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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。
# d+ E* i8 B" t% ^9 vnetlogo自带的social science--traffic grid这一例子当中,$ P! h+ R* Z( M. ?
globals0 `7 x& E) }4 a6 m6 [, i+ k
[
! z! t% k/ N- E) z9 _6 q  grid-x-inc               ;; the amount of patches in between two roads in the x direction& S! I; v6 U2 d  m! V. F) c
  grid-y-inc               ;; the amount of patches in between two roads in the y direction( T$ c2 e+ b% i( A5 c0 v5 D" z4 p) T: E/ G
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if3 L2 x' B3 m/ T9 s) A
                           ;; it is to accelerate or decelerate
) A# R% I1 O4 x6 C& {. Q! j9 j! o  phase                    ;; keeps track of the phase5 F2 \8 G+ \8 R. R- S# o
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure! ^  X' [! k7 Q: s6 B) z
  current-light            ;; the currently selected light5 |& Q1 q  ~# S

# D$ o3 M9 f5 }; W& ~& S- i  ;; patch agentsets
) F, [7 z. Z, R  intersections ;; agentset containing the patches that are intersections
+ r/ W/ }$ m$ E" m1 L$ y  roads         ;; agentset containing the patches that are roads# c- U$ L/ s$ F) Q3 Z
]6 M4 |( G  O6 l: o
9 y2 U% N6 ?( m) K
turtles-own
. ]: V- s6 _3 j[
9 f# N( u8 V0 i; X5 }  speed     ;; the speed of the turtle
0 r3 ^. B* L4 v  up-car?   ;; true if the turtle moves downwards and false if it moves to the right3 p+ u% e2 p$ H. q6 I; ?- P: b* h
  wait-time ;; the amount of time since the last time a turtle has moved: D& C3 |2 }& X0 |+ H9 v
]! B* |6 {( l" Z5 D6 _! Z
) I) |) N* C+ r0 E4 m
patches-own# o% |. A1 f/ A5 i
[& _3 L$ J& u5 X* Q5 f5 @; i
  intersection?   ;; true if the patch is at the intersection of two roads$ O- @& X6 u$ I
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.* @5 a; P9 P* Y# s; `) i# Y
                  ;; false for a non-intersection patches.' s  L0 U) L$ n  i
  my-row          ;; the row of the intersection counting from the upper left corner of the) F$ ~6 D2 M* n
                  ;; world.  -1 for non-intersection patches.
. U  P3 D" j' Q  i5 x  Q6 z1 I  my-column       ;; the column of the intersection counting from the upper left corner of the" t6 g2 }' f6 V/ z  H! U4 H" l% s& r
                  ;; world.  -1 for non-intersection patches.+ w5 ]- P  @* g5 x5 g6 O: r
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.$ v5 N. s5 {: D% f! A, Z( f; T. h
  auto?           ;; whether or not this intersection will switch automatically.- }( q! v4 p3 m$ `( ^9 Y
                  ;; false for non-intersection patches.* a$ O( Y6 g: |5 j
]
( V& _; P& E( b6 m# e& t' B% _
' F% j1 F+ j, t+ I  n; |5 w- E3 J6 [4 F0 T7 i1 {+ C
;;;;;;;;;;;;;;;;;;;;;;
8 ?3 e0 v7 A; ~, }# s;; Setup Procedures ;;& w$ Q# s) D$ W) @& b+ c
;;;;;;;;;;;;;;;;;;;;;;7 I( ~4 c0 P7 {. D
% W" V) u! c' w9 e+ j
;; Initialize the display by giving the global and patch variables initial values.
& L* l6 R# F$ l5 R% v/ w; g- E;; Create num-cars of turtles if there are enough road patches for one turtle to
' F6 E! \3 I( F. e, s9 |;; be created per road patch. Set up the plots.
$ Y1 ]( J. i* H! A5 vto setup* b4 f7 J4 o8 X: B0 ^* z
  ca& F# ~; s" ]' d/ @$ s
  setup-globals" Q  H6 P* X& R$ O% I

- D* f+ D% E, \* T2 T( W, I  ;; First we ask the patches to draw themselves and set up a few variables4 z7 e: B) Z' B
  setup-patches
: Z% J  t) E) g8 \+ V- ]  make-current one-of intersections
1 o2 ~8 ?, W& N  label-current
+ C: ?& z5 `; [' }
5 X# V+ x% [& f% z2 K  set-default-shape turtles "car"
, `* @% n3 v, U, t, T$ R
6 y' g" x* R# l3 ?. a/ T  if (num-cars > count roads)& U, `! R6 d& ^: d% {. `( J
  [
& u! p2 s# d! n- F    user-message (word "There are too many cars for the amount of "
+ l, o' `2 i4 C9 \6 j$ Y" b                       "road.  Either increase the amount of roads "- P3 f8 E: k) y3 `- M
                       "by increasing the GRID-SIZE-X or "
% b+ y# x' A7 ?3 l                       "GRID-SIZE-Y sliders, or decrease the "
: ^- R$ }" ^: B, E$ X" s                       "number of cars by lowering the NUMBER slider.\n"* t8 j+ J4 g! B- L% u7 y* W, [
                       "The setup has stopped.")+ S  C& D8 B6 }) f8 q' x6 b
    stop6 p) F5 [3 l9 C5 Y$ d
  ]( f" D) x: p8 s: I+ j0 {* }; L

) ]7 Y" u4 G1 X  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color: Y- c% W" }' {5 {9 U5 ]
  crt num-cars+ h$ J8 ?# x. t
  [
$ ~( G8 N5 J: K% w0 A    setup-cars
+ Y2 ]+ U. @! `) O+ [1 X+ F4 A    set-car-color
3 w# s. j  x6 J    record-data- v% b) j. ]( ~- d/ G
  ]+ f9 I/ M& r; m$ u" @5 {
  v5 B+ d1 N, L( N
  ;; give the turtles an initial speed6 M# Y  _4 O& H
  ask turtles [ set-car-speed ]* P  n* z4 D, D, v: ?; f
0 e6 C. G, R3 D4 x
  reset-ticks0 y0 m& b4 L% M
end* Q; R$ B% K1 j
5 \1 P: V! T- A) `
;; Initialize the global variables to appropriate values
( T4 a  g" P% Rto setup-globals
/ m; {! N; y4 F  set current-light nobody ;; just for now, since there are no lights yet
) |. }; A, p7 |! `  set phase 0) O( K- r: V/ @% H" t3 g
  set num-cars-stopped 0% V1 \: r! l( L! ]
  set grid-x-inc world-width / grid-size-x  C; j  s  b" p  S0 E  e1 }- S6 @
  set grid-y-inc world-height / grid-size-y2 R" F" g, n  g1 J! I

9 c  l( y& r: D( U& B  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary! ^5 f! Z" z' ?; v
  set acceleration 0.099
( [! D) [# @( p0 Nend
6 U7 L( U- T% y  N3 z5 L
6 n0 a( ~2 K5 z;; Make the patches have appropriate colors, set up the roads and intersections agentsets,/ B/ n2 E- a6 ?0 A& F5 f( S, V/ v
;; and initialize the traffic lights to one setting; o: R4 E  E: U: q) V3 |
to setup-patches
7 `+ c" w8 Z7 r' _5 F  ;; initialize the patch-owned variables and color the patches to a base-color
, C+ Z! ^. `3 w' b  ask patches  j& d" F9 r- ^. _! p+ g
  [2 M  Z# j$ m% i; t8 k& E
    set intersection? false7 [/ q1 E- E" J; D- r9 j+ I- X
    set auto? false
- o% K7 w# u6 l" G% Z    set green-light-up? true
3 Q# l) j0 n) j+ V$ Z    set my-row -1
' g. Q! M7 M! u2 Z    set my-column -1- w0 [! n8 H% I. |
    set my-phase -1
# b6 R& x, \' Y* e    set pcolor brown + 3
0 k9 Y1 B9 e# R4 N: E' n  ]) H) X$ A' y: {1 L2 s

! C0 j3 m6 y' S  ;; initialize the global variables that hold patch agentsets3 W6 ^7 o# B9 }$ A& {  {4 q  s
  set roads patches with
* m8 }% o; |( ~6 g* L4 \    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) W% W. t! X# H8 ]    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 ^$ N7 O4 p1 u. b  set intersections roads with
- T# N4 p# O; H+ k& ?: C    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
" M& t  T/ f. a$ y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  F1 z2 s1 M7 p8 E1 M
7 j3 g+ N' p# t7 B0 m, O! a  ask roads [ set pcolor white ]% k5 L4 A, O9 H1 `/ ]6 M
    setup-intersections7 k; \8 f6 A: i
end; B6 \/ m7 G, r4 ?, x) n( e
其中定义道路的句子,如下所示,是什么意思啊?- i. X" X: X" F1 ], u
set roads patches with
' ?. `/ K! Z. F4 x2 @    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 Y9 o) N& w) P) B7 N1 ]) |
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ J' m! f& o# t  E! m
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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