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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。) F$ u8 F& U5 B$ j! F- N/ A3 D+ H
netlogo自带的social science--traffic grid这一例子当中,! z8 m6 f% e8 Q  D. ~/ [: q6 r, u
globals9 O+ U8 `6 G$ m+ v. u
[' e5 x) J+ ^( \1 W
  grid-x-inc               ;; the amount of patches in between two roads in the x direction) H; L  S5 @& n- ~7 E' _
  grid-y-inc               ;; the amount of patches in between two roads in the y direction9 L* m' y" L5 e- r* K
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
  @! L: ?$ `) Z- F                           ;; it is to accelerate or decelerate5 s3 @! s  d  z6 }
  phase                    ;; keeps track of the phase
7 [" \( W; I" P# U  j  m+ \  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure3 A- H+ @- D* Z/ T: Q$ }" [. n7 {
  current-light            ;; the currently selected light5 B3 o# i6 ~" W/ `* X
/ J$ k2 _: f/ t/ L% e2 d5 y$ r9 w+ Y
  ;; patch agentsets
% q5 {$ ?1 j; ^. S$ b  intersections ;; agentset containing the patches that are intersections) m, Y4 Y! e  a. L2 v8 W
  roads         ;; agentset containing the patches that are roads$ W0 S8 c& `& Q; Z
]9 x7 Y7 z, k5 v  a8 z

  @) {; ~) A( y2 `7 l& w" aturtles-own4 q' @. I% I( N
[: U' a+ w4 _/ ~$ t
  speed     ;; the speed of the turtle7 r0 r# I3 F+ u* p2 U6 w4 _
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
% y3 p1 a' Q: ~  wait-time ;; the amount of time since the last time a turtle has moved/ |! B( g& J5 W) _* E, X; j
]
* q0 ^0 E8 I: E4 ^: x" }
8 @$ h0 |- z' ~% lpatches-own- g6 @6 Q% G0 q9 A8 D! g! f* K
[
3 P* j8 A- m5 A  ]: I5 h1 v  intersection?   ;; true if the patch is at the intersection of two roads
" I3 k3 Q3 [  ^# o8 y7 |; r+ Z  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.7 D& ?3 H: I; K- j/ U
                  ;; false for a non-intersection patches.9 v6 B4 a: p: S: y
  my-row          ;; the row of the intersection counting from the upper left corner of the
, u8 o' [$ L1 T) R. ]' P  a                  ;; world.  -1 for non-intersection patches.1 M4 @2 A) w- u( H9 F7 ^! u5 `4 d
  my-column       ;; the column of the intersection counting from the upper left corner of the
% |4 |! ~" T5 n* W! ^7 C' T6 g) a0 W) e                  ;; world.  -1 for non-intersection patches., b5 M$ }2 z; F, X" o$ |5 P
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
3 E% K7 ]% g! W7 w0 b  auto?           ;; whether or not this intersection will switch automatically.4 j% S3 s. L* x# V
                  ;; false for non-intersection patches.
7 Z/ I9 V: e6 {4 `$ N6 G]
( e3 U/ [9 s9 T# t8 e# U$ C# D8 M6 ~+ y/ T7 g: H' l: G2 f
# A3 V. `4 U+ v' m
;;;;;;;;;;;;;;;;;;;;;;& G1 k) m& ]3 N2 H
;; Setup Procedures ;;
+ n6 k, U' I5 K: y/ ]% ^;;;;;;;;;;;;;;;;;;;;;;4 Z: ]" l2 M6 M9 R+ q1 k
! m  t1 d& J& v2 ?
;; Initialize the display by giving the global and patch variables initial values.& k. ]/ _6 H  j' |
;; Create num-cars of turtles if there are enough road patches for one turtle to
2 Q. U' f, c$ F4 ]# p8 a* O) z;; be created per road patch. Set up the plots.
0 D8 @# }1 l$ Z1 Kto setup
# l6 m/ c, q; i2 o  ca0 s' ]; L, l$ j7 R9 r0 F
  setup-globals! K( N) e& G6 w; `

, a3 A9 ^# V) `* d  ;; First we ask the patches to draw themselves and set up a few variables, \4 @' c* u- R) b: i
  setup-patches
$ k' u7 q6 f2 \0 R8 J  make-current one-of intersections
$ ~% s# N/ F# S1 J6 ~& K( h# D  label-current$ q- [+ S4 g% s, n# u% b6 t* c. X

) u. @/ e3 B8 ?0 w; P; i3 B4 Y* i  set-default-shape turtles "car", d/ w2 s8 g, ~8 B# F1 ^

; c: A) N2 s. n0 p7 Z3 G# U) Y* U  if (num-cars > count roads)
+ @$ }2 t" T% R6 q0 T9 g  [
0 Y1 P3 N& W9 f    user-message (word "There are too many cars for the amount of "
9 a! n8 x# n, E4 i) [) `3 [                       "road.  Either increase the amount of roads "8 v5 ~) |  G! E6 y
                       "by increasing the GRID-SIZE-X or "6 a5 H2 c6 A4 v# T; ]
                       "GRID-SIZE-Y sliders, or decrease the "
$ }) P9 {* E1 {7 `9 k3 ^                       "number of cars by lowering the NUMBER slider.\n"
6 l2 t. s" s" Y/ ]4 J                       "The setup has stopped.")
! _( P) e: z# ^8 g    stop$ ?0 d& C4 _9 b) B
  ]1 a& n; t$ j* V7 Y& J5 b: s
! n$ M. Q- w5 ?$ b- `
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
# W! q% o- r* r& t1 s  crt num-cars8 z0 y1 u; J1 `6 Z4 K
  [9 F! ^; S7 l# S! p1 z/ {
    setup-cars& o2 U- h3 E' \3 k
    set-car-color# M# b3 I4 }$ @9 n8 M
    record-data
7 R& t% F+ |8 l7 }3 y+ Y% A  ]# v. `! ^6 S" r0 t$ |

5 i+ A, B6 M" A" |  ;; give the turtles an initial speed, {1 f8 E4 X; e1 N
  ask turtles [ set-car-speed ]
: K1 h7 F  b; n$ r
3 T+ d, x4 {7 ]( U3 Y/ [- x: H1 d  reset-ticks- r3 v1 H. k+ C: c3 e
end9 H2 Z% G9 ]; ^" Y9 H

0 b& n/ t! v( k/ C# I- D& `;; Initialize the global variables to appropriate values8 ~6 ^, m1 G# ^9 O4 J
to setup-globals$ E) g. x$ I' z3 K& D
  set current-light nobody ;; just for now, since there are no lights yet8 D+ {' z0 _) ~8 {
  set phase 0
# @' @6 |; S- }; A! |/ H  set num-cars-stopped 0( f* Y, `& |1 d$ |! F
  set grid-x-inc world-width / grid-size-x' J. V" B/ X: i5 H" t7 [6 x* M0 X
  set grid-y-inc world-height / grid-size-y, S- G5 @9 m6 ^

5 K7 @. |* n4 K$ c! I0 Y( Q1 J  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
  ]) I5 V% M0 r5 ?6 @, z. r7 r9 [  set acceleration 0.099" s. g6 C( x7 g9 s% O! \9 O
end3 Q) z& |' I0 f. k2 m1 r
. f( v4 ?3 W+ `
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
8 g, X5 W: |  Y) D. C2 {! B) G8 Z;; and initialize the traffic lights to one setting+ K' o$ o1 I2 U% z6 w, W- V4 }
to setup-patches
' F( a+ C# U. |# `; Y+ y7 ^  ;; initialize the patch-owned variables and color the patches to a base-color
1 s* t) d) y2 G6 f! }$ d/ j  ask patches; F  h% D! w, Y; v
  [* k' }3 C; {; {) D4 s% A' ]% k
    set intersection? false: [% h1 d1 F$ X% `6 ?" ]$ T) G8 S
    set auto? false7 N$ E+ a, g: E+ ]- o& P% L
    set green-light-up? true
7 I2 K1 E: `: u    set my-row -1# U& Y& W3 g5 N  d" l4 T
    set my-column -1
; b* H# Y2 @* R- V4 t. V* a    set my-phase -1
2 c4 A5 Y  {0 J8 f; N    set pcolor brown + 38 H# _0 F( M$ L- b) i, a' i
  ]
$ m. S  Q9 h0 E4 ^) D8 q8 l. d# X9 \
  ;; initialize the global variables that hold patch agentsets( r% i. j; a/ J: ^# B. k% J
  set roads patches with
* E! \/ U; L, ?4 u8 h9 B    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or# ?- M$ Z* M8 Y* F
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; C+ S! ?& c- m: @! l! U3 G  set intersections roads with
) C0 f' c! w( f' C+ D+ Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
+ V# ?8 H$ l3 }8 g% G2 @    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 x! R) [& b3 d

8 s) r' Q) q9 V$ ?  ask roads [ set pcolor white ]
4 l1 C( r5 J  w6 L% [    setup-intersections
/ L3 M5 m6 L2 lend& b9 r/ x; z& j7 _" o3 J. U9 G
其中定义道路的句子,如下所示,是什么意思啊?+ x( `0 V9 ]# M+ U* W
set roads patches with% c+ U) }9 a/ y5 P" C* E9 [" s
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ V, |, }/ s2 v! _9 ?9 R  g
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 F3 B5 k7 Y9 n; K0 @- o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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