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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。9 A& K1 ^5 L: ?) T7 D
netlogo自带的social science--traffic grid这一例子当中,7 @0 {" o4 m# R/ @+ Y$ |
globals
+ _& e5 `3 y# F9 i6 \[2 N% d, J8 E3 ^4 h9 z6 ~( j
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
" A5 F. N. C9 D% ]* E" K2 A  grid-y-inc               ;; the amount of patches in between two roads in the y direction" H7 H5 r" \' K- M* ]8 {: F
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
! j2 o# }* O: x. a0 {                           ;; it is to accelerate or decelerate
+ C# z7 f' @, a) G/ S% ^3 |  phase                    ;; keeps track of the phase2 [6 q6 a% \" f% v5 k/ _
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure# B4 v9 S6 e+ X4 @  ]4 V1 A, o
  current-light            ;; the currently selected light# x+ r8 P2 K! f7 e

- I3 w1 c0 n5 u9 {4 O# D  ;; patch agentsets
" m# Y/ [/ a2 d1 s  intersections ;; agentset containing the patches that are intersections; p4 D9 e' K3 X6 t) p& ^6 R
  roads         ;; agentset containing the patches that are roads" m( [: S3 q# \8 C9 u
]
7 O9 n1 [" Z# r, {' L! P* A
- K- K+ V. w! @2 x2 I  f; T. d2 Oturtles-own; f% X3 ^; r) }$ \' |, ?+ C
[+ t4 `. f- W. y3 s7 B
  speed     ;; the speed of the turtle
4 R. `. w9 L9 Q4 i3 ?4 p3 ]  up-car?   ;; true if the turtle moves downwards and false if it moves to the right, F# L2 m( @0 @- Y
  wait-time ;; the amount of time since the last time a turtle has moved
" a6 ~6 |/ m6 U" t) R]
0 z- |* g' h: Z+ w
6 }8 `2 e# ~4 p$ ]. qpatches-own1 [% i' V+ y6 c7 a, u$ Y
[
( |) X  U1 r) V1 g! ?1 ^  intersection?   ;; true if the patch is at the intersection of two roads
+ L6 \9 n# }  o- E  ]2 _& M  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% d/ ?- M4 X, ]4 G: z                  ;; false for a non-intersection patches.  X) x( \# D. r9 J# o' h5 [
  my-row          ;; the row of the intersection counting from the upper left corner of the
) e1 @! K, X% W4 v                  ;; world.  -1 for non-intersection patches.: M! O6 G- _6 K5 ?8 x1 V
  my-column       ;; the column of the intersection counting from the upper left corner of the
: |# V1 ?* W, Y; B) q                  ;; world.  -1 for non-intersection patches.% Y) W0 @( M7 A" C* ^* t! B0 I
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.9 e, L0 t  a4 ], C- E
  auto?           ;; whether or not this intersection will switch automatically.
( }) F0 F4 \( _9 m                  ;; false for non-intersection patches.
0 m- B! N8 x; n9 n: r! w]
$ r$ v% C! k3 r' C3 i9 @- J8 t- j- m$ U' c% p! S$ j* p

' E2 d' B- W$ _' f- r;;;;;;;;;;;;;;;;;;;;;;* l; X& w. j8 \% e
;; Setup Procedures ;;* S0 [* }% c, i1 H) P
;;;;;;;;;;;;;;;;;;;;;;
7 p6 X  X/ L+ S7 l6 ~
1 G6 U- Q0 d' _+ `;; Initialize the display by giving the global and patch variables initial values.  W) p0 P; K5 u& z4 ~+ N
;; Create num-cars of turtles if there are enough road patches for one turtle to( y9 I) h3 U, s5 m
;; be created per road patch. Set up the plots." n8 d% j9 s  |
to setup
  i! J7 l9 Z( }* e9 C. b# `5 t  ca( s; d0 j, X6 O6 n
  setup-globals5 I% m4 n: o" F* g+ u  ~. Y

8 v9 A, Q2 G) i5 ^% p  ;; First we ask the patches to draw themselves and set up a few variables
8 e# i( c1 G( L" k$ k  setup-patches
& T' y/ \/ ?- ]  make-current one-of intersections9 r5 J; D9 P: S) z4 t
  label-current& [7 ^+ {  T5 N, g
, v+ C9 H0 O( N+ D3 g# t$ F
  set-default-shape turtles "car"
, M; x5 z/ o3 Y, }+ N& v8 W7 U& n6 E+ ^% f) Y
  if (num-cars > count roads)1 F, r, ~& B" ], o/ l1 g" n* c
  [* X3 b& q, E2 V$ b! e; B
    user-message (word "There are too many cars for the amount of "
- E) j3 Q( D8 c, h                       "road.  Either increase the amount of roads "; R: R1 N; ^- U! e7 g
                       "by increasing the GRID-SIZE-X or "( v  K2 F+ I; e* b8 J
                       "GRID-SIZE-Y sliders, or decrease the "7 M2 ~( x0 ]0 |
                       "number of cars by lowering the NUMBER slider.\n"
9 j4 f) t, {# X1 X% d, M5 O" f                       "The setup has stopped.")6 ~- T3 B& B: q* z! x4 a/ }
    stop4 G+ l2 m' k9 l1 [
  ]
. b  g  |- Z( _" W2 N1 u: G8 {1 W0 C4 t6 m
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color& g7 h1 a/ C- V; b3 j4 l
  crt num-cars4 C8 X" b1 Q3 ~4 ^0 c
  [
; C- E# d( Y; R1 h4 \/ e& z$ R    setup-cars
5 C3 q/ L9 Y  z5 x0 P    set-car-color" c/ Y* }6 Z% |  ]' E- J6 p# }0 ]1 D
    record-data
( y4 _- F# @( }2 Y! \- p. }  ]
7 z* w4 V+ n+ k* J# e: \( N0 U; W% |9 h% i1 R
  ;; give the turtles an initial speed7 Q( N& k" J8 ?$ y! s* U
  ask turtles [ set-car-speed ]
. B, Z6 z" S( O1 w
0 {' [$ Y# m. ^7 a  reset-ticks: z0 t  S( ^% A( ]9 R" c' S7 Z
end
% k" [- n1 P# r; e# ^. {# y* n! k: e  k
;; Initialize the global variables to appropriate values( b; }2 i6 u( @/ h
to setup-globals) |$ H5 Z/ n# X
  set current-light nobody ;; just for now, since there are no lights yet) m( I: y- ~+ O1 \: _4 L! z
  set phase 0
, X5 a2 P  ]( a7 Z+ s8 @3 i4 I( f/ [3 d  set num-cars-stopped 0
. _; U2 [$ Y  w  q7 Z  set grid-x-inc world-width / grid-size-x( ^' g# u. M) J
  set grid-y-inc world-height / grid-size-y
3 X1 _6 A) }' t! X) q* y
4 T+ r4 n$ n# W+ I1 h  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
  g3 h/ c9 d) Y$ `  set acceleration 0.099. n7 \/ q2 a" X0 ~
end, o5 u) `. m% L* _7 M
; S- i  {& g6 X+ i
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,. n, F4 ?" e3 ]8 r$ x  J3 b- G
;; and initialize the traffic lights to one setting$ b3 t' Z5 C1 \, O* U2 r9 ^
to setup-patches' m, p$ r7 ^. X! B, k% M
  ;; initialize the patch-owned variables and color the patches to a base-color
) H6 S% n2 v5 [! `( G6 Q  ask patches
* f' d+ @. v) a& c0 I. J5 R  [
+ f. z' {& s1 {7 p0 ]) J5 ~# V: f2 F    set intersection? false/ u( a, F9 F3 h, Z
    set auto? false
2 S2 w3 _6 y& Q1 z1 d. Q    set green-light-up? true& s9 `- o0 z$ ~) @! B4 ]4 n+ ?' l
    set my-row -1
, F' D. M7 c; @* T6 h; a" G    set my-column -1
  K) j6 Y+ |3 k4 C    set my-phase -1
8 \& K1 ^* p" f0 p# \! t# ~    set pcolor brown + 3" y- |( Z' f$ r' p. ~2 |. j* y
  ]
5 N  R5 S8 u$ A' O- k0 n2 g& G( F- G2 [0 w$ j8 w( x
  ;; initialize the global variables that hold patch agentsets
9 H! W* O. @0 ]+ d! k  set roads patches with
% j! o  ~' ^! q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or8 |8 ?- `; S: e- x& a
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- e' j0 h& z# T4 \# N  set intersections roads with
" c* e; ?8 N4 X    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and5 q$ Q5 b  Y) v9 S
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& a) }6 {2 L6 [
) J7 k8 e, B0 k- H, Y# {$ Z  ask roads [ set pcolor white ]* ]# K' T( N( U& l0 o+ @# s. L; j
    setup-intersections
: e* \- |: S% m8 V3 k; Zend
9 ]2 O) e, V; q! \1 H% @其中定义道路的句子,如下所示,是什么意思啊?
6 O( R! n7 y: A set roads patches with- p8 z5 D% u. u2 ^
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 n% I' q2 Q- ]( b
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) ~! R( ], c- D' D6 D- m& q5 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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