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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。& q7 l* J. T, _  u- K, L9 ~
netlogo自带的social science--traffic grid这一例子当中,% T; R8 @. e5 l( Y6 Q. o
globals
& M2 N7 t) }9 E. g% Z( F' h1 H" d[
" F6 ^# t# L# b0 R: E1 d  grid-x-inc               ;; the amount of patches in between two roads in the x direction
" z, R! `+ ]0 x2 t  grid-y-inc               ;; the amount of patches in between two roads in the y direction4 A4 h4 t( A$ Z
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
9 e- a/ b% r) d- J" ?                           ;; it is to accelerate or decelerate: i2 M, |* x; R& j9 F* S
  phase                    ;; keeps track of the phase, K4 Q+ h! f" [( c5 f
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure0 a9 R- u# K  R% h: r! T
  current-light            ;; the currently selected light
; N4 N( I; `2 U; p- |* y: u0 K, E% H: H; A
  ;; patch agentsets1 B+ k+ L7 ]/ \; i2 [
  intersections ;; agentset containing the patches that are intersections
2 x6 u7 P! j6 V5 H  t! q3 J  roads         ;; agentset containing the patches that are roads
, W, F* @5 w% b0 _9 Q& a! d7 n( x]( s; s6 W9 ]# |4 s, J

! h! }, J" W1 o, k( U6 _turtles-own  n# n7 \( D  A/ i
[# p5 Z. B/ }! H. g
  speed     ;; the speed of the turtle
5 F6 m8 e9 z) T  up-car?   ;; true if the turtle moves downwards and false if it moves to the right  D2 x+ p) m/ \+ B3 M
  wait-time ;; the amount of time since the last time a turtle has moved
4 A; k- Y! |9 F3 c+ |- m* v: n" c]5 b8 u  Y4 S% @: l! ]% [# `
  p/ {5 F4 p" I' L( s) D9 p
patches-own
1 a3 l/ `- L5 }% E' w[4 q4 f0 _! S1 s0 E- I8 W- t
  intersection?   ;; true if the patch is at the intersection of two roads: Q" z) ~+ A* z, \
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
! o7 N- l, h- ?, p                  ;; false for a non-intersection patches.
% A6 P6 f# `; v  Y3 `; J# [4 q  my-row          ;; the row of the intersection counting from the upper left corner of the
9 l+ z1 h6 ]0 t6 Y  @                  ;; world.  -1 for non-intersection patches.6 r3 g% o3 r9 d
  my-column       ;; the column of the intersection counting from the upper left corner of the3 H# c1 q! Q% v3 j# b/ A
                  ;; world.  -1 for non-intersection patches.
" z' S% J6 l6 i+ z& y  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
  j/ R# D8 ]. x: J" Q: s5 U  auto?           ;; whether or not this intersection will switch automatically.
- |' ]# K6 G% ^                  ;; false for non-intersection patches.0 P, b# s9 s3 d* \" E
]+ ?8 L" Z9 T1 u0 m) u* G- [
4 C7 k7 y  m" R5 f7 j

0 \& V* \9 s9 R7 f;;;;;;;;;;;;;;;;;;;;;;; r4 S; v: ^/ @0 U; C
;; Setup Procedures ;;. u1 o: c% V/ n: E5 ~! @
;;;;;;;;;;;;;;;;;;;;;;, h% K7 w' W4 L6 N5 W7 z

: o$ R0 A4 h2 V' m2 a;; Initialize the display by giving the global and patch variables initial values.
2 s  @$ E5 C4 t- L;; Create num-cars of turtles if there are enough road patches for one turtle to$ Z& J) G0 p* B
;; be created per road patch. Set up the plots.
" X3 T8 W" ^) w8 X2 {& m  Ito setup
/ |% @& |* F, w9 F2 i1 V4 H7 v  ca
' Z( g' F- y) U: y, I  setup-globals! N' k% t& P2 p" ~: p4 A$ Y1 N
& b  G+ `" W8 }  C  B
  ;; First we ask the patches to draw themselves and set up a few variables, {- J5 P/ B. T+ O) ~
  setup-patches
4 L0 q! V' N  C. s- g# p" G5 ^  make-current one-of intersections! b) V0 K# r2 k
  label-current
$ j$ n6 u  R" }" b* J9 K0 v7 u9 C2 D$ |# q5 \) P- Y3 ^: d& b% `
  set-default-shape turtles "car"
* m% L! _3 U: G
# w8 L2 o. B0 j7 ]  if (num-cars > count roads)6 |7 o' l7 s* b; d
  [
2 @5 ~! v. N8 x" k0 ]! U5 m! k. ^    user-message (word "There are too many cars for the amount of "# z7 ^' t8 n& M9 r! n( z
                       "road.  Either increase the amount of roads ") h4 z: r4 z$ T9 J$ G5 r
                       "by increasing the GRID-SIZE-X or "" W' V' s8 P: ~) c9 `
                       "GRID-SIZE-Y sliders, or decrease the "! q: H7 d8 W8 o0 D3 L
                       "number of cars by lowering the NUMBER slider.\n"1 ^. C4 s9 R9 ^! M& U
                       "The setup has stopped.")
! O/ X; I7 p: @$ ]6 f# ]    stop4 G  f" R. M2 T, @$ G- U8 g
  ]+ W8 }- q5 R: u3 e- {: {0 j

, x8 ^! ?2 e: V/ J  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color) U7 ?6 ]$ j* ?1 D3 D
  crt num-cars6 L( U& d3 v( B/ e
  [
+ g9 o/ r! _9 Z3 [* p& ~; \    setup-cars
- ]! J! d4 d1 o$ Z7 H, H    set-car-color7 j. u0 L8 {' @! o4 a! I: k
    record-data
- ?' ?* r4 c1 j# O6 Q6 ?" M  ]2 ~; f  {% f: S5 P5 \
/ s- Q* Z5 C% W0 X) U
  ;; give the turtles an initial speed# f  t  l2 F% I2 _/ M9 C
  ask turtles [ set-car-speed ]4 h$ w. q: b8 Z6 g. |
6 i* R" K- m+ I
  reset-ticks. j" A9 B; D$ E  G  w+ m$ O
end
* ^0 }3 K8 L7 a. d/ ]
( W% ?* t8 m' \) D$ g/ g;; Initialize the global variables to appropriate values4 Q. l( p+ ~0 w0 |
to setup-globals+ v4 w1 w3 p+ a3 C
  set current-light nobody ;; just for now, since there are no lights yet' I+ ?  {$ D" k& A1 }0 {
  set phase 0
0 R% K0 x' B" v! N% J( p$ r/ F- p  set num-cars-stopped 0
! [1 M8 X' J" b, M0 O  set grid-x-inc world-width / grid-size-x
: c* x" N5 O: Z( ~) c( x$ l% `  set grid-y-inc world-height / grid-size-y/ F$ x0 u2 y7 H" {

, G- |) ~; K! x! o9 x5 c# n  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
! j* V( t3 X3 O, s+ k) ?  set acceleration 0.0996 T% y# n4 j: C3 k  @6 Y1 r
end5 b- L8 ?% f, H. I- g
8 s, g; e  I% J4 }
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,) ]! p- u+ t1 X1 f, z! g* y
;; and initialize the traffic lights to one setting4 B; l( M- w0 L/ I2 [6 k; T
to setup-patches& h7 ?% ]' x' Z* r
  ;; initialize the patch-owned variables and color the patches to a base-color
$ S1 m( k8 s8 _8 d$ P  ask patches
3 _& n, J. O" M6 _' M  [
- y$ q. M7 g5 P    set intersection? false
/ k2 c: D; V6 n/ F8 w    set auto? false( h) }) S: i$ V9 H3 x7 W5 P3 }) a
    set green-light-up? true( J! ~  w! E$ C" m
    set my-row -1
5 ?5 T' a, S& U' {% K0 j    set my-column -1
: Y+ V8 M! `7 N& @- A2 C% d8 V5 P    set my-phase -1& D' a6 T6 E6 E" [* I$ J# m' N
    set pcolor brown + 3
6 I5 X: J1 I6 C; U- J; ]  ]& H. n0 v4 O1 @0 v, D; N5 D

: ^. Y4 z: L/ \' C) B- F  ;; initialize the global variables that hold patch agentsets- m6 }6 v/ C/ F7 c* e" k
  set roads patches with" R) o- D8 i2 {7 i
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 Y" Y: `  [# F6 U9 }    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 {: A& e; M! f4 `$ F  set intersections roads with# l; x/ k+ N; ^, A3 n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
7 r  G9 H6 q7 ]" p! y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], I# N; f; H" V1 g# s
- e: N( n& T+ ?) s, y
  ask roads [ set pcolor white ]
6 f  t! A6 n- @& B0 ~    setup-intersections# c0 t8 V7 i5 |$ G1 ]
end
- J9 c6 i; x) ^! x; q4 z其中定义道路的句子,如下所示,是什么意思啊?
8 _+ y7 V& \- K7 Q& f1 t set roads patches with
) {& |/ O( A! ^0 Z, O" W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ P0 j& U& h0 @
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 u8 u5 o5 C+ W5 v4 P% \  T/ F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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