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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。5 W5 _; }5 z& f+ U* h! i7 X$ f
netlogo自带的social science--traffic grid这一例子当中,5 C5 a* y, ~5 b8 E4 A
globals
  g5 B7 \! Z. W[4 J# V, e0 ^: q
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
2 \( X0 \! r' p. M+ w8 I  grid-y-inc               ;; the amount of patches in between two roads in the y direction
) n& H. m: q( n  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
6 Q- O5 M; Q3 {9 Z' [4 N                           ;; it is to accelerate or decelerate$ [2 R7 _* p3 j! C9 g
  phase                    ;; keeps track of the phase
9 Y! T( Z, u9 G  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
# \& R7 I! P7 j' }  current-light            ;; the currently selected light, J/ h. _# F. k2 ?

% D: {  @  [3 L, z: G' x  ;; patch agentsets
8 A% e2 ~8 z" q% X  intersections ;; agentset containing the patches that are intersections
) T/ u+ _# u9 l4 w; e  u' x  roads         ;; agentset containing the patches that are roads: ]' Z# b8 ?( a" x! t6 z1 y$ h- U
]# n" F2 @6 `! @2 |0 m5 M% \- c
/ @. h+ q1 P. J
turtles-own
/ W0 ]1 `1 j9 V# R' K[% k4 w0 z& F8 T: u! P+ o
  speed     ;; the speed of the turtle
! G9 V  }1 \, e" s: t7 ?; r% V' S  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
: \- {/ G% L" L$ d  wait-time ;; the amount of time since the last time a turtle has moved4 {3 L" N" t7 Y! D( S
]
  F( `8 w  p0 n4 d% c" {2 k3 K
5 R( A" y5 X9 e: z' Mpatches-own& n; E' ^3 G9 f" M5 i
[
, A# w$ R4 I+ N) @5 a0 s4 Q  intersection?   ;; true if the patch is at the intersection of two roads
& e; B. s: @( r- {; Q  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.3 c9 L! r4 t7 e& K8 N3 K
                  ;; false for a non-intersection patches.- t* k& @- a9 c% u1 k% z- {
  my-row          ;; the row of the intersection counting from the upper left corner of the
2 ]2 j- P( V9 i2 `$ }                  ;; world.  -1 for non-intersection patches.
# R/ b: C- [0 V* e9 k9 C  my-column       ;; the column of the intersection counting from the upper left corner of the. L3 a1 x8 `6 I0 _0 e+ U. x5 w
                  ;; world.  -1 for non-intersection patches.! R, u2 w1 j2 y& Q/ l
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.& T$ Z2 x& C2 K2 Y! {0 N' h: E
  auto?           ;; whether or not this intersection will switch automatically.
/ n( a% \1 [  J# V! e) T                  ;; false for non-intersection patches.
4 d  Z' c& l4 O: `. a$ S9 x' ?, U]+ U9 G- A6 l, _4 T; _" S

9 p% t! d0 g  A) ]
, U" m; c8 U# J; h+ U0 O;;;;;;;;;;;;;;;;;;;;;;! A) ]; R9 \0 a* c- i' Y2 j; ]) [
;; Setup Procedures ;;
5 Q9 m2 M8 S/ Y0 X;;;;;;;;;;;;;;;;;;;;;;: Y" f& \% h8 d. Z: |

3 L" j- f, Q; _;; Initialize the display by giving the global and patch variables initial values.
3 Y+ k. m5 A' y, F;; Create num-cars of turtles if there are enough road patches for one turtle to
3 K4 p+ ^) A4 \  x9 t;; be created per road patch. Set up the plots." c1 q, k" x9 t; i; l) L9 |
to setup9 g2 D. C% k3 Z
  ca
$ ]+ v  S5 Y& F! ?  setup-globals
6 C8 O+ `. B3 ~1 L3 A" {) I0 _8 A  h; g. z/ j- _, ^$ K+ R
  ;; First we ask the patches to draw themselves and set up a few variables3 l8 V0 {) z7 b* i% z* r) [
  setup-patches
# h3 V- l( K/ z0 I9 ]8 D  make-current one-of intersections
( L8 k3 x. ~5 [. Y( v4 Y  label-current
  k1 i2 O3 _- k) [% P  N  y$ H, L  b' K. l
  set-default-shape turtles "car"0 R6 B3 J7 B. X0 _3 U; `

& c+ B% p% \$ f2 @  if (num-cars > count roads)
. K/ g* b" D3 }  [! N4 R9 K+ [( x5 g) o1 a4 ]
    user-message (word "There are too many cars for the amount of "+ H" h/ N  q& M
                       "road.  Either increase the amount of roads ": `* @; H- b9 c1 v: n
                       "by increasing the GRID-SIZE-X or "3 D5 d$ u9 _* {4 ~$ B9 O
                       "GRID-SIZE-Y sliders, or decrease the "
5 y' t' i( x0 h3 y# m) M0 y                       "number of cars by lowering the NUMBER slider.\n"
6 U1 [& {4 g& e                       "The setup has stopped.")' T) H! J& R: C% ^! G! N
    stop, N3 i* c1 J! [0 W! e7 i  x
  ]% A  O  k/ n; N9 d
* a9 T! Y3 {) q* w6 u% X8 J* a
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
0 x3 W! L) @; Y6 r: |. k1 V  crt num-cars3 _1 e. J1 L* J; n
  [
8 Q3 ?# {( K9 ^    setup-cars
) }8 {, V& U7 D; M) ]& M" i7 N- d    set-car-color
) G5 Z4 f" A' _: Q2 d7 z    record-data
% P  ^- P# c6 X/ m) Z  ]% e+ `0 R; F" ]5 W1 W
' Q' P/ A. W6 H/ n+ `
  ;; give the turtles an initial speed: t9 y3 \. f  Y' Z' _6 q- p. O
  ask turtles [ set-car-speed ]
) }+ Z+ `5 e$ ~; d( h0 U2 W, M: a; q# P$ N
  reset-ticks% n7 u' Y, D- U3 s- D4 K. x2 o& {
end6 x9 r5 h. U7 L& z6 |5 W4 s- r/ R$ j
. Z9 T+ S$ a- w
;; Initialize the global variables to appropriate values
! |) x* V7 M; m. d& ]- {* `8 Eto setup-globals0 R4 _8 j* ?4 e1 {4 F, M
  set current-light nobody ;; just for now, since there are no lights yet- r% L: W! w3 A) w1 q! [
  set phase 0
3 f$ B1 }: N; i$ P+ t  set num-cars-stopped 0' }! f; Q+ `& U  }3 B
  set grid-x-inc world-width / grid-size-x
- t8 ]+ I9 b4 _8 v9 L2 f  set grid-y-inc world-height / grid-size-y% n* T3 T0 r/ {) ?+ G' U
6 D/ u& v0 n( D3 j# ]
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary3 V) P% \2 b# ]. Y
  set acceleration 0.099: E( v  x. ~& P/ l
end
- I2 Q' P% l$ R) g; D, [" P& j6 J) o0 p
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# R; Y" i0 p1 X5 @;; and initialize the traffic lights to one setting
& M" l1 p# b: d" m( @* M5 jto setup-patches
5 q- C- n8 J- i4 a5 }  ;; initialize the patch-owned variables and color the patches to a base-color
9 G& ]* _2 h2 |: B$ _9 B6 d- a  K  ask patches
  ^; k% u. C* v1 a( ~% M1 k$ k  [
5 A* q  C  ?, O4 G" N' E; y    set intersection? false
% n1 o* X$ D( s. `1 [" Z, y# U    set auto? false; c# T; S. }* Q& }
    set green-light-up? true
! `4 V$ l  z2 q& ^, A3 c    set my-row -17 B4 Y1 b. R1 I
    set my-column -16 H8 H( G) c& b2 L5 u
    set my-phase -1
; t# R& ]. V# q3 L: j5 Y: p& K    set pcolor brown + 31 q0 P6 j  V3 v$ M4 B# o2 }$ a
  ]
0 Q6 L' P. d+ _, ~5 f  B2 k2 E( g; {: U) h1 Z. X
  ;; initialize the global variables that hold patch agentsets
/ z' @& {, {0 Q$ X# C& `  set roads patches with% @' K) b" Y$ L: [- D( q/ d
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 z( Y3 T# |7 n) r
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) N+ D, e- C$ Y/ d3 C
  set intersections roads with$ h" Y+ D% k0 ?  T+ F4 ]! r
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
4 v4 ^# y$ G! x/ }1 s" z7 N  d, W    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, J; v9 A% ?4 A- ]' m) y/ t& Z& ?1 P8 v
  ask roads [ set pcolor white ]  y- Q. A6 `0 @2 P" |1 `, M/ E
    setup-intersections
- f3 ^$ c7 v  W/ H. ~% R+ Q& W0 L- W' Aend
1 r4 f2 v( u$ [( i其中定义道路的句子,如下所示,是什么意思啊?$ d* ^' M1 D* E* R( A) [% q% b" S+ a
set roads patches with
' o4 V$ b. ?9 w' S; v" e' g    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ E4 e# V+ G2 a    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 a. L+ u8 |5 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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