V
                       "GRID-SIZE-Y sliders, or decrease the "
* C9 v# d( ~! n1 g4 H3 Q                       "number of cars by lowering the NUMBER slider.\n"  l' O) O& W( ~  w8 u
                       "The setup has stopped.")# A6 D$ b8 H9 L4 b  w9 f+ W
    stop
% w3 m5 o* `3 Z" U  N! G  ]8 p4 ?# U% }9 S. v, q- A

9 J9 W' E: b# E) \0 c9 f5 ]  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color1 A, \9 L" K6 B. Q
  crt num-cars7 g- Q9 D; L- z; c
  [, W# X5 N. Q# X2 X) z) R1 P0 l# |5 V
    setup-cars
3 Y: U4 o5 `* e    set-car-color
0 ?! t: J/ S4 ^5 ^/ i    record-data3 i. H/ P( C: R0 C3 \' |! O
  ]- [9 X3 I# V* L, y; b7 ~
  Y1 l6 p3 O% y1 t7 D
  ;; give the turtles an initial speed4 f% h4 J+ U: Y
  ask turtles [ set-car-speed ]
2 Q1 E+ X2 Y/ k, f  f# G- ]6 a. r' \6 C; m. c& j, `* j9 U9 S1 E
  reset-ticks
$ u# \' Z6 K* nend
7 g; K: F0 k6 f* z/ a. {
4 J/ G2 Y5 u0 o$ `1 G6 Q1 d;; Initialize the global variables to appropriate values
. L$ M3 e, `+ m  ?to setup-globals
! J) E* m: ?9 ]* P  set current-light nobody ;; just for now, since there are no lights yet* E( ^3 I8 t# W, c6 m
  set phase 00 t5 {' \0 ~* X" f3 r2 [' v& x
  set num-cars-stopped 0
% B; j6 q* t8 e" h* Y  set grid-x-inc world-width / grid-size-x5 i. w0 e: Z! V/ S; S8 X
  set grid-y-inc world-height / grid-size-y. K9 }) C7 e: o7 S: A
1 q6 L# K! `5 Z% e1 K
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
( x+ m; o0 i; U2 q" ^  set acceleration 0.0997 A( a1 v3 P  w
end! J4 X2 B; a: W, `. o
: b! l; _/ c5 e. z+ q- C& o* L2 i
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,. p0 j% a; b! P8 o
;; and initialize the traffic lights to one setting
: g# \- F! ^1 t; {* H, @to setup-patches3 @; z' z. n+ O( p/ q( u
  ;; initialize the patch-owned variables and color the patches to a base-color
) y: K# R1 z, E  o* d5 m  ask patches8 j- ^! y& _# h* E
  [/ [1 R' ?' m. Z6 W0 B0 r, I# `
    set intersection? false
- `  o/ \& ~0 M    set auto? false
9 _4 h+ N" o  [6 ~5 N5 S& p    set green-light-up? true* V5 Q$ v) O& `6 H+ _
    set my-row -1+ ]" e5 H7 {# {. z2 j/ b
    set my-column -1
; I% t) n% t. O$ p; e4 v# B' M    set my-phase -1$ N* r  C, Z2 s% K% s: z5 ^8 U0 v1 D
    set pcolor brown + 3
: L& _. s- W; b  ]8 ^1 O# J. R7 P& X: C! T

" W' ?- a5 j2 D9 }  ;; initialize the global variables that hold patch agentsets- f* c  [1 r# I8 G, _1 d' Q0 n
  set roads patches with* j' M6 a! ?* b4 d: o) o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or; U2 h/ s" {0 z5 P9 M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: T2 @+ }9 i$ }+ E$ l% F  set intersections roads with* ]1 n0 T2 E: y, |
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
4 P2 o0 G( }# u* ~% I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 h1 H2 z8 ^1 L0 Z4 x; C7 {; r) \2 ~9 W' ^: P( x
  ask roads [ set pcolor white ]
! F% l, i" F, [5 K6 Z$ i: X  V    setup-intersections4 w9 \' F  i, [6 U; P5 z
end* B" A/ [( h; h6 K
其中定义道路的句子,如下所示,是什么意思啊?/ G8 @% @3 s8 x7 x& S1 v1 v2 Q
set roads patches with
( B- W2 r! M$ D) M- |* T, v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or; X: s4 [6 {* A9 V, p0 n2 K/ T
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 G( U6 Z1 h  f( r4 }; N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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