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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。
+ y. J/ m- k1 V5 k( Fnetlogo自带的social science--traffic grid这一例子当中,
7 f' n# u2 D* N  [globals
  R+ b8 Q' |+ G! A* W9 r5 D[
7 c9 \  X9 o$ }4 ^0 v% \  grid-x-inc               ;; the amount of patches in between two roads in the x direction* V4 \* ]( U* \) e# q: b5 U
  grid-y-inc               ;; the amount of patches in between two roads in the y direction  d. j$ d8 E& `2 t7 W8 e. ~
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if. f  n$ |& u4 M9 Q0 R3 g' J
                           ;; it is to accelerate or decelerate
8 W7 N$ w8 t& J, s, @5 E  phase                    ;; keeps track of the phase
2 t8 X' U5 J+ S6 ]+ w0 L* S! _  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure: i3 v/ J% b) ^$ e' ]  m3 o% l7 y
  current-light            ;; the currently selected light, L; y3 i- ~. `9 L+ p$ w( C' J6 w" d

2 x( J/ n7 h7 D( R7 Q  ;; patch agentsets, D, }: }; Y( C7 {
  intersections ;; agentset containing the patches that are intersections) A. a3 y1 [. ^! ~' d2 p
  roads         ;; agentset containing the patches that are roads: J5 `. R1 ]9 p7 z" S0 i
]
  l; v% a- [7 R. ~. K  }
* h9 H* H- y  k9 m3 e& ?turtles-own
5 B1 J8 W) V" |/ J; m[% F6 u/ L- j- t" c" `" E1 R+ l
  speed     ;; the speed of the turtle
- M4 V0 W, f: V3 P  up-car?   ;; true if the turtle moves downwards and false if it moves to the right2 I& k$ P0 A( s, V1 D
  wait-time ;; the amount of time since the last time a turtle has moved/ H, f  d+ f) Z; h
]2 C/ b: {+ b8 G6 ^

, |: u9 D' K" A' u4 k- y. ]patches-own+ B4 F: ?& G5 H/ i
[
0 I* S. x$ o' W# N: ^! B6 S  intersection?   ;; true if the patch is at the intersection of two roads
" p' a& x" ~7 s  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
5 O6 g% h3 Y, a6 }                  ;; false for a non-intersection patches.
4 `' ]% G! o; [# r. M  my-row          ;; the row of the intersection counting from the upper left corner of the
' V+ ^" n' M: v: D                  ;; world.  -1 for non-intersection patches.
1 j" z+ ]& p9 i% M, M  my-column       ;; the column of the intersection counting from the upper left corner of the- L* r& [% }* A
                  ;; world.  -1 for non-intersection patches.
9 a2 r  a0 c& z: S+ n( _  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.7 R5 j& \; x5 @' s  K
  auto?           ;; whether or not this intersection will switch automatically.: R0 T* j( K+ O  p; y
                  ;; false for non-intersection patches.$ h8 u; S1 X' j( [3 u7 e2 j. u
]
: s. f# {# ?5 A: M" ?' D; a& e: Y1 y; t8 }$ |  K; k" Z! K

( ?- b6 m' u  E( V5 n;;;;;;;;;;;;;;;;;;;;;;
8 q+ \9 M3 l8 r* A9 Y: W;; Setup Procedures ;;3 h  z9 O3 P0 Z9 U
;;;;;;;;;;;;;;;;;;;;;;6 b2 v7 K0 I6 ~3 h2 H8 |, U1 z
  k1 ]9 V/ t+ L( |. l
;; Initialize the display by giving the global and patch variables initial values.
; m# t4 D" m( A# c. E0 z: T1 r;; Create num-cars of turtles if there are enough road patches for one turtle to4 ?$ N# s) P+ K! F, V0 C
;; be created per road patch. Set up the plots.* h: O( H; t+ v9 M! @
to setup4 i, T  C" ]; C3 `
  ca
4 {" M- O( R) R4 q% @, j, M  setup-globals
* s9 C, p1 w( ?$ A* ]  z& q% Q2 @! J
  ;; First we ask the patches to draw themselves and set up a few variables& B0 u5 [1 t$ K
  setup-patches
7 O6 G8 X. C7 i3 S; \3 \  make-current one-of intersections6 b0 q0 l7 C. D- a5 f
  label-current6 ^) f* b' m% N% ?
5 p: E8 V- b) q- O+ V
  set-default-shape turtles "car"* A5 n9 [- ~0 O+ m6 o( D! ]
8 R$ G7 r* e) G2 W+ u, e
  if (num-cars > count roads)/ I/ G' r0 y$ ]- }, U
  [
$ _1 r* g5 T2 I  Z5 ?# ]3 I2 E# F    user-message (word "There are too many cars for the amount of "5 p, K) V; _1 G9 u  k, g, _; x
                       "road.  Either increase the amount of roads "
0 I9 J8 v- [. S. ?7 t, a% T                       "by increasing the GRID-SIZE-X or "1 E! r4 j' m: n* L/ A- v: S% s
                       "GRID-SIZE-Y sliders, or decrease the ", j: x: j- m: |* X3 L6 x
                       "number of cars by lowering the NUMBER slider.\n"( Y3 u9 N: t- u. C: n' n7 v. r
                       "The setup has stopped.")
( |1 c0 S* s1 ~8 X7 M8 g0 t    stop. d, N* u$ }5 Q6 F
  ]1 S0 w3 I+ A) b& m" m

2 N. \! }& k6 n+ B  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color) u- H8 w9 b/ T( P
  crt num-cars
5 y& U7 G; }& D+ }  [
7 e6 _% e$ a/ _: s0 {    setup-cars
! r; m' T' z4 L0 ?# |2 Y    set-car-color$ h! _. r- X) t9 s. w' ?
    record-data7 N4 v/ d- q+ h" v" a
  ]2 t  L2 e6 |# J3 {/ L2 _! b

' D1 m( Y1 f0 _2 T1 n. ?3 D  ;; give the turtles an initial speed+ o* _% e0 |) C: Z: S' F
  ask turtles [ set-car-speed ]
) b% {* I- |% ]( ~7 c: P$ l$ {2 e1 M5 m' f( j1 d
  reset-ticks& V& \. v/ h0 }/ q' P% U
end$ {" D+ M( B/ a; [. P
7 e( i! W& d) K1 u
;; Initialize the global variables to appropriate values
8 m) E' s8 T4 L5 ?, Y9 Cto setup-globals
, B/ i5 ~! G) r; j+ f  {4 {  set current-light nobody ;; just for now, since there are no lights yet6 {3 Q6 q. `' {& E+ Y' M3 @
  set phase 0- R; D1 |+ r0 Q; D% y) x# a
  set num-cars-stopped 0( a* q7 j( d* D, ?( h$ E  B+ x" r
  set grid-x-inc world-width / grid-size-x
) M; O" y& T" K+ `( c" [  set grid-y-inc world-height / grid-size-y
4 X2 M! ~' U; h, l+ R/ z& S: S: i4 U! r; L1 S# R
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary3 t3 _# _- G  {) c" t
  set acceleration 0.099/ D( f3 s/ w( q& [: s
end  `+ s5 X/ B- T8 f, d) W% W

* o" z7 Q1 R. h8 M- Z;; Make the patches have appropriate colors, set up the roads and intersections agentsets,9 I# p: k8 Z0 L7 l: M! k
;; and initialize the traffic lights to one setting- s* ^, V* h' Y" x
to setup-patches; \# ?. b! g% |
  ;; initialize the patch-owned variables and color the patches to a base-color
0 }7 S, F, `2 z% Q( ^. U% Q5 }: o  ask patches5 A1 \& q! }+ m) c% t, J8 j9 g5 t2 w
  [' E. b  ^. ?, a8 N9 r6 B2 b
    set intersection? false/ u1 @5 J' V2 ^
    set auto? false
; p! J% @& n8 w& U7 I1 @0 F    set green-light-up? true- |, _8 `7 J, K2 o+ J8 c
    set my-row -1% D! d( k: I/ N8 T  p1 \0 m
    set my-column -1
3 p3 Q. w& V4 Y- S& T+ e    set my-phase -1, L5 Z/ `! h9 i6 e* q: ^; ^3 A3 ^
    set pcolor brown + 3
8 z, Z8 K/ ^# M8 V! i' Q  ]5 l7 j8 N* {* e- z) v& \* Q
8 K' H$ e; \) r! [+ |$ }
  ;; initialize the global variables that hold patch agentsets3 v2 N3 S0 ^) J* M0 Y
  set roads patches with
3 z, _) c/ g& N/ e7 E( S# H    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 q* i  }# V: w+ k1 ?9 |% Q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], {. B' X+ M- w/ \, ^0 K" W" y# {1 z
  set intersections roads with; r( |. E) [9 Q$ |# c! u/ w
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
3 @/ p  u3 I) Z6 F1 K    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" I# H8 R. C$ F) o
1 y/ ~- H+ W" T0 J! e/ F& _( f
  ask roads [ set pcolor white ]
) O9 `) M5 \: Y2 [# o) j# W    setup-intersections
- R! _4 k9 F" z( W3 Q$ i: A. \end5 }' w6 m% W+ l3 w* e! C
其中定义道路的句子,如下所示,是什么意思啊?
4 a, R; X& `0 K# y set roads patches with
. Z+ g* X5 ]& P3 D6 o! ~    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 W2 G/ ]8 o1 J% }6 v9 C    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: u. b6 l5 A" f  d$ H: W6 W
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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