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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 r, M; J8 i. q+ ^
netlogo自带的social science--traffic grid这一例子当中,
6 b- I* S9 ~6 ~) o2 }' N- hglobals
2 M5 w& m" G  v[+ s$ u! ~# V6 K. V
  grid-x-inc               ;; the amount of patches in between two roads in the x direction; _1 ^3 N& U( S% U7 M" ?
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
- G& o& `  O, }. ]  acceleration             ;; the constant that controls how much a car speeds up or slows down by if: r: t; [6 M$ o2 Q
                           ;; it is to accelerate or decelerate1 n+ z( X- b) W
  phase                    ;; keeps track of the phase
) {3 R' r4 [, G+ s" `( f7 h6 Y3 A  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure) s, K; K! j% D- k
  current-light            ;; the currently selected light
* t: h  p8 f, H
  e7 p, p" g0 F' k3 b* T, o  ;; patch agentsets
6 J" ~! ~- H9 B3 x3 q' ^1 M4 K  intersections ;; agentset containing the patches that are intersections
6 u9 P( M: ?6 V! ]3 H( G  roads         ;; agentset containing the patches that are roads1 K. x# X; s& t7 J+ Y; R2 y
]
5 x; {+ g9 M- e: Q; f6 M8 Y, R  g; Y# G7 S' G/ t/ a
turtles-own, W5 d& E: O: B
[! x* @7 b* |; Q) P
  speed     ;; the speed of the turtle
* k7 r0 V& I* q1 l- s8 t3 ^( P9 p  up-car?   ;; true if the turtle moves downwards and false if it moves to the right6 [. _! }5 l6 J* F
  wait-time ;; the amount of time since the last time a turtle has moved
' S  L" {7 M+ j: U/ Q- h6 {]* o) b* M0 r' e' w3 r1 r% p

+ t9 @! ]) \1 E+ E- |/ |patches-own& x% }" w/ z, ]- e4 X* |" f8 K
[
5 S- P) x& Q& L# b4 R  intersection?   ;; true if the patch is at the intersection of two roads
  t# m6 Y' I6 [3 r1 X; r& x; `4 W  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.! a% n& x* |- q$ Z! s" ?% o
                  ;; false for a non-intersection patches.
8 A: w' m% p0 }2 G0 [8 o% b7 B  my-row          ;; the row of the intersection counting from the upper left corner of the; w7 J0 l7 S" ]; |8 y
                  ;; world.  -1 for non-intersection patches.0 W+ i- W3 y" Y4 j
  my-column       ;; the column of the intersection counting from the upper left corner of the  v- X) J9 E, q; |
                  ;; world.  -1 for non-intersection patches.
/ Z! [$ b5 _" q! @  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.9 z4 b. J  j; G! c5 F
  auto?           ;; whether or not this intersection will switch automatically.
4 g& T) n' a% E: r' N6 P. u! d1 P4 `                  ;; false for non-intersection patches., q4 x1 `  C) Q4 r3 V2 x
]9 U, O3 f: d# k4 I5 m" ]
! {* w' M7 R. h/ N: ~6 z
3 {! x0 d8 E. n& [- [* ?
;;;;;;;;;;;;;;;;;;;;;;8 r7 [& |8 H/ |# h7 S- z
;; Setup Procedures ;;2 ^- c* L) y5 u
;;;;;;;;;;;;;;;;;;;;;;
, m) |8 |; H4 Z4 F$ t! E
9 U1 r) i4 t( v# g4 B  r# u;; Initialize the display by giving the global and patch variables initial values.# e; ~  `" o6 g7 i, f( H0 `  D
;; Create num-cars of turtles if there are enough road patches for one turtle to$ Y2 b/ s, l2 ]; m
;; be created per road patch. Set up the plots.
- ^- q5 @4 |( u' B. ]" lto setup8 b% s4 D. _+ D! H
  ca, a7 V. p1 t$ s9 g8 P2 t, l
  setup-globals
) w, h% y: c- Z- g% a# I. L  |& y3 _3 u1 ~
  ;; First we ask the patches to draw themselves and set up a few variables" _- T" Y- ?1 `3 S2 U) c: Z* A* m
  setup-patches
! I, E. v' H% I7 n  make-current one-of intersections% h( c9 r& z0 c: p( ~# _4 a5 S! A
  label-current
. A6 k, S( G! i
4 x, n4 W, }9 z( O- V  set-default-shape turtles "car"9 X$ \# @1 J  a6 g' }, L0 E

' O: `$ ~! u4 h7 o2 S  if (num-cars > count roads)
1 ^; f( r5 f( n+ O# B0 L# m  [
$ d2 n8 f( Q6 C% Z& i2 d    user-message (word "There are too many cars for the amount of "
5 C* m$ t: p' |' L, R0 W) R# B                       "road.  Either increase the amount of roads ". y3 |" Z  W/ g$ q- b
                       "by increasing the GRID-SIZE-X or "
: @& n6 S1 ?" p$ X1 u. u                       "GRID-SIZE-Y sliders, or decrease the "0 O" H( L8 C  n) `$ h9 ^$ X# k
                       "number of cars by lowering the NUMBER slider.\n"* P) s9 q; q$ H) z# S; O; V+ s
                       "The setup has stopped.")
0 g& o2 w! Z2 n+ B    stop
" P4 D. q4 v) K5 A+ I6 i% `  ]$ t' ~* b: l# Z# O- x

4 w8 i7 u! p% {) Q! Q  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color* G: U' ?& o* M
  crt num-cars1 M! P2 p( Z; E! K& m/ q
  [; [' b* d+ v: s& a6 u; N0 u1 W
    setup-cars: C# W7 a9 s; x) c
    set-car-color
6 g: Z, t1 o- l' E$ j9 o' n    record-data3 d; z& M) Y9 k& H' `0 L- z* c0 B8 Y) k
  ]
2 z7 e( d' P: A2 Y: ~% k) U* |- u' l5 m
  ;; give the turtles an initial speed
6 j' t. z( D; v$ V2 `, x  ask turtles [ set-car-speed ]7 G4 j% Z2 Y" W

6 T: S2 M2 i; {' l. V# m2 v' G( G  reset-ticks
$ ]6 W& \) h) m' Aend
  S2 y. j( e# S6 f) X. z9 y) M/ g/ e6 x  s0 R' p% U/ u
;; Initialize the global variables to appropriate values
+ B. |5 i; N. q! T7 Lto setup-globals5 f# X, H, ?) O0 H! g
  set current-light nobody ;; just for now, since there are no lights yet+ O. ^& R! @7 H2 x8 E
  set phase 00 Q4 p3 Q. |9 }# y; c
  set num-cars-stopped 0% n: G  g& c( P! \
  set grid-x-inc world-width / grid-size-x
: U- r# I) e: |& Y/ T3 S8 a  set grid-y-inc world-height / grid-size-y
- F/ @! `- u$ R# o) @( z: q1 r8 U
% @  n( X+ u8 t5 C  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary4 _& `0 W. |0 T+ |4 P
  set acceleration 0.099
; S* n+ U! }$ S6 v3 jend* o' `" B  z+ e7 e$ S

# z- Q/ m) Y2 l;; Make the patches have appropriate colors, set up the roads and intersections agentsets,' M2 y4 |% X8 y2 X1 M/ n  r
;; and initialize the traffic lights to one setting$ Z4 |% K" j+ l: `
to setup-patches3 s' U. d( b4 J. k/ g$ v. @3 d5 `
  ;; initialize the patch-owned variables and color the patches to a base-color) m2 s4 B/ D: G, P5 z
  ask patches
$ M% m9 t# T5 {- `+ Y  [0 E7 O) q# \9 i! U5 b+ L
    set intersection? false* i7 Z4 h0 k2 E( `3 i5 A3 ?( _
    set auto? false
# b$ w9 H" z2 [4 d: L; L8 Y: A    set green-light-up? true% m' w! p; v& L( a; x) S
    set my-row -1
1 K  t$ m# y( M9 a$ a. X    set my-column -1( v1 |% f- }2 g# T
    set my-phase -1
7 }  x# k' I' l- M3 w# B+ L    set pcolor brown + 3$ B1 S1 \. K) Q* d. H$ `! x; ?6 O
  ]$ j9 E; N1 h; w6 d9 r" y4 L
5 a. n6 u4 a3 k1 u
  ;; initialize the global variables that hold patch agentsets. P& P8 @; ]' C1 s8 {4 B
  set roads patches with
8 p# p# G. S* s4 f( F6 v% s5 w    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 s5 Y. k( z1 k    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  u9 P, a# q! Z: P$ O  C' \! W  ~
  set intersections roads with
( a2 ^! B* \" L7 W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
3 N# }! O+ y' C$ R/ K) d- B3 ]8 s8 b    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 c$ B$ k' J. n! u* K  G3 k! n% m$ G$ G# a/ ]
  ask roads [ set pcolor white ]
, O4 b: ]! R9 I    setup-intersections
7 u/ E1 e8 G7 S, x5 h8 }5 ^end
+ W4 B9 q9 |0 `. K" \其中定义道路的句子,如下所示,是什么意思啊?, e% U' \! t4 v7 t* d  S
set roads patches with, f) ?- M% `3 B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  I$ `# n6 p- i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ u/ [1 {" i( X
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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