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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。
1 [' C+ o1 g4 S) m& H8 `6 Snetlogo自带的social science--traffic grid这一例子当中,6 _4 k' b# N( S, {: D) D% G
globals
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0 a( k( p3 }$ w9 T  grid-x-inc               ;; the amount of patches in between two roads in the x direction" G" a+ H9 J1 A% u1 k/ x. E
  grid-y-inc               ;; the amount of patches in between two roads in the y direction+ h( ]( E9 v0 U5 P2 ^
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if) B+ U, a0 r* ]# _
                           ;; it is to accelerate or decelerate8 ~  X, E$ w% k* y! ~
  phase                    ;; keeps track of the phase; v. E; M9 m9 v7 ~- j) [/ d
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure5 ^; u" k- J) a4 h' p$ \8 S5 d
  current-light            ;; the currently selected light
, A3 N3 _5 \0 |" o0 ~! V: J. Z1 d: [) [4 F2 R" C0 L
  ;; patch agentsets4 {: u5 c$ i( U% |) V; B$ }
  intersections ;; agentset containing the patches that are intersections4 V6 g; U+ [+ F& o9 J+ k6 G$ N7 r
  roads         ;; agentset containing the patches that are roads
) d1 L5 U+ d! `1 q4 u) s0 H]
( Y  v* ^- Q+ m3 @' L1 F8 g
0 i) [7 c; c+ A! }' a$ [turtles-own
4 G2 C5 O7 n$ [1 l[* I. Y% t) M8 q) x0 z: O# U5 o$ C
  speed     ;; the speed of the turtle! b) A" \5 [  ]/ \( F
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
- E6 Z& q7 _# M+ G  wait-time ;; the amount of time since the last time a turtle has moved
: P& A! n% A' |& N2 h2 y]& H3 E$ R- i5 s+ p: T0 _

) e8 K( w6 Q! D. A; H: Dpatches-own
2 i0 s  o: S, d! F6 d$ k[8 t8 L$ i* u3 b# t4 S
  intersection?   ;; true if the patch is at the intersection of two roads, P2 x" T; s0 |
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
: ^5 q8 T3 H) z0 a4 L- c5 y                  ;; false for a non-intersection patches./ l- f" Y* w, y+ Z
  my-row          ;; the row of the intersection counting from the upper left corner of the- k" H+ i0 P, _
                  ;; world.  -1 for non-intersection patches.
  G9 x/ ?# v5 G1 K2 U  ?7 ^1 O  my-column       ;; the column of the intersection counting from the upper left corner of the$ r1 C: ?. D+ F: W% O" x
                  ;; world.  -1 for non-intersection patches.
) D# [8 \* R6 E  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
% Y+ o0 t# u0 ~' Q5 J) i* y: I* E. I  T  auto?           ;; whether or not this intersection will switch automatically.
+ l; W" H) R4 \& A1 f9 o                  ;; false for non-intersection patches.# M( _# I: Z3 e$ }# y
]
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* \  S. N- V1 q& [9 e;;;;;;;;;;;;;;;;;;;;;;5 m4 B8 }1 s1 ~4 W+ h- p
;; Setup Procedures ;;$ d7 w0 H& m. u$ N  N3 I$ y
;;;;;;;;;;;;;;;;;;;;;;
* Z$ o3 U9 f% V* N# t
  u1 F6 Y) p+ P) R0 H- h1 c;; Initialize the display by giving the global and patch variables initial values.$ O  ^2 _* V' K( @+ c/ R7 O
;; Create num-cars of turtles if there are enough road patches for one turtle to
  W) z. H/ w6 l4 r' |+ |;; be created per road patch. Set up the plots.5 P- f6 L' c# o* y% \$ ~
to setup
0 W+ C3 h+ C9 c! b: V6 Z  ca. f4 O8 v1 f$ `7 d; H; Y) [7 O1 P
  setup-globals
: J. {$ P3 Z: @8 `; o) S
* g; [" y. p1 q. ?  ;; First we ask the patches to draw themselves and set up a few variables) e# c5 H, m" S
  setup-patches
! B% [) c2 A, Y+ C( K& P  make-current one-of intersections3 g4 u. o2 L, k
  label-current
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  set-default-shape turtles "car"
% h+ l3 G3 q6 s- L" A' d4 ]
- J% v& w+ E9 x+ e! v  if (num-cars > count roads)
; p9 A) w( ]  V; {5 ^# D  [. S- I; Q: Y" r: W1 I
    user-message (word "There are too many cars for the amount of "  q1 J, l' x& ~0 e1 H
                       "road.  Either increase the amount of roads "' U1 ?  t, B! J: N) O
                       "by increasing the GRID-SIZE-X or "5 D" g+ g( Z- L& O
                       "GRID-SIZE-Y sliders, or decrease the ") c  I- @" V0 f1 `6 P" `
                       "number of cars by lowering the NUMBER slider.\n"
: [5 y9 `, a6 Z4 w  a) e. W                       "The setup has stopped.")
; ]' a! N( ^. n    stop: m7 x6 z6 A: |& @
  ]
  j5 y1 x0 N) I2 |
6 |& Z) u4 L% z$ w  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
& j  I; v! ~, s  crt num-cars/ O7 u$ d" V" j# i
  [& @+ b% ?# Q. I9 N: s2 \: Y
    setup-cars# {+ @$ b. s* J) `
    set-car-color6 u: o2 h) A5 N; X0 o
    record-data
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2 B/ s! i: `# m/ T. @( \% J# t+ I  k/ p1 f2 ~2 j
  ;; give the turtles an initial speed# e; [+ L; L! ~& x, y0 n; G5 ?- W
  ask turtles [ set-car-speed ]& J8 v* H" s$ I* _: S2 m  _. R
9 A2 G# X: Z, F9 \- p* R# {
  reset-ticks" f0 A- W) y) F# e
end9 _9 k1 a! P9 c* c  c$ |+ F
& y  N5 r6 e' Z
;; Initialize the global variables to appropriate values
) Y- l7 H3 E: ^+ T, @to setup-globals: \6 ~" n* A* D; k, s
  set current-light nobody ;; just for now, since there are no lights yet# P) e4 X  G8 h4 t3 i  L! `
  set phase 0
) B- Y, F" [  O6 w  a' }8 K% O/ _/ T, g  set num-cars-stopped 02 H$ T2 R8 ~. L/ I; \* m
  set grid-x-inc world-width / grid-size-x+ |$ p/ I: J2 U8 Y1 Y# F9 u/ q
  set grid-y-inc world-height / grid-size-y3 g1 E# m" [+ R4 |% z/ ^
7 p- K# V6 W" t. [' z
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
* E$ i1 t9 v; E8 P# N  set acceleration 0.0997 D# I! g* S# D& k3 z9 [/ ~
end
  C3 Q3 ^- w# \' h, h
. U; o* I- w* ?0 n0 m2 b;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
, `2 }: u9 m; r* u3 i. j;; and initialize the traffic lights to one setting7 ]4 g5 D* Z) D, P; |' C& y. o
to setup-patches- x4 B/ n8 `$ ?& C& j6 Y
  ;; initialize the patch-owned variables and color the patches to a base-color
; w) V3 Z, e7 [; F  ask patches  \# o1 d' o+ K. K0 Z
  [. _9 D/ c+ u3 s# h
    set intersection? false
+ H: _3 M' _. S3 w- ^( Z, w    set auto? false3 d3 [5 o7 G4 ]% l1 m  S) \
    set green-light-up? true) P" Z' f$ [) B$ t, \* B: y
    set my-row -1
4 N" O) m* r& y8 _    set my-column -1
  d' d3 e6 ]. r& z3 g    set my-phase -1% ?* M4 Z2 m" D
    set pcolor brown + 3
! Z, b9 I# ?4 g' H  ]* D1 x+ B# ^6 n! Q# B1 C

, d5 n9 T! A' G# ^2 O  ;; initialize the global variables that hold patch agentsets
' D+ K* U( F: G( p+ c* i  set roads patches with
  m: X; _# S) s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  ?. [. D3 P4 o9 e$ w+ |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 A5 ]5 }) z( k: a# N- P
  set intersections roads with
9 v; n, j/ R' _9 Z: ]! f    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
0 ]( o8 F4 N' Q, o; D    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 X( W1 W1 q% o
1 y% i' |& m& q& ]  ask roads [ set pcolor white ]
# o5 A5 @  T% h6 B  G6 [% B, d    setup-intersections/ Y+ G9 m6 H1 I( f  C
end1 e8 k$ S; P& H* R4 P. Y* X$ m  a
其中定义道路的句子,如下所示,是什么意思啊?
* X+ G. c+ T! _+ j# f set roads patches with
6 w' o  U5 j" h4 o    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- f1 e: U1 d& N0 G' e# t& r
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& {) h7 i9 S# x& y* G0 W# C+ Y
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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