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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。8 f2 L- E; q) {2 \
netlogo自带的social science--traffic grid这一例子当中,
9 d" o- Y3 t' U" a. O' J* N" ?globals9 I1 W& V/ h- X9 f# k) Z
[
# h" i; J& _3 M  grid-x-inc               ;; the amount of patches in between two roads in the x direction
2 e% ~- E3 M# {1 V. F5 m# o  grid-y-inc               ;; the amount of patches in between two roads in the y direction
- D4 N9 s: q  A1 V  acceleration             ;; the constant that controls how much a car speeds up or slows down by if* m0 Z$ G/ F* y
                           ;; it is to accelerate or decelerate# `- @- f* t- G  f1 e7 c! s
  phase                    ;; keeps track of the phase
6 D) Z8 ~& Q6 v' c% p2 @- X  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
; l' K5 J: b9 R. A% v+ m3 n1 T  current-light            ;; the currently selected light
% h  D  n9 h0 ]3 a1 o$ G/ T) R0 z
/ K& r" C  V) I4 v; y4 ]  ;; patch agentsets
. F% b# R. P$ `  y9 r/ M0 [  intersections ;; agentset containing the patches that are intersections
! T& R  W4 k( S0 I: v& x# l  roads         ;; agentset containing the patches that are roads
: B6 K; D+ D  s6 R]
0 l" E$ {6 e% i6 Q; S) ~7 j: O+ Y
turtles-own
9 c( Z7 X/ o1 ^& w- Q4 ^[, |  k! \( }+ Y! M/ _
  speed     ;; the speed of the turtle: u8 a# B! z! p+ d" K6 N
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right* D+ D0 Y* f1 s
  wait-time ;; the amount of time since the last time a turtle has moved
4 z- r" k7 W/ h/ e9 p. ^) o]
, k9 r8 ^% c* M7 U$ p' ]; d6 f0 ~8 ]; h5 L' K: \1 b! t8 v
patches-own
0 H3 \& h7 P, \& U# `[
6 }" Q+ V! y3 A4 V9 C- Z: o  intersection?   ;; true if the patch is at the intersection of two roads
) w) z  G- T# N3 }( w+ ?* W* I  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
6 k/ O) Z: u" y* y                  ;; false for a non-intersection patches.8 l2 d1 J5 C  Y5 |) U2 z7 X
  my-row          ;; the row of the intersection counting from the upper left corner of the
, g* S: l! G9 {, e, r$ T" {                  ;; world.  -1 for non-intersection patches.
" o3 s4 g& n7 k" S4 C- R" F3 J  `  my-column       ;; the column of the intersection counting from the upper left corner of the  d" N2 K9 e) u. X0 F3 @: C
                  ;; world.  -1 for non-intersection patches.* u3 h' {2 N6 e- a
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.' B- e9 i% |( h3 Q- ^
  auto?           ;; whether or not this intersection will switch automatically.& c1 a8 m: b2 Z. H
                  ;; false for non-intersection patches.$ I7 Z7 o2 T1 `9 Z# ?5 I4 q
]
9 b1 W/ h, k# L  A0 S7 P7 ^% |( W1 H/ h: [4 j
- V. x  a& ^2 |0 T9 I/ X
;;;;;;;;;;;;;;;;;;;;;;
) v0 V8 o2 e% _+ U5 \7 q) w5 r1 w;; Setup Procedures ;;
' L) `' v, X# N: D;;;;;;;;;;;;;;;;;;;;;;0 B- X9 i" \0 ^9 m$ {
! f, {& R" }4 F0 {
;; Initialize the display by giving the global and patch variables initial values.8 _) F7 N8 X7 \) J
;; Create num-cars of turtles if there are enough road patches for one turtle to( v- Y$ ~0 D, X' z
;; be created per road patch. Set up the plots.
2 r6 G) W2 R( s* D8 \, t1 d* qto setup+ n; S7 {3 I3 S; E
  ca5 l+ s" L3 ^% x  f1 I" @, J
  setup-globals
. w% K% V! z1 |# g
. g2 h& @: d' m1 ~' |8 c% r  ;; First we ask the patches to draw themselves and set up a few variables
, H: J( u  o; M5 v5 q% i  setup-patches' [& g+ |- Q1 g. h8 ~
  make-current one-of intersections
0 Z% z/ ~; i7 z& F- J  label-current
# B9 g" [5 Q7 [
  l+ e; I* g1 f  set-default-shape turtles "car"
% B0 @. i( l. a7 e, z- u9 c( o7 O( }( |2 g, z9 I
  if (num-cars > count roads)( P2 p$ Z' R: r. |
  [4 @5 n% U, l3 [% H+ v
    user-message (word "There are too many cars for the amount of "
8 Y0 p/ |4 }; l! M/ U3 o                       "road.  Either increase the amount of roads ", k6 S3 A6 P* \  [
                       "by increasing the GRID-SIZE-X or "
+ c1 A; O+ @- ]& R                       "GRID-SIZE-Y sliders, or decrease the "
3 E2 E1 s0 Y% P                       "number of cars by lowering the NUMBER slider.\n"/ W* E3 n5 r8 z1 a* K' y4 x
                       "The setup has stopped.")6 O  M1 [2 T$ ]9 v" u: p* z
    stop+ p" U+ h  L' C8 k. u8 U$ v" b) g
  ], @/ |) S/ |4 ^0 X; J
1 F( O+ |# P- O: G, z: [& D
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 t2 G! q4 i5 v0 ^( K. G9 ^2 }4 ~
  crt num-cars2 I0 Y8 E) a" ]$ \
  [* X5 z. o# }1 y& R2 _
    setup-cars
4 D% I& t4 K. O& @2 D) ^$ }    set-car-color9 A2 N5 T: W4 ~7 u, Z6 }& z
    record-data+ ]& k3 k; Z& `' Q4 b$ z' l- f
  ]
' f/ J4 }4 J9 A" ~. q. H
: W/ m: q/ l! o; x# y' e# a  ;; give the turtles an initial speed2 i- @4 t+ I* L( |6 ?$ t
  ask turtles [ set-car-speed ]& j$ p6 y# w5 ~! U5 p

* Y# a, ?; l; j/ s. N  reset-ticks+ L5 y5 i3 O: B6 }$ F7 l3 R8 Z) y
end& \, ~9 r, t3 W  E7 P
+ j( y, B( _" A7 J  b1 `
;; Initialize the global variables to appropriate values
; f& J- }( z1 _6 d7 q6 l% _to setup-globals
4 X5 |' Z/ ^* a6 j7 E  set current-light nobody ;; just for now, since there are no lights yet0 t2 D$ W8 X8 v7 |- W5 w) q( `
  set phase 0
7 [' l/ ^' j* W% H/ A! Q5 @" o  set num-cars-stopped 0
  f4 G( H( H+ @* ]1 [2 w  a  set grid-x-inc world-width / grid-size-x
% n8 i5 S1 x$ w3 D; r( ]  set grid-y-inc world-height / grid-size-y
' a- w3 m6 w+ \6 g2 m
, l) _, v; A$ w" [+ f5 F7 D3 P  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
3 H8 O# O- `, t7 }. q( P3 U  set acceleration 0.0992 t* c! ?9 ^! H
end  v% g2 ]- j0 A6 p! J) n( \1 b' i
& r8 L0 a! W5 }% ~! t
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
6 W, w* |+ c8 Z' w) G1 N;; and initialize the traffic lights to one setting
% S2 U8 B1 P8 _7 o, v  Uto setup-patches. b6 n* T; b1 ~0 w
  ;; initialize the patch-owned variables and color the patches to a base-color
' O% g; a  H: d8 K* ~  c  ask patches. T& t' q# G' I) I& `! \
  [. E) V2 g* t2 W6 C3 @( b
    set intersection? false
) p( @- w- V. G& o, c. f    set auto? false" U8 W: D! A. q' t/ j, k' S4 |
    set green-light-up? true9 M( T' T: x( w3 v
    set my-row -1
- i7 @4 j3 a6 b3 b8 @7 n; p    set my-column -1
1 C+ k% f2 X8 \& d) A; I" w+ h    set my-phase -1
& r9 a8 [$ K  D. ~    set pcolor brown + 3
3 @! v/ h" n1 j% \: {% p  ]
) H, W1 u& Q8 ]) B& n1 O" D
6 D1 P* H1 V2 s& N) L& X  ;; initialize the global variables that hold patch agentsets2 p4 c# F" X- a  b  L2 K. g
  set roads patches with
: w& P" [, L. I# C* k' B    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 a! E6 M7 A3 T4 z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 H" Q9 Q. w( [8 j" Z: I3 z& F
  set intersections roads with  U) _' a0 h; W; k/ A
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
  ^* T9 W3 M& K* }) i7 `8 S    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: n3 I: O, U4 B  H) {8 l

; R, n$ j2 b1 g& Q# }# s% V( n  ask roads [ set pcolor white ]  h' o4 E  e8 o$ @/ t
    setup-intersections
# _( u$ I) ~- I; d# l) U( mend  H5 D" p! w4 [8 E, r& v. y" B
其中定义道路的句子,如下所示,是什么意思啊?5 [6 i2 f2 s' f9 ]
set roads patches with
% e% q5 w7 @8 Z9 F* O- ^  A+ y4 w, {/ R    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% c2 M- |' P: A6 J
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], R6 t& O! `! v+ Y5 u. i- 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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