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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 \4 k$ m: g3 K0 \3 R# o
netlogo自带的social science--traffic grid这一例子当中,
: U7 n8 w! Q5 n1 u( M( R7 e* _- ?8 ?3 Pglobals( }# y* A  ]% }7 \5 }1 d6 _
[$ n" Z+ V1 D3 W( {! _
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
, a1 z& ]2 p( @$ i6 @+ I  grid-y-inc               ;; the amount of patches in between two roads in the y direction- Z1 u/ b9 a( Z2 C$ Z& _- n
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
& e% _; M6 t, [9 q/ ]) E% H                           ;; it is to accelerate or decelerate
* o/ g* Q- \* S& Y  phase                    ;; keeps track of the phase
$ f$ V. P1 `& b6 I4 q- I- S8 i1 J  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
" o) g2 D9 ^. w  current-light            ;; the currently selected light. K8 a- |, C* l
; K3 ^  A, E: o. d2 C, Z
  ;; patch agentsets
0 y* m, [/ i$ F- c7 b; E0 \  intersections ;; agentset containing the patches that are intersections
4 E& \+ w) j  d3 u  G  roads         ;; agentset containing the patches that are roads
0 [, Z+ W, u  c! l]
& [! _$ h6 O  j: @3 {# x- ^& W' s
/ i" l* m- V+ uturtles-own
+ ^' J% k, Q9 O. z5 w/ M, l$ L[$ m+ u, z$ m5 H' s  ]/ Q  @1 O* t
  speed     ;; the speed of the turtle
% V1 s& ^9 h3 x) w* p  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
) E" ~2 i+ {# u9 a. @  wait-time ;; the amount of time since the last time a turtle has moved
+ m% B5 R# y) ^- c7 Z/ ]]
. k9 T, B. @& U: M+ J4 }5 j0 o' w& [5 r" m# Z  E8 X; O9 Z
patches-own
$ M1 ]  Y5 q3 w6 o[* w& O' w% T( r3 X3 t' p! M. B1 D1 D4 a
  intersection?   ;; true if the patch is at the intersection of two roads
0 @6 _, G6 T- R  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.  O7 f$ S4 {  H1 w
                  ;; false for a non-intersection patches.% u4 t% A8 m6 C6 y- o7 R. F% K
  my-row          ;; the row of the intersection counting from the upper left corner of the
4 j2 K3 R) r# i0 [5 F                  ;; world.  -1 for non-intersection patches.
3 }. q+ H& L  p4 {2 q4 m  my-column       ;; the column of the intersection counting from the upper left corner of the! S- V4 O4 C. P! R$ c4 @; N! y
                  ;; world.  -1 for non-intersection patches.' F4 ?7 U/ v2 ?6 }. e, m
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches./ [  G8 E# j7 @. a
  auto?           ;; whether or not this intersection will switch automatically.2 R3 P0 u; B! h$ Y% x* P
                  ;; false for non-intersection patches.' ?. W0 c% R9 d) ~3 @
]
; z4 b% m2 P: k) \+ |3 G( N+ z- z8 I/ M: D1 k: x+ y" F

) r& z. A* `/ z, g) C' Z;;;;;;;;;;;;;;;;;;;;;;" Z% c) g/ a# z# d
;; Setup Procedures ;;
( V( k1 i; X1 A  [, ^) H' O  r+ l;;;;;;;;;;;;;;;;;;;;;;
1 d' v5 Y9 b. W- t/ @' b! y  X$ B. M1 R8 h+ h6 E" q  f
;; Initialize the display by giving the global and patch variables initial values.
/ L/ v/ {# {) X, \# H4 J. `;; Create num-cars of turtles if there are enough road patches for one turtle to4 U2 B) Y8 m9 j1 o; {
;; be created per road patch. Set up the plots.
8 V$ t9 U2 s5 I2 Y. bto setup9 h( H9 M" C1 J4 ~8 G- h! Q; c" e
  ca
& F3 x0 w6 K+ {) ^' z  setup-globals
! t& s! h9 T1 I& O9 k3 ^  c5 R8 F0 P' x* b! s, r, M) x
  ;; First we ask the patches to draw themselves and set up a few variables2 B9 Y. j1 N% Z' i# u( o6 J
  setup-patches" J' L( B- L; D  b* r5 m5 }
  make-current one-of intersections
6 i: e- d( v9 |% _& h" G; t  label-current0 g- {% M: \+ \* y' }
; {/ t. m: f/ P4 v/ ?5 q* l  u
  set-default-shape turtles "car"9 |0 h( t3 _' J% f8 E; d0 b4 a5 X

1 p/ Q+ C8 Q8 U  if (num-cars > count roads)5 r, m6 I; u- S7 O
  [: N8 Y4 Z* G6 c6 e8 y/ `+ f& H3 g; A
    user-message (word "There are too many cars for the amount of ". w& c" v3 a; ]" G0 U6 d7 o
                       "road.  Either increase the amount of roads "& `( F. X3 q/ o+ d7 z, D
                       "by increasing the GRID-SIZE-X or "8 X6 w/ p8 w: b& k+ P9 t
                       "GRID-SIZE-Y sliders, or decrease the "( W" S5 a. s0 j1 Q8 U5 x7 O
                       "number of cars by lowering the NUMBER slider.\n"' X! q5 H2 |# P% E) J3 p0 p. \" D
                       "The setup has stopped.")' R. O$ c: v; s- j- S7 }, c, Z
    stop
# g8 r$ i# M. ?' S1 g  ]
4 S) n: L, G/ p5 d5 x% p
8 c+ h! i: T8 C) @! ]5 Y8 [  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color5 c9 N+ ^" q0 f# [8 M
  crt num-cars) q0 U  ~- z/ m
  [
$ y6 n3 r2 S5 p8 m$ m* |    setup-cars
! `) Q% P8 ]* I- h: q    set-car-color3 f- h# M/ _/ U* \% w4 j$ _
    record-data9 Y- h" n* A) O
  ]
6 `, n9 s8 ?$ [3 S8 s
; j3 g( w$ K# O8 t8 M  ;; give the turtles an initial speed$ {" W$ x8 F9 ?4 Y) v: ^
  ask turtles [ set-car-speed ]! T% G* L9 M: g! o9 ]+ b& d0 I
3 l4 x$ E% N; s# W2 F7 j
  reset-ticks/ Q6 Y8 @, n8 N" b
end- N, p, U1 _! S

" s7 V, Z) S! c: d* Y8 P;; Initialize the global variables to appropriate values
7 x7 u, W" w+ O+ R2 B$ p' b+ m: l* lto setup-globals
' ^! ^) X! ]- d% j  set current-light nobody ;; just for now, since there are no lights yet% `" Y1 \! e3 c* e1 h7 t
  set phase 0
& F: p8 A% \0 G; ]" z/ ~  a/ z  set num-cars-stopped 07 s- i. v$ m) z6 |1 S( O
  set grid-x-inc world-width / grid-size-x$ b8 H. T' r  I' F2 S8 w! \- `
  set grid-y-inc world-height / grid-size-y
/ X( A- v4 b. P+ m' `
$ ~& m' @5 d- i9 u/ H* R2 ^. x  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
1 i3 `1 P) V2 H: H3 c1 Y/ r  set acceleration 0.099
: u9 K) L2 w# m8 C' Eend
% z7 o+ m/ N6 }' R0 |& U" r* M( i7 F  m5 q
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
- x4 d* A# q% N% {;; and initialize the traffic lights to one setting( e0 \, t5 r1 S" H) D, D
to setup-patches& I( s0 o* ~& B
  ;; initialize the patch-owned variables and color the patches to a base-color' s6 Y! J5 p% c! h5 W# A1 D
  ask patches6 T- G. X# a* d) B& |
  [
: j& O) J+ r. c, C3 h3 q0 g3 h    set intersection? false
- V% Z! M7 h- U! f) K0 c    set auto? false5 y, \7 `1 T, y
    set green-light-up? true5 \  w3 w9 ~) c2 c* a" _) `* ?; Y
    set my-row -1
+ W( H3 y' o% B8 c* f% k3 V    set my-column -13 n8 M& {4 p6 S8 F+ j( R7 D
    set my-phase -1
% x+ ?, v( O9 [: G& J% P    set pcolor brown + 3" c9 G6 w$ ~- w9 f
  ]3 e# ?4 Q7 s1 h0 N* c! f. h
9 S% {/ F( o( g6 _
  ;; initialize the global variables that hold patch agentsets, b- @. ?0 o, |0 _
  set roads patches with
# Y9 _9 o1 Z/ R; y/ k, T/ s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: b9 ~8 O% Q* M) L( r8 V5 W    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 m$ o8 k% P& V  set intersections roads with' A* ~* f+ ]/ c" U( Q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and8 S. M: Z/ T9 ~! [$ [
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" P: B! t. ?- C  @- T* w, B! I4 {+ i
' W- t0 p  c* G8 V# O, x  ask roads [ set pcolor white ]3 ]% ~: d6 K- u! z2 i. D1 b3 i
    setup-intersections2 y" a9 @1 \1 Q" h  B; a  B( v
end
, I2 L" d" e, u0 J+ h其中定义道路的句子,如下所示,是什么意思啊?& P0 M7 ]5 w- `1 G
set roads patches with
1 R$ B2 L$ u9 |9 A6 r; {  K    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 d- x0 c9 E2 m) l, P1 |
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 T, \( u2 ^8 L5 i! g: n; 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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