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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。
, w4 t$ x5 u+ C* `5 i4 Mnetlogo自带的social science--traffic grid这一例子当中,
! p  A2 d; H8 k9 r- ~% Yglobals1 V7 X- C! k0 [2 Y$ t4 H9 g* c* h
[
: N- d; \1 K' \. v8 p9 G  grid-x-inc               ;; the amount of patches in between two roads in the x direction
% ?+ O# x3 x6 a7 l  grid-y-inc               ;; the amount of patches in between two roads in the y direction
: J" J( G* ~' d& n: J! ^4 t& f  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
0 o! n& H8 p) E# N: A                           ;; it is to accelerate or decelerate
' S, t* N5 ~" d6 q! L  _& t  phase                    ;; keeps track of the phase  G7 A# U8 y* |% W
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure9 C# g$ N7 z8 T& A0 W/ S
  current-light            ;; the currently selected light8 h  ?3 O" |( t; l
* ~5 ?* u* y$ `* O
  ;; patch agentsets
) k" L# J# G6 P  intersections ;; agentset containing the patches that are intersections
% e' ]9 h& C9 ]8 i  roads         ;; agentset containing the patches that are roads. Q4 J, D; t6 D3 M6 `
], t) Q3 k4 N( o" l
( w, Z) O1 m, O4 D9 W& ?
turtles-own" S- m6 p8 N6 _3 G
[
  z- r  M" X; ]  m+ v  speed     ;; the speed of the turtle
/ S1 H8 Y% B+ S' }; Q" x  up-car?   ;; true if the turtle moves downwards and false if it moves to the right6 L- q4 [1 W$ D
  wait-time ;; the amount of time since the last time a turtle has moved
9 @# J' O8 e* A6 C& Z]% m, ]2 t: O0 l+ k

/ h6 |& o9 N3 t" Upatches-own9 x7 C4 u5 Q! E( ?5 Y
[
2 n+ P4 f) K: D. ^, v! w  intersection?   ;; true if the patch is at the intersection of two roads
/ U6 l; V- Z9 n1 f3 E  F' i  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.6 O1 m- L7 V$ H0 W+ Y
                  ;; false for a non-intersection patches.0 x9 Q$ H6 j7 U+ `( c8 w
  my-row          ;; the row of the intersection counting from the upper left corner of the
7 P% a) p) J. m                  ;; world.  -1 for non-intersection patches.# P  i+ w+ y' ^' v, a. A- A
  my-column       ;; the column of the intersection counting from the upper left corner of the
" u2 y( _+ J% b. O3 ~0 `. w                  ;; world.  -1 for non-intersection patches.' R. k0 S1 X# Q8 }* Q, q. H: ^
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
; j, I) K6 c9 X( Q2 I/ M# z  auto?           ;; whether or not this intersection will switch automatically.
% ^6 t8 z' T/ I+ r3 ]( t                  ;; false for non-intersection patches.& `1 V( I, v; O  I% W- s9 \( ^
]
9 G! \3 R  V; \. l% ?3 K- V; i
  k' z) d9 t5 s
( n# I2 ^  K7 B6 k* V;;;;;;;;;;;;;;;;;;;;;;1 d5 B" N7 s# X5 ]7 _
;; Setup Procedures ;;
% `( k+ [$ g$ j8 W7 b$ f;;;;;;;;;;;;;;;;;;;;;;
" l$ A, b6 H# U. O. u  D/ S) P
& C: S: b. y3 j' t7 Z9 J;; Initialize the display by giving the global and patch variables initial values.
) W! H! _! U- r: g+ r;; Create num-cars of turtles if there are enough road patches for one turtle to
. `6 ^- w# l! P% |1 E. [, j;; be created per road patch. Set up the plots., U$ L1 n5 @* {8 Q
to setup
4 ~2 W8 C- v2 s  ca" t2 J7 ~6 p  D, ?; S  }6 X
  setup-globals
$ P! i" m1 R0 X
1 {$ v& c2 X' V( J9 l+ L  ;; First we ask the patches to draw themselves and set up a few variables
/ n: N: L; {: W! ~7 q' }. M  setup-patches
* p( ]+ O+ V% y% h" V  make-current one-of intersections0 {  O$ i! n- A5 a
  label-current
+ U' F# y) W9 g6 F$ O' f1 S8 t* S9 o; _' e: n7 T
  set-default-shape turtles "car"
4 C) c% O7 `) C0 T; z% t4 N& f6 p( v$ g0 b5 y1 ^& ^
  if (num-cars > count roads)
* f; f* r+ d: N7 H1 L8 U) L4 \% Y  [
" ^( `- u4 {* y    user-message (word "There are too many cars for the amount of "
- t" ~7 ]2 L/ f. k# e$ p0 \! D6 ~                       "road.  Either increase the amount of roads "
) a5 |" W' i; B* O                       "by increasing the GRID-SIZE-X or "
" ^& N/ r4 |6 ]" t& g+ l4 s                       "GRID-SIZE-Y sliders, or decrease the "
" D: Z: A5 ?. [0 N' s                       "number of cars by lowering the NUMBER slider.\n"7 \. Z9 }) H6 d" R4 u0 A# R* B5 h
                       "The setup has stopped."), u. L6 @0 n, [) ^+ P' z
    stop% V  A  z7 z5 [
  ]$ v. P. T* W: T3 {+ S. D9 I! u
3 D# [4 D# ], y  P6 C* K
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
& ?8 M3 j8 T% D  n  crt num-cars
6 v+ Q5 r8 i8 B  u  [
& S$ K# H0 c" u: R    setup-cars
* l4 C* ]. C1 s* T$ Y' _    set-car-color4 h) \+ t4 j  w& O! n6 t. e
    record-data
" W9 n  a1 ^: S( V4 `# w  ]
) y% O  ?- m" S% r* L7 [% b2 f+ u. z; ?; Z, t+ p/ V
  ;; give the turtles an initial speed# c& c, h* y) z% o$ D3 S
  ask turtles [ set-car-speed ]: D9 {  u- u( N6 e: Y' n+ C( v
3 ^) H) `" x) f- B! ?, L  m! |
  reset-ticks
" ?7 m' i" H* F; w+ b2 J1 }end! m: _) v- E" x" I* c6 x
0 d6 z+ b# U$ F  j/ r  O/ @
;; Initialize the global variables to appropriate values/ x: H" R0 U# R0 i
to setup-globals
5 d/ p2 b, h4 A9 q& ?! g6 {  set current-light nobody ;; just for now, since there are no lights yet
2 p; @' r; E+ z$ _  set phase 0
& g: v& X6 j* ~# G  set num-cars-stopped 0
% M* ?/ U  Q% L# O  set grid-x-inc world-width / grid-size-x
% {9 k5 [/ D  [8 C8 M: Z, y  set grid-y-inc world-height / grid-size-y( z& s/ B: g( t
: h: Y/ K, V( @2 e
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary# j8 T, d  Q$ K+ H6 {1 x" P) C7 I
  set acceleration 0.099
: x% V6 ^  ?) I* R- D( V1 qend
" O3 R- B3 J; {9 G# u# Y2 u/ M3 Z7 l+ l& I5 j
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
- v3 P& v# \' @& [1 U# J+ f;; and initialize the traffic lights to one setting
% v) s/ {& K% S5 _( @to setup-patches' ?3 K4 L, g  \$ M2 C% y6 N
  ;; initialize the patch-owned variables and color the patches to a base-color3 U! z5 c" f' v2 X* s$ ^+ n$ ^
  ask patches' ?$ W9 d3 O) O7 M
  [9 l+ b* E% ~" g' S& ~. v5 _" \+ [( k
    set intersection? false
2 R) V1 [2 W6 w5 M, D9 Z    set auto? false
. g; ~0 n4 B+ H& m6 L1 m8 R    set green-light-up? true4 \. T5 D) f$ _0 R4 n7 c/ r, Y
    set my-row -16 e, {2 }, R6 m
    set my-column -1
. \% W" `, K- r: U8 V( E    set my-phase -1* L" W: ^) l" l) |0 R
    set pcolor brown + 3
6 c2 d; z" F4 k$ a0 Z% V/ f  ]
* ]  u  {; X+ M  B( K* p& ~2 G4 }5 n2 j! v" a, Q
  ;; initialize the global variables that hold patch agentsets0 l8 |9 z3 ]5 T# \0 h+ l% k
  set roads patches with
9 ?* J6 m: n/ w7 g' M* j    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ b/ V( B+ I- f% @    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], I! l. l4 C! {. V  j
  set intersections roads with. M4 i1 a' F4 t0 T; Q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and* L' v4 r7 g. @. F  g8 l) ]4 r
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 T. f( W' K$ F
* X3 E1 ]4 S* A+ y+ i  L5 l
  ask roads [ set pcolor white ]
, a7 N3 ]3 [; H7 z) E    setup-intersections
- t0 n+ w& _. [; `* Tend0 e# c+ A5 }* Q" l9 d6 a. Q7 l6 s
其中定义道路的句子,如下所示,是什么意思啊?
/ ?/ \/ J) ?8 r1 p; v) o set roads patches with8 b; P) u. A0 V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) o& H) ?, _; @4 f# h$ U2 o    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ ~8 [. C; a/ Z
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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