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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。; I$ M+ Z' L0 x
netlogo自带的social science--traffic grid这一例子当中,( R. H& ~7 y8 w9 \3 {1 g
globals  N4 d. W9 s1 B0 B: J( m/ A0 m
[
! {2 k: v4 e1 |) [5 [, O  grid-x-inc               ;; the amount of patches in between two roads in the x direction$ s6 x8 b4 d! W4 \. A
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
1 S/ G  V6 y, K# E3 }3 Q3 o  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
. P8 @) S$ [4 K: ?) C/ z7 l3 E                           ;; it is to accelerate or decelerate
& y. L: s6 y8 r  B+ q8 X0 ~  phase                    ;; keeps track of the phase
+ b( W9 ?  V9 {1 b  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure  h5 O" S2 B6 S1 m8 A/ h* V. ~5 }
  current-light            ;; the currently selected light
0 X' ^8 f1 M7 R; u# C) G" j1 x  ?1 N$ \; A' A9 Q( Y6 Y
  ;; patch agentsets& }* B# e) A- P+ a; i
  intersections ;; agentset containing the patches that are intersections
8 D: P% |7 k0 G; y  roads         ;; agentset containing the patches that are roads
7 Y1 e0 A/ X# E) N5 g2 Y]+ `9 J( U7 S" j" u# F

2 p3 @5 |' E4 @4 u* \8 V+ cturtles-own/ p& x: I3 P9 r
[$ i8 p# k0 e" j+ b
  speed     ;; the speed of the turtle5 u8 ^- v2 O$ v/ t. r
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right. }& d% Z6 _+ i/ k& x6 W
  wait-time ;; the amount of time since the last time a turtle has moved
( g. o4 a) K+ m) O, x]
3 {9 o6 |) K4 ^2 Z2 [( B+ `. c
- W% f+ K2 s5 J2 l- ^( s" Lpatches-own. L. B0 _: h8 ~9 N& X
[
6 F% {1 y6 T8 G0 T4 A* s  intersection?   ;; true if the patch is at the intersection of two roads
/ u' v! k, F4 ], n4 w  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.1 I  E# T" `) M  L5 C" A
                  ;; false for a non-intersection patches.
% v5 G8 i0 Y( Z, n0 G  my-row          ;; the row of the intersection counting from the upper left corner of the' m; W1 Y! l# d
                  ;; world.  -1 for non-intersection patches.! T8 e0 f# g! g& u4 d8 y8 `' ?
  my-column       ;; the column of the intersection counting from the upper left corner of the
8 Q, ]1 n# |/ T$ p                  ;; world.  -1 for non-intersection patches.
! @* i9 W$ f! h6 ^9 e: j  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches., C! q: g! p; I
  auto?           ;; whether or not this intersection will switch automatically.7 A+ v3 M7 I( o$ v+ v& u
                  ;; false for non-intersection patches.; [0 Q- ~! y. l% ]6 D
]5 c8 g% s/ u$ A* Z* k* u& Z/ B
0 f4 {) h- D; {+ c
# c' s3 E  l5 M) e! E6 ^+ _3 E
;;;;;;;;;;;;;;;;;;;;;;* E0 ~- \, a; |8 L
;; Setup Procedures ;;
+ N1 j( o- P2 U5 L% Y;;;;;;;;;;;;;;;;;;;;;;
% Y' H$ h& J; o& e8 {, `
- r8 C- R+ t4 l; z;; Initialize the display by giving the global and patch variables initial values.9 j1 C! ~6 T' M( D
;; Create num-cars of turtles if there are enough road patches for one turtle to! c  m, [8 {5 b3 N$ E
;; be created per road patch. Set up the plots." W; B3 F" {$ b3 _5 e! I
to setup
5 ^" x' d! P  H) `  ca
6 X/ E( j& N& P+ y6 c: E' O  setup-globals' y9 \3 |) |& B5 b4 x+ G
+ M* j! ~  ^0 N  ~+ V7 [4 m& u
  ;; First we ask the patches to draw themselves and set up a few variables
9 u, B  Z2 }4 _2 N  setup-patches
$ [3 K$ {  r, D; ?4 y9 r. {. f9 C  make-current one-of intersections
' i* K: T# q1 U/ w: n. J/ b  label-current; {% Y: P3 d' O5 D4 M6 G' |" s  |2 k
- E4 Y% Z' y+ @) v
  set-default-shape turtles "car"( G$ o3 M  j( h0 k( u

5 P( _& i( x0 I3 g9 E& {  if (num-cars > count roads)
7 Q. n- q0 G, i% f* K  [
# j0 ~7 h& i1 r    user-message (word "There are too many cars for the amount of "
( D% c3 o1 u0 H8 }) h6 R4 u4 e                       "road.  Either increase the amount of roads "
8 u6 u0 G. J1 D- p+ I1 z                       "by increasing the GRID-SIZE-X or "
3 @7 y4 x4 c4 v& b                       "GRID-SIZE-Y sliders, or decrease the "' r# k- w4 ]2 d% m2 a
                       "number of cars by lowering the NUMBER slider.\n"0 W) S  \" l- G/ R
                       "The setup has stopped.")
# D- W0 |9 i% x" {) ~4 |    stop
& C* r" J- V/ W. z7 Q* v* g  ]6 o2 S4 o4 j' |

& i7 M+ _5 p% g, V: |0 h. q  c1 g$ a  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color; s2 p4 G0 n6 [0 p. l- a
  crt num-cars
) B; }- L6 u# ~  K- X. s8 W& u  [
. C6 I5 [6 P! q- z    setup-cars' F; s( m% u3 {4 T( m
    set-car-color( w2 j: v, j! b; T
    record-data/ [/ ^& @/ a* G8 `  \; J3 R
  ]
8 W1 T) |5 a( |3 k$ X& b2 s' x; ^  H
  ;; give the turtles an initial speed: C8 c# {' [2 Q+ H5 m' I5 n$ G
  ask turtles [ set-car-speed ]
* K- y9 C+ t$ Y+ o/ {3 n8 {
, C) ?& F2 t7 w8 I& f& d  reset-ticks5 \. L# s5 x$ w% g* ?. k1 L
end
, o  U! n. s7 i( i9 S, f6 X. R2 x+ [5 a4 M9 d8 T
;; Initialize the global variables to appropriate values
# [" K( I7 l4 o7 q/ zto setup-globals
( R( p' y) A$ I3 u% E! m% P  set current-light nobody ;; just for now, since there are no lights yet
3 t3 A2 H  T5 z1 o  @) C2 I  set phase 0
/ y7 M" e  F( x2 U' r: R. Y- ?, @  set num-cars-stopped 01 b4 K3 v' I  a! d$ m- f
  set grid-x-inc world-width / grid-size-x8 k. t; s: r2 q+ f4 j: N$ w9 u4 n
  set grid-y-inc world-height / grid-size-y
, }* o6 A* l8 |
3 N) Z: |) Q0 s  N6 [8 n  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary# h8 }/ ~( i! ^5 U% }  Z, D  x
  set acceleration 0.099  u/ U, R* P4 }3 f3 _5 d1 K3 K
end6 J3 Q5 Z* x& O) O, j  x" `7 b5 ?' `

! q0 r# s1 M/ U. a: Z;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# c- X9 Y9 C1 u8 E( y;; and initialize the traffic lights to one setting
! Y2 C2 a# s7 \8 Sto setup-patches: K- B4 d' f& W( v; C5 ?- U
  ;; initialize the patch-owned variables and color the patches to a base-color
: H$ s/ d( `; I  a! V. }  ask patches! l3 ^6 p/ r$ w/ U% ^# T
  [# U% q" ]/ i1 ?# Q9 n- Z; r
    set intersection? false
" k: }) n# O  h6 g0 F; J  \    set auto? false
3 i) [/ T: R/ r: i  a1 o    set green-light-up? true
& |' s. Z4 K5 p    set my-row -1
/ c3 f9 {5 k4 i  l& P2 |    set my-column -15 `; Q; J( a, ?( |" I
    set my-phase -15 k9 l) w6 Y# Y( G% W5 a; d
    set pcolor brown + 3- N. t* S; ]4 h1 @: f% o% x
  ]( v# `- v$ J$ \5 L7 _+ V2 X

) J9 R$ \2 K0 x  _# z% o! ~  ;; initialize the global variables that hold patch agentsets
# D. X; v- S5 E4 Q/ H4 T/ N  set roads patches with
& b4 d4 P" G2 l+ i3 o$ u* l- R0 N    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 I) ]: g. P- x" E8 R
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], p* x5 j* |6 d- q$ V( z6 E
  set intersections roads with, Z. A8 C) v4 }0 S# k
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and, V& G7 G& P/ p& s% T+ f+ ]& j3 {/ [
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& j/ @, s/ S  V* Z4 f! f5 [2 m3 u
+ g  v  A& j8 w, R
  ask roads [ set pcolor white ]
+ E9 y; a. V# {/ @4 t7 @    setup-intersections
" [( n! {; H- ]6 z. ]: Tend, j' g6 v" J$ s# R0 q1 e5 e. h
其中定义道路的句子,如下所示,是什么意思啊?
, X6 [2 h" O. d' o7 n4 S set roads patches with( S! _4 G8 N6 E0 J, f
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* u6 d4 y+ B; m1 Q- D* [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' J+ i. |% T# b3 c7 x: |* H6 z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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