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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。& g; j$ k5 p$ p6 z
netlogo自带的social science--traffic grid这一例子当中,2 d; _2 |8 j2 B$ }' p
globals
! |  x$ b0 f" W[
5 l. k1 E1 U$ \  grid-x-inc               ;; the amount of patches in between two roads in the x direction
4 ^( h" _5 X+ C* u/ e7 M' i  grid-y-inc               ;; the amount of patches in between two roads in the y direction
. K1 B: W1 z# h5 u/ M% W& I  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
* R( z6 F* R2 g! Z5 w/ V                           ;; it is to accelerate or decelerate4 x/ t4 U; N1 A$ `4 c3 y8 }
  phase                    ;; keeps track of the phase3 c4 |! C) d; N; i% ?  f
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
& u/ z4 D% h& O1 ?" S  current-light            ;; the currently selected light
2 Y( w# ?5 K, I2 ^, A# E  k/ T: d% `5 l
  ;; patch agentsets, U+ d7 R% D7 f0 C! {% h4 s; u
  intersections ;; agentset containing the patches that are intersections, r0 H7 e4 Q8 B) I" Q! A# S
  roads         ;; agentset containing the patches that are roads
' ?3 d/ v- D' P) p. ~9 K]  e. H+ d  K. T1 N9 \" Z: O

" D' I& Q& Z& c& w$ Uturtles-own
3 X* r; X$ F$ M; e[
5 ?* d- E: @' e' c# R) s. I2 U9 Q  speed     ;; the speed of the turtle
, y( D/ ]/ V. K. O: f3 b  up-car?   ;; true if the turtle moves downwards and false if it moves to the right6 f% t6 k8 f3 I! D7 _; q
  wait-time ;; the amount of time since the last time a turtle has moved  |3 r! D/ m0 @: m  n" n
]% i6 m' \/ h1 `5 I
! a3 ^& s& B- }+ k& \0 a
patches-own0 H/ J6 t" g  j
[, z: S1 m2 T( m* ?
  intersection?   ;; true if the patch is at the intersection of two roads
+ N  P, O* g9 r! w4 P3 J( G8 h4 v  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.7 D5 ]* u3 w' g" x$ V1 T$ P
                  ;; false for a non-intersection patches.9 J5 S- A. o' C: e2 J
  my-row          ;; the row of the intersection counting from the upper left corner of the! p( t5 |8 s( \/ o" O: f
                  ;; world.  -1 for non-intersection patches.
% d  t) F, v+ a. ]0 X  my-column       ;; the column of the intersection counting from the upper left corner of the
- Z' l# R  W$ T3 I6 `: A5 g3 g                  ;; world.  -1 for non-intersection patches.
4 |: F+ I; {/ I3 p) v  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.1 _/ |  n2 x7 W) `8 P
  auto?           ;; whether or not this intersection will switch automatically.& {2 M, i; q( U, F0 ~) d* C3 b! p3 B. P* i
                  ;; false for non-intersection patches./ l) c  w$ h0 W1 Q
]
+ Y4 {# D% |+ K$ B& p
; f( c$ {5 `+ R
& e) L9 Y' D. U! ]2 Y;;;;;;;;;;;;;;;;;;;;;;
+ s* {9 f. o  T/ z;; Setup Procedures ;;
7 R# s9 S* [  [4 p5 I;;;;;;;;;;;;;;;;;;;;;;- E1 V% T+ E+ t* G7 v% \  i/ r( z

' o- Y3 S8 U/ Y7 P3 |, t;; Initialize the display by giving the global and patch variables initial values.* h! |8 ^) s) G/ G0 k% W. r8 K
;; Create num-cars of turtles if there are enough road patches for one turtle to& [% \6 U0 D+ i, }$ {' ?' }5 N+ t
;; be created per road patch. Set up the plots.
7 J- ?( |. L, i; z/ X+ E, {$ Ito setup
/ L. n/ @1 u# V1 Q4 k  ca
( ]3 A9 D# w/ X% s3 w/ c5 y  setup-globals
  |- m3 u, P( f) x: t7 |
8 m% s  O1 ?5 T% G: d* ]  R  ;; First we ask the patches to draw themselves and set up a few variables! }2 J8 a1 Y/ S  v
  setup-patches
, \1 b; Z7 g1 [8 [( j9 A  make-current one-of intersections
* y7 F* v5 M- ]: G& X" o  label-current
% [5 Z1 U) }. g( @' D- j/ Z# W$ o1 ~) W. ^
  set-default-shape turtles "car"5 [' D% A* s' W

( b! ~; E4 f# X  if (num-cars > count roads)
% _4 b7 l4 B8 N. v& ?  [4 {" d0 U$ m7 J' i7 p% l$ f
    user-message (word "There are too many cars for the amount of "
2 M7 a7 h% K4 z9 Q2 Z                       "road.  Either increase the amount of roads "
' W+ w5 N4 {1 K% q                       "by increasing the GRID-SIZE-X or "
9 x4 `4 C) o$ r- r3 R2 P6 f                       "GRID-SIZE-Y sliders, or decrease the "4 j0 U8 H6 a* m2 m, y
                       "number of cars by lowering the NUMBER slider.\n"
* ?- l5 y( G9 R0 h8 a5 a                       "The setup has stopped.")$ @) q' o( e! b  W6 k
    stop
2 r# m# X  h5 m$ H  ]
5 ?; @$ }$ N9 O. I' {. ?% y) K6 k. X& X9 E( U6 H% {
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color6 @* t5 o, }. L# p# Q/ I$ ]
  crt num-cars
6 f3 W  j7 F% s) h4 s  [  U: C1 x  f4 e' E3 T8 `8 E
    setup-cars
5 b$ X. I0 K6 r' R/ _, g0 X9 n    set-car-color) y( ~5 n# ~* K- m8 b% j! C( \/ q
    record-data
4 [& D9 ?: t; m" z" e; h/ u  ]! j  E9 E# @5 n. \6 W; E4 K' ?
/ P; m4 F0 ?! E5 e; m- n
  ;; give the turtles an initial speed
- \* p9 W. F4 y! \# M  ask turtles [ set-car-speed ]
# e' |- p- c2 ^
4 r6 L3 ~" c4 `* P# s( `* k  reset-ticks
  y7 w: S' ]# z9 O' z$ t+ aend5 P2 \" q7 O) }% S  v- D
+ x( j" W3 M2 O) |. h% @# S
;; Initialize the global variables to appropriate values: r6 O5 a5 K& E! F% Z
to setup-globals
/ s$ g& W/ q: y! F" S2 P5 c. b  set current-light nobody ;; just for now, since there are no lights yet
& f8 L: U( D! D; a; j; c  set phase 0; M9 T8 ~: u+ t9 h* s! C* v- d
  set num-cars-stopped 0
* r" E- h0 A1 e) D6 u. q3 m$ n5 B5 r  set grid-x-inc world-width / grid-size-x* o( g1 Z, V, z1 U
  set grid-y-inc world-height / grid-size-y
/ S& b0 C8 @* h- R7 A' M
# o8 _/ l$ h5 s4 S  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
& U7 T( w+ U* i/ m8 }! Z; t7 o% K  set acceleration 0.099  i& e0 w0 U( M1 [4 x
end6 o; \. M: s2 K  M* W

! o4 q$ y$ J! o/ g;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
4 p* N4 O' [1 Y8 y. |;; and initialize the traffic lights to one setting
  u1 F! P" R+ t" o; Y' Mto setup-patches6 [: f/ J2 T# _1 L% d
  ;; initialize the patch-owned variables and color the patches to a base-color
% o' G4 b8 |8 F+ ]; N5 G* @1 Z; x3 G' b  ask patches$ F1 T  g! R- ~  @# @$ f5 m
  [( r/ Y+ V  i+ d. h% m' O& V5 c
    set intersection? false
& G" X- Y% Z  ^+ n' s    set auto? false
6 B. L8 U% j- K7 B    set green-light-up? true
: F% `+ i5 U' m3 U) Y: i' z    set my-row -18 m" i& V' d) a2 _$ p, `
    set my-column -1
9 [$ e$ ^: Z: j( |  c    set my-phase -1$ P! L- L) z3 c: {9 l7 S
    set pcolor brown + 31 p% u" f7 @9 Y) X1 L( J' p  F
  ]
0 d. B* X0 p! I+ k" A9 F- {  P
  ;; initialize the global variables that hold patch agentsets
8 o7 t8 Y8 R, O; K4 z  set roads patches with
; ?4 y  s" f7 e, Q, M. p. m    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( E' }9 g: O# v1 v. L' s( M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 J0 |" b: l2 n+ p, o$ f: C4 g  set intersections roads with
( i( t: a6 F/ Q$ n! ~' C, j% X    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and- E% J- `4 E, E, J5 w
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 n! L3 D$ r* H2 p
3 t/ |) a3 U' ?& d  ask roads [ set pcolor white ]
( f' D* ~. I* K: w    setup-intersections
; \+ l$ r( g  h' m- b0 G) I* Bend
* B! r, W( L  t. ~* L+ t7 m% d其中定义道路的句子,如下所示,是什么意思啊?& U! y1 H+ X8 ^- m% G7 q
set roads patches with9 ^( L1 ^9 M3 Y4 N) Y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 h4 X. O, n; W; g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ |4 L# \+ Q: E# n- U- I* x8 z7 Z: U
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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