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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。  r5 T3 V8 R  @- R
netlogo自带的social science--traffic grid这一例子当中,
. |* D/ n7 c" p9 [globals
0 _* M- R% h4 H[
  q. I2 ^+ h$ D6 E8 H3 ?# [  O  grid-x-inc               ;; the amount of patches in between two roads in the x direction
; N, C' y4 W5 B' R/ M" R  grid-y-inc               ;; the amount of patches in between two roads in the y direction
* V* `3 @) p' N) e& A* [* |+ C. _' Y  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
4 w* a4 T1 F; K( H                           ;; it is to accelerate or decelerate
3 N0 b3 ]! h0 |  phase                    ;; keeps track of the phase
$ L1 ?! h+ a; ~7 N+ L" l5 M  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure8 I* g3 ~9 ]  W" W. U) o
  current-light            ;; the currently selected light
/ A' z  h# i0 k! i5 v! \$ |6 Y% l1 d8 x# p( L9 J
  ;; patch agentsets. I. b+ l$ {, y/ t
  intersections ;; agentset containing the patches that are intersections
9 ]- S, a! F+ U  N; H- m  roads         ;; agentset containing the patches that are roads& \8 Q8 H7 M% K7 T* h# |! x
]7 g$ k5 j  y" ?9 V
! W% F3 L) M# C- t: L& N
turtles-own
! V1 n% O" }. Y; @, p[* h6 U- r9 o1 O. z5 a& j
  speed     ;; the speed of the turtle1 f8 K& U% a, M
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
: `8 V1 L( t- G( Z% R& _% q  wait-time ;; the amount of time since the last time a turtle has moved
* c: Y! D* H1 K% f]& m; c8 D% t+ M

0 Q" Y# M* N/ B4 ?* Dpatches-own
7 M# `; T4 _* `% S# O; ?4 p0 A' u# e[& F1 u. d/ {$ Z% @2 s5 V0 t/ b; O8 V
  intersection?   ;; true if the patch is at the intersection of two roads! A+ M# _6 v! ~6 N, y. g
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
+ _* e- Q; ~9 u4 l  f( E                  ;; false for a non-intersection patches.
$ k3 m1 E! Y0 Z# ?  my-row          ;; the row of the intersection counting from the upper left corner of the
/ s% R4 y2 e2 G1 F) f& `                  ;; world.  -1 for non-intersection patches.5 k# H% \1 }7 O+ z* F% n4 o- P' o
  my-column       ;; the column of the intersection counting from the upper left corner of the
  w% |6 s; r7 V" D                  ;; world.  -1 for non-intersection patches.
" J4 i# {& j7 {* p3 w  S- ^  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
( b$ [% f& m  c8 \9 w  s) }  auto?           ;; whether or not this intersection will switch automatically.
- n+ Y+ }/ r9 t! ~/ u                  ;; false for non-intersection patches.) Q- C4 u: c/ V2 F
]
: b5 C1 s' T& |2 |: H3 Z$ [
& K8 v/ s  t7 q5 r! ^
4 V0 ]4 _# x. B2 d( r- @;;;;;;;;;;;;;;;;;;;;;;; K" `9 O- S, F, z# w/ E
;; Setup Procedures ;;
7 s! g0 @7 v1 {1 C! I;;;;;;;;;;;;;;;;;;;;;;
% I; z: Q' D4 K, k# w
1 F0 A1 r2 I* x* p% q0 |; S( B4 Y;; Initialize the display by giving the global and patch variables initial values.
2 C9 o4 a$ v8 p;; Create num-cars of turtles if there are enough road patches for one turtle to
/ T2 H  k# d3 D' U; W6 {3 b8 t3 s. ]5 C0 N;; be created per road patch. Set up the plots.7 X- m0 \+ X/ ?/ i7 q: R' I
to setup
' S5 [4 J5 X) q- \! ^  ca6 S# {+ y# ]0 z# P! Q* |
  setup-globals1 P2 ?* E1 e% P+ f/ g2 W

3 T& M0 G3 G9 p( s4 r, m& I$ q  ;; First we ask the patches to draw themselves and set up a few variables
, z1 t! f$ _+ I1 G  setup-patches6 _3 ^% Q! G9 F. @( J: N1 E
  make-current one-of intersections
7 l9 |$ t6 m; e" G, ~  label-current
9 c3 u, w6 N/ B6 \. I9 L& ^5 |! L
' J4 t9 B+ A, G* Y" J8 s  set-default-shape turtles "car"7 ^) c, r  x3 X" i! O) S9 {* j

" e$ x4 W- n" A" ?# G  m- G1 ~! w  if (num-cars > count roads); J& n' ~6 K8 R* u" V
  [7 w" g9 ~# Z: F
    user-message (word "There are too many cars for the amount of "
% ^1 z; f% J9 e0 f5 o# G                       "road.  Either increase the amount of roads "; ^6 ~- W8 A1 |& N- A' d8 W: ]
                       "by increasing the GRID-SIZE-X or "
& r1 M- P8 I$ Y4 @+ Q: g, x                       "GRID-SIZE-Y sliders, or decrease the "# _" Y. G& P  S+ K4 x7 j! Z
                       "number of cars by lowering the NUMBER slider.\n"' D1 F0 O( Z% ]0 f
                       "The setup has stopped.")( n3 D- x- [) X0 \" ]
    stop; M8 v' s% Y2 |( M! W- P" h$ |
  ]
) q9 d# i" W9 V
6 o( O% ]0 r) B& a5 s6 z  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color9 k6 B0 I7 {: f# k  z! I  p
  crt num-cars
3 n1 J! g! c9 Q8 ]  [
! A0 L& W6 t' t( l' R    setup-cars) l" S- `. b; J0 N' u
    set-car-color
) o$ a7 r) o. R0 n0 U4 v    record-data
6 H/ p/ O  ]3 I: Z  ]1 a/ {, Y5 Q% l; o% w- p' j8 c4 B+ p
8 T' M( z6 K4 X, o
  ;; give the turtles an initial speed6 w% q1 V' z7 r. I0 A- ^
  ask turtles [ set-car-speed ]  @0 [0 R. }3 F2 j3 I( B, z
+ Y: g7 x! v7 T  @
  reset-ticks
! @/ r3 `0 B8 @end
. b/ a% L6 s' l* N. p3 {
) G( }8 E- F9 y& E/ P;; Initialize the global variables to appropriate values! n! J+ v5 I5 r% Z& l. C: C0 i* m
to setup-globals
* v+ V6 c  @/ l0 q  set current-light nobody ;; just for now, since there are no lights yet8 r, K8 K4 _7 S
  set phase 0
) g) F% j2 L4 V1 S  set num-cars-stopped 0( v% B: i( j0 U
  set grid-x-inc world-width / grid-size-x; |5 t6 U) |) O3 p2 A- j% a, V
  set grid-y-inc world-height / grid-size-y
* P' Y1 i8 g+ A7 Y4 ^
2 M3 v1 F. H& E8 C, Y8 m  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
: G( E7 y$ c; }, e: V' s* e  set acceleration 0.099  L/ s3 h8 E: V. i
end
8 w' h+ }$ P$ h2 L3 L  }2 ?% I. r8 ?# ?4 t3 \( B1 R7 `, |9 A
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,% s+ V2 X2 R/ d: T
;; and initialize the traffic lights to one setting
/ R: t1 h% r. G- ?7 D) {0 tto setup-patches* t9 p& G) L' o! W
  ;; initialize the patch-owned variables and color the patches to a base-color
$ P9 N/ q# B" ^- G# j  ask patches
/ a$ l5 }$ q: |8 H, `9 \  [; E8 N# t: Q1 `5 V
    set intersection? false+ a4 {3 E: J2 g1 r1 V( p
    set auto? false! s) B  L; \) m# D2 u/ j' I
    set green-light-up? true
$ a6 |) n: C5 Y    set my-row -1% _% v" Y  R! J/ h
    set my-column -1% T6 v! @3 h2 F- ]" a
    set my-phase -1/ _  e- O/ Y5 Y$ S; b0 f8 m
    set pcolor brown + 39 V# E% D. }$ r" P$ t$ r
  ]
) u% y0 C- F5 n. N- e; Y7 W2 B  Q" a
  ;; initialize the global variables that hold patch agentsets* G2 v1 P; N3 d
  set roads patches with$ S! R7 L* O' @4 O4 k. r/ ^
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* W( d. h/ L5 o( z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# ^( t! s- b# _  {) {+ y4 Z  set intersections roads with& `7 ^5 [8 w( ]* S$ o5 F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and- N2 x5 V2 d: V% z! j
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 n" d7 Q: K/ b& L3 n; P1 n6 R% S7 k3 ]4 j$ {, v1 w
  ask roads [ set pcolor white ]
( Y5 s. G: f" T7 `$ P# _    setup-intersections
2 j( {, \! e8 N( L# V5 Wend
6 G# g6 N6 k$ i$ ]其中定义道路的句子,如下所示,是什么意思啊?
  |5 _  b# j+ J8 @" H% o set roads patches with, k4 \) z/ |7 M2 y0 p. G
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ o4 @4 u/ I4 w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. F% r3 R' \- U8 N
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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