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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。: ?2 H9 A7 g2 C2 K: H' T/ g2 _% ^
netlogo自带的social science--traffic grid这一例子当中,& t6 F4 ~8 R5 {' L3 F  ]( I% c, |
globals; e: e+ V( P2 l& h4 l
[7 ^$ ]! Z$ a0 g5 u
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
) H1 I, a% Y3 d/ W  grid-y-inc               ;; the amount of patches in between two roads in the y direction
! ?1 I( L+ I% w3 x3 l4 x  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
& a4 K( I0 N& K4 G" ?- f0 b                           ;; it is to accelerate or decelerate" W/ J5 s% U5 C" b
  phase                    ;; keeps track of the phase
% Q, W$ y, |2 n  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
  d, ]: h6 F2 i! i. l2 E+ I4 }  current-light            ;; the currently selected light  p4 ?" \% S! q0 x! R) t, u. W
4 G8 `% `0 n% {; E6 P+ d
  ;; patch agentsets
- E9 t* V' R) Y  intersections ;; agentset containing the patches that are intersections5 e/ Q  k& e4 ~
  roads         ;; agentset containing the patches that are roads
% b8 P+ u+ k8 M]
6 h) \. x+ d: I: d3 k) S9 g, A5 D0 X1 o% X: K
turtles-own9 b+ G4 B9 m+ @- \, Z' _# T
[4 j+ d; ]* l. `
  speed     ;; the speed of the turtle
! T+ _( v, Z  d3 ^; F: O  up-car?   ;; true if the turtle moves downwards and false if it moves to the right. N% o0 i5 g5 O5 w* J, P& q0 T/ _
  wait-time ;; the amount of time since the last time a turtle has moved) K$ F& i% e4 T/ F2 @2 B6 j; O  C
]
9 ]$ K3 _# V6 S& D; ^2 p; y1 g. O1 I* u- B% R. R
patches-own4 U+ D4 ]- S8 e5 J3 \2 ~$ n4 l
[$ w+ t/ h9 I  _5 d7 X
  intersection?   ;; true if the patch is at the intersection of two roads9 z' m! @8 d. `$ x3 {$ p
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.0 ?) [: u9 v1 K7 Q- H# U" S: R
                  ;; false for a non-intersection patches.3 G% V- j' ?8 d3 m% b
  my-row          ;; the row of the intersection counting from the upper left corner of the* R& c3 H" S7 T3 N" w  I/ ]
                  ;; world.  -1 for non-intersection patches.. i( B$ W/ l( M3 c' Y
  my-column       ;; the column of the intersection counting from the upper left corner of the
9 [- N' z4 {0 r# N                  ;; world.  -1 for non-intersection patches.) J6 C! y# P0 p
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches." Z4 D4 @& O1 ?4 }* o3 c5 M" d
  auto?           ;; whether or not this intersection will switch automatically.' |  s4 |, F- Q1 A# L- N# ^
                  ;; false for non-intersection patches.
8 x2 k' D/ t! F/ k$ I2 I" i]
% _# ^- D+ z% R# M+ p9 D1 Z! a. {8 t2 H" K, _

( j# j) D* t6 |7 D! @2 ~;;;;;;;;;;;;;;;;;;;;;;
0 y6 G$ ~% C  Q4 B2 ^;; Setup Procedures ;;
! q. S2 y' w) \1 v- J;;;;;;;;;;;;;;;;;;;;;;
2 S2 o* w/ o9 \+ x1 e5 Q1 Y5 T9 a3 v% l- T
;; Initialize the display by giving the global and patch variables initial values.; y7 d  ~/ k# n# y: l2 \
;; Create num-cars of turtles if there are enough road patches for one turtle to
0 `/ q# Y6 l, s  }) G2 V# m;; be created per road patch. Set up the plots.4 E7 h6 y( ]0 Q3 a
to setup
6 [7 R  O/ F: L  ca: E; P7 O8 v; m6 v
  setup-globals0 r. A: S' x( x- G) V
  I% O! ?' ~+ ?+ T
  ;; First we ask the patches to draw themselves and set up a few variables
- @/ n* Z, K2 e  setup-patches
. c  P! ~1 Y' J4 \  make-current one-of intersections  {' S% m$ m" f6 J; f" _* s+ Q
  label-current
5 ]( l9 `9 ~- k. F  t$ O) [) a
* N4 {# E/ ~5 w) |' v3 L: u; i, o  set-default-shape turtles "car"
- s* b  }; V3 u& Q! F
: |8 l6 `6 j6 c  m1 J' w# C  if (num-cars > count roads)
# r& E5 E5 Z& a3 A7 V0 @! J- k  [
2 G2 ^, ~7 T7 w- K    user-message (word "There are too many cars for the amount of "
1 E! I, p6 B! V; Q8 v8 q4 M                       "road.  Either increase the amount of roads "& F# o9 ?. ^, }" R) M& v. l7 F  R
                       "by increasing the GRID-SIZE-X or "
. \& ^: z( E4 L% k$ }: O3 O                       "GRID-SIZE-Y sliders, or decrease the ", B0 Q( a: ^3 `* q& ?6 j4 k
                       "number of cars by lowering the NUMBER slider.\n"
  C6 ^& O% m9 o' o                       "The setup has stopped.")
7 r$ T% p0 q( `$ Q9 b    stop
( C/ \3 q: |# y' e3 n9 \# Z  ]/ Y! o" m3 r" c9 e, L5 r5 ~/ v( `
! F6 V9 P1 G" N2 Y! ]- P; j
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color6 p" ^3 d/ z/ n" N+ z4 w, @. `
  crt num-cars
- f- t7 _: F$ _! P: j- T, T  [
3 d* o& \/ n' T  C! R- a    setup-cars
! M+ O4 i5 U4 t1 }2 X    set-car-color, M5 x% b, C: E! x* ]1 P4 P
    record-data
% y1 [* g# Q& ^6 M8 s/ J+ |  ]
/ @/ _2 c1 z& \4 U( j  G, ?$ B! A; _1 g% v) H
  ;; give the turtles an initial speed
6 n# b1 R# k  K" V, L  ask turtles [ set-car-speed ]7 o& v- b2 v; F- X8 Z- T. G) u

: N- U$ @7 a1 E& ?  reset-ticks
8 b2 U( A5 n" I* f- N8 ]1 ~end( H& L' R! ], Y) c" j
: \$ d. u: G6 a3 U. q& u
;; Initialize the global variables to appropriate values
0 c9 s! n$ z3 Lto setup-globals, O6 t* i2 f! Z2 ^6 F. q
  set current-light nobody ;; just for now, since there are no lights yet
) }  Q: I, w' W! `, ]! N/ v  set phase 0
. A, [$ a9 o# s  [2 [  set num-cars-stopped 0
$ W3 l, O$ V  c6 F  set grid-x-inc world-width / grid-size-x2 c: X; `  ^! n6 z2 c
  set grid-y-inc world-height / grid-size-y/ s6 L( C5 x; o, G

4 a0 E8 M4 q$ D9 j" S' ~9 w1 H. y  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
* |# ]5 D5 Y( g  set acceleration 0.099
  P' ~- x+ y1 h' |end
7 }& }4 M! @6 d- k4 X& k, w6 _  {1 v5 y4 e; e& X
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# k* M- h+ m( K# y' A! N- O5 X;; and initialize the traffic lights to one setting3 `$ f& S* d' R+ d7 E0 w9 }" _
to setup-patches
. M" j2 e. y# n. J1 Y- T0 x  ;; initialize the patch-owned variables and color the patches to a base-color) d2 e. O/ ]& o' B
  ask patches$ K1 T3 \9 `* R( Y, M1 V+ @
  [
  v3 S) a! E3 Q& q* W8 N6 |    set intersection? false7 K0 k/ O1 T# ~& M8 `* l  w  f
    set auto? false
! i+ ^" h, v8 f9 w( Q0 f. `4 n    set green-light-up? true
) W. X! Y4 F8 T5 l: m, b. M    set my-row -1
0 a* |4 {, w% Z, P" j/ S5 |5 i    set my-column -18 p# S4 Z3 O- c- k# z4 h2 `- |
    set my-phase -1# W5 C$ I0 {% ]; R8 n
    set pcolor brown + 3! H% ~) |! d( v: H; B% W
  ]
8 |' X" I$ \! g$ x
/ G( n* n$ h* j3 \( E  ;; initialize the global variables that hold patch agentsets
& z8 I1 v& z' @: w- x9 J1 p% d' D  set roads patches with
# N8 F4 n1 }: j( r3 |1 l! x; z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* R/ \' k/ N. `4 n. d$ Z1 ~2 h
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  f  y  |' w0 `" v- \
  set intersections roads with* l, X. p( X/ D* Q7 B( L0 g0 V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and, l$ ^( I1 p, s7 G! w, p
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* Y7 B, f+ p$ ?0 U; r) z' v6 l2 Y
2 I) p1 {) ~  k! _2 u* `# W
  ask roads [ set pcolor white ]" O2 B7 ^- \) n
    setup-intersections
& O" P' z- _8 x) N5 vend
3 @. n, D! G* t3 W  p* N3 G其中定义道路的句子,如下所示,是什么意思啊?
- ?, o+ N: |* I0 F3 l1 f$ w set roads patches with0 U  I4 r& U8 b; t4 o: Y8 Q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 F; s* W6 Q) M3 X    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) K6 e/ l4 y' p. A4 `7 K7 q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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