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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。; S' ?0 ~! L; H5 D# m
netlogo自带的social science--traffic grid这一例子当中,
: D$ r6 l2 H1 X! p* zglobals
% f0 G9 Y2 y1 h1 ?[
5 v0 r7 t+ n' @: Q0 v' s  G; _+ f  grid-x-inc               ;; the amount of patches in between two roads in the x direction
$ e2 k: n4 ?' k, ~2 g$ G  grid-y-inc               ;; the amount of patches in between two roads in the y direction- J" H7 O6 l) _+ ^; m+ T
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if3 R2 \  n5 r0 v
                           ;; it is to accelerate or decelerate
: w- h/ J1 N4 O. D* [4 b  phase                    ;; keeps track of the phase7 k9 b5 E  I$ p, @* f
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure" U1 |1 y4 F  ~1 t0 x& e' x# O" ~
  current-light            ;; the currently selected light
  n$ Z) M. U9 {2 p  [" h
7 N. r+ Q) ]& d3 @0 K  ;; patch agentsets
; X8 w. F# d5 O( |( w  intersections ;; agentset containing the patches that are intersections' C) i# f; |0 A2 `+ ?. h9 A3 D
  roads         ;; agentset containing the patches that are roads1 k' I" {. \( p* S
]* g: ]7 H& `- v. P8 P

& }: {8 K4 _" u" g7 t& ]1 \turtles-own
4 j( f; U/ j2 k2 c. v: n[4 R) |% |1 Q. d: X% W4 g
  speed     ;; the speed of the turtle5 V& p4 ~- _  D0 V% E* A
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right: Q" [: j, k  o5 k+ H
  wait-time ;; the amount of time since the last time a turtle has moved) I: W3 ]* _8 z6 n: i  x
], q: E5 T/ K. z9 I9 O) s

6 Q3 A# N( F: |patches-own
% G7 A, v1 ]$ C5 T; }: P[
* M  x/ X' v# r( q; H) r  intersection?   ;; true if the patch is at the intersection of two roads8 x: G9 ~% k: r; ]5 K3 @4 d
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.1 m+ u; u, l7 L* s" {& d( W% H
                  ;; false for a non-intersection patches.
; X1 b; I3 y+ ?) N- x3 G1 \  my-row          ;; the row of the intersection counting from the upper left corner of the/ ^/ r: D8 N* T/ m5 J
                  ;; world.  -1 for non-intersection patches.
) M7 z' n1 P. d8 o  my-column       ;; the column of the intersection counting from the upper left corner of the5 E: v2 D0 M& l* _* r5 c9 x
                  ;; world.  -1 for non-intersection patches.7 m  T; G3 u! {# F; O+ i7 Y2 a
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.! z3 Q4 r" `2 m- d
  auto?           ;; whether or not this intersection will switch automatically.: V# r, n: ?# [
                  ;; false for non-intersection patches.
& b$ y% E$ H9 Q4 S]
$ }2 K' ~  `6 B3 z  B. D8 F# ~, ?( V
* Y7 ^1 X4 o- P4 @1 o
# V% Q! {- F& n$ ];;;;;;;;;;;;;;;;;;;;;;
* \( U7 ^% ^$ y% g3 t1 r/ u;; Setup Procedures ;;
* ]1 O- C/ i4 F* j9 r$ _" E;;;;;;;;;;;;;;;;;;;;;;
3 b: c- Z2 R3 v, N, H, V/ \# P: E5 b9 r& R8 O, _/ a
;; Initialize the display by giving the global and patch variables initial values.
4 H. y, u3 U. M$ q! b;; Create num-cars of turtles if there are enough road patches for one turtle to
- j+ O# W3 a# r2 U6 [;; be created per road patch. Set up the plots.
! Q% ?6 `2 S8 K1 W" B8 s7 i( Dto setup
5 R+ O8 _& Y8 E/ [! B3 Y2 g  ca5 l1 Z+ ~7 a- U7 n' o' S, ^* U
  setup-globals
  _6 Z; I6 @+ h* p9 D. t) _/ N+ E# M# i* u7 A/ C- D! ?6 r2 n) Z/ I
  ;; First we ask the patches to draw themselves and set up a few variables
1 ~+ o, I. p8 _1 `1 F% o4 b  setup-patches7 R5 x' P4 q/ a0 \2 |7 x
  make-current one-of intersections; E7 ^8 Z. X. u2 }: q1 p
  label-current
( R2 u' b1 U  D" h& h5 b7 Q. ^: ^$ W
  set-default-shape turtles "car"
) n8 n. R. `" K2 ?7 D) g9 T- g4 r/ k
  if (num-cars > count roads)9 h& S9 T7 w4 Z( d* a) l5 [
  [  Q4 _8 t2 q) H2 o) Z, b
    user-message (word "There are too many cars for the amount of "+ h+ o5 z+ H3 D
                       "road.  Either increase the amount of roads "
- h& B2 p' y: U. ?1 {1 m/ P                       "by increasing the GRID-SIZE-X or "
$ G2 N$ T8 |- {# }                       "GRID-SIZE-Y sliders, or decrease the "/ F  s( G! Z$ |3 D
                       "number of cars by lowering the NUMBER slider.\n"
( b, |- {  J% M+ }8 V2 k" o                       "The setup has stopped.")
9 n2 u7 X  y1 G- _! L7 j. ^    stop
3 L3 O) z! ?, r4 v4 \  ]+ Q+ `* A, p2 A" ^4 Z+ Z
7 P2 x6 j, V! T4 F$ }
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
/ t/ I' }, [9 }  crt num-cars! b8 M. ~' h  X+ I" {1 \% T
  [
! W! Q& Q# I- n    setup-cars
! v( i6 a7 ~3 D4 [; K8 s3 |    set-car-color
. y# y. z$ _0 l, T& v( V6 c4 a    record-data$ H% i7 t; y' q1 c  g7 `7 {: B2 |
  ]% I# n6 s7 Q' C/ {& ^

4 L! N) _' O* j' f. L5 g- C  ;; give the turtles an initial speed& b' ?+ R1 X1 v7 d) p# D
  ask turtles [ set-car-speed ]
4 E& |3 o5 O$ Q$ _9 ~) ~
5 \/ X1 u# M/ l7 Y- I  reset-ticks
: n; X7 y4 L5 X6 C6 s+ Yend
" W" a) Y. t+ z4 y- C: }( Y9 L- P3 \
;; Initialize the global variables to appropriate values1 L  q) T: K0 j/ t
to setup-globals
( K" {, M0 @( a1 Z, M' C! H  set current-light nobody ;; just for now, since there are no lights yet6 Z# Q. S5 I5 L! X. z
  set phase 0
( X) T- d3 j/ Z8 s) u3 v8 ?$ m* \) a  set num-cars-stopped 0
' A2 ?, q$ [) n0 {  set grid-x-inc world-width / grid-size-x9 _) F6 C3 k! d1 r& e9 b
  set grid-y-inc world-height / grid-size-y0 l( s" P5 s/ {

0 R* K; g# D' T* u; A  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary& U* s! f9 Z+ F! ]
  set acceleration 0.099: Y2 I6 B6 k% e6 s
end9 k: M. B" y& v, y; s, k
% }  n( P  p& M( _4 R9 k3 U
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
( O: D; T) a( k2 p1 L! Q: h' _' _8 U;; and initialize the traffic lights to one setting2 G/ b! c3 o7 X- |+ Z
to setup-patches1 v- u, d" M' q: y7 ]
  ;; initialize the patch-owned variables and color the patches to a base-color0 ^4 |" `& _7 X
  ask patches
/ j% M! P9 H; P. C% Q  [
& A+ S7 Y. P0 \9 F0 N    set intersection? false
2 M9 H- s5 r8 i# t# y5 y    set auto? false/ a% g1 z$ P5 i9 _! ]0 u  \, `" A
    set green-light-up? true7 i- t. E5 d+ R, q) w* N5 v$ M
    set my-row -1! D& l, B2 Z& `" i: Q8 _
    set my-column -13 _8 [, a5 W7 r
    set my-phase -1
3 g5 G% ~. M/ M% M    set pcolor brown + 3
- x% h& z: l7 ?2 b8 v5 {: e  ]
" ]1 {1 r8 h3 w7 {+ r6 A4 d: K# _0 f( B8 w( K; [# w$ {7 g* {, r
  ;; initialize the global variables that hold patch agentsets$ L! d8 M- G/ h, e; m
  set roads patches with2 L8 _- W4 Y/ M
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ P5 D% z; X. G; K% k
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' v  a) @( I  B1 S9 \0 s
  set intersections roads with; }; m7 c' e6 T- h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and$ g) C, I# k0 @& c* n3 A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, I; H7 D2 q+ `- @" V( Q6 R" r$ Q5 n' P: ^0 g) ~1 J
  ask roads [ set pcolor white ]: j0 {# U* h( T( P3 c" K
    setup-intersections
4 i$ F* i! X3 D9 i% wend: g$ `$ e! m* u9 H& H( N
其中定义道路的句子,如下所示,是什么意思啊?. d& E# M; g/ b& e  }# x
set roads patches with
+ [  F- T. _" g5 K% J( Q! v4 X    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, b$ q4 ]# }) ]2 D1 P# V% N! y; M" ]    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ {1 V" |& d0 A1 G# l3 S; h5 r* a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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