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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。) n6 e: {8 Q0 Z$ A& Z2 {) \
netlogo自带的social science--traffic grid这一例子当中,% w$ o. B& A0 }, A2 N+ H
globals5 `6 I2 T  f) W' b
[; P5 j* l: I( o% c" o$ @
  grid-x-inc               ;; the amount of patches in between two roads in the x direction6 f! h2 O$ ]( z
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
6 a! g. Y7 X  ?  b  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
  K" ?' E6 j% K; ]) E" y6 ~                           ;; it is to accelerate or decelerate
/ F# b1 X2 _/ ~5 }- k5 g' A  phase                    ;; keeps track of the phase9 F5 U& u' `3 H
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
! D' {, m2 t, E0 N, X  current-light            ;; the currently selected light
3 g# Y' V- }) ^5 d
9 Q  M6 e4 \5 j8 A/ E4 y4 Q; y  ;; patch agentsets
- _6 G! x9 D$ H5 z  intersections ;; agentset containing the patches that are intersections
7 y# E8 j' Q. O" s$ M) j  roads         ;; agentset containing the patches that are roads
; H9 V0 ], S, F  a, U+ a* s/ X; o' M]; ]4 N, D- l' t; l! ^

9 u. @9 o& b8 j) V* ^4 Z+ T. y5 vturtles-own2 V: \6 Y0 n0 v, |' C# j5 K
[! y6 I$ `" j: ]7 H8 V, A* c2 U
  speed     ;; the speed of the turtle  _  V! S9 L/ W! S7 K3 P- b% k  N$ B
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
+ e, m1 }- \7 {  wait-time ;; the amount of time since the last time a turtle has moved+ O3 ^$ G" r" N+ f8 l$ I9 \7 k
]4 A. S( E7 C& O& o# c! z

& s7 R& t$ e8 ]+ npatches-own
- w/ G: v" ]' o  {[
* @9 G- `$ u9 E6 a  intersection?   ;; true if the patch is at the intersection of two roads
' h. n0 f* t+ J' ^# t( s' L. s0 {  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
* n3 H9 t8 K! P" N3 r0 W                  ;; false for a non-intersection patches./ o6 v2 r9 d" ]* |
  my-row          ;; the row of the intersection counting from the upper left corner of the
# }7 S0 }6 K" V. p# [" z2 n                  ;; world.  -1 for non-intersection patches.
" N& }7 N, q3 c% A. N, [  my-column       ;; the column of the intersection counting from the upper left corner of the3 r! m4 ^: [4 B
                  ;; world.  -1 for non-intersection patches.3 t. u; O0 z8 G
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.8 {$ x+ V: H2 ~% U3 a; E! v
  auto?           ;; whether or not this intersection will switch automatically., t" n( t- w8 S, T- b5 T* I
                  ;; false for non-intersection patches.: N$ v* ]! u+ v( l" u  F& f% P
]0 M$ }* w- Y9 X" Y7 G
5 @! n% |/ Q$ a, B* @

+ `1 G8 }$ t, E# U+ a$ n" t;;;;;;;;;;;;;;;;;;;;;;% @9 b) }: [) f; z& j) B! K
;; Setup Procedures ;;, Z4 A1 e" d) Q# G9 C
;;;;;;;;;;;;;;;;;;;;;;
5 x/ m% i5 R6 i. `+ N
( q8 D" v- w7 c, R( G6 v;; Initialize the display by giving the global and patch variables initial values.& w% H0 r5 c- ^& P; y
;; Create num-cars of turtles if there are enough road patches for one turtle to% l5 @0 b. m+ ?6 d
;; be created per road patch. Set up the plots.( n3 y$ j1 u, w$ B! {
to setup3 C! e: p4 u3 {9 V: C
  ca8 R, s9 I7 s1 U  Z/ x
  setup-globals
; t" z# O1 H6 r4 J+ k
0 t$ P" R2 i4 e" J3 k5 p" ?  ;; First we ask the patches to draw themselves and set up a few variables/ J7 z, E: d3 A/ l6 h) B
  setup-patches9 F1 I0 g/ r4 @0 _% S' ~
  make-current one-of intersections
/ e5 T/ \1 I& i1 c  label-current5 R* Y9 E! p. f8 _

" M/ z: A: J6 Y3 F  set-default-shape turtles "car"
1 |) C$ p. B7 ^' {4 ?. M  G. @0 i. o+ v
  if (num-cars > count roads)
0 R% S" w/ q, r% }, e  [
+ R8 e( x2 b+ C& j6 M    user-message (word "There are too many cars for the amount of "
* V: k1 T7 x# J! C                       "road.  Either increase the amount of roads "( e" T! s) `) x0 `0 E6 ~" b
                       "by increasing the GRID-SIZE-X or "
6 z$ O- z' x2 M  u# {* O$ C                       "GRID-SIZE-Y sliders, or decrease the "
3 O9 ^- m* |" }# g1 O                       "number of cars by lowering the NUMBER slider.\n"
: |6 f$ p  |( H4 f) b+ i. b3 R$ S' w                       "The setup has stopped.")
6 v& n  |: Z5 ^, G( ]( o    stop1 {) f, ]% C# s; X
  ]: M2 e0 ^  H  k3 v! q' O: j; Q2 Z
, k/ D2 m1 o* o1 n
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color/ a% Z3 n5 `6 h- k" j! z( e5 u
  crt num-cars0 S7 g. T$ W2 m* P; W" \/ P
  [
+ ?" \- e; b. e' q    setup-cars1 f. N5 Y! o3 w- F/ V# I
    set-car-color
7 T/ E, H0 r/ W2 k) t# c    record-data
* X' I) A4 c+ ?, c5 H1 ~  ]1 b/ y9 [+ M+ Q  B4 y0 x; G3 y; b

2 m6 U. C5 e$ }2 b% p2 `- e- L  ;; give the turtles an initial speed. g6 D. r1 S3 B  V
  ask turtles [ set-car-speed ]
( w  S( b/ n9 A& K8 q1 @$ K3 }
! u2 Z! s: I3 K8 J  reset-ticks
4 F& |8 P# v- e) \/ s2 z' _# C8 wend
* [' r5 E4 G8 a% j5 v. f/ g7 T- o+ C( H& h9 c4 l
;; Initialize the global variables to appropriate values
  D7 m3 U+ l  [to setup-globals
+ \& }8 f* k! W) X6 S  set current-light nobody ;; just for now, since there are no lights yet
/ E8 p, T7 c0 m  I0 W- m  _! d  set phase 0
' U4 {( j4 M5 ]2 Z. H, X  set num-cars-stopped 0
# z. X' T) f5 K/ E  set grid-x-inc world-width / grid-size-x6 F/ |5 V9 z' I5 m; D
  set grid-y-inc world-height / grid-size-y1 j% A; b5 Z. \1 V0 p
  k! n* C: s4 K7 i+ k2 ^% q
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
6 U* _. y. w" g, C2 \  set acceleration 0.099
, w4 q' }7 ]# ^: ~7 H' c5 Send0 D  K1 q5 g+ k  s8 e" Y! z

- z$ A" G' Z% Y# |5 t4 {8 v$ x;; Make the patches have appropriate colors, set up the roads and intersections agentsets,: A2 J3 [2 Z6 u0 F# O
;; and initialize the traffic lights to one setting
; {( O  R$ |* l8 ]5 d! [# |to setup-patches2 K# V* `. S7 Q% P5 z
  ;; initialize the patch-owned variables and color the patches to a base-color& J1 t# p$ F2 Q& m, p* _
  ask patches
2 i! U4 i$ \8 |, |* l  [6 R% ?5 _% x8 M2 K" _0 `
    set intersection? false2 k- q- g' {" L9 h
    set auto? false
& i8 b% k* v6 h, }8 c    set green-light-up? true
$ Y" j/ O. w2 P; g5 \    set my-row -1/ W/ P* M  B3 o8 l4 O  a" y
    set my-column -1$ c% z3 z8 d4 S
    set my-phase -1
( J. [, j% J% ]& ~, F- u, `4 l5 d    set pcolor brown + 3
$ s" T! I8 t6 |1 w& S+ }: `5 F9 C  ]
! D2 e% [1 f& Z% W( p5 `! H' }, W. ~( p) y5 t% l
  ;; initialize the global variables that hold patch agentsets
! p5 K4 [' e( Y& `4 u3 J  set roads patches with
" j- a8 n9 C& S  H- C* j# D    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& {: V9 b# y9 k; P  \2 R+ P    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! Y7 _& _! b' e$ D# \" J; T
  set intersections roads with; K: i+ o+ f2 \  W+ ]( n# F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and8 @6 N' @! D6 d& i& t) ?
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. d2 o; z+ F+ ^" @1 A/ B9 y' {

" u/ ?3 Q9 n4 v( ^  ask roads [ set pcolor white ]
3 c9 J  M3 w/ q8 J7 z    setup-intersections
* \: L! B* C& J6 w3 U0 ?  J' C/ Bend3 D' M; K4 g9 z4 k
其中定义道路的句子,如下所示,是什么意思啊?0 {( }+ {! N* ?$ I
set roads patches with; ~  {& R& ^5 M& c  S8 {$ Y9 D' R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
' l. M: L) T' g7 k" ]6 S    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: @6 g3 h1 t: f" n6 P0 R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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