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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。2 G9 N) T# v' j/ V# H6 K/ y5 t
netlogo自带的social science--traffic grid这一例子当中,7 h% ^% A  U; v7 B: S4 v2 D* [
globals5 a- i) O1 t) g' k8 h) i3 v
[0 l: u5 v1 k* B( ^; n# q" j
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
! t" @3 K# Y/ v0 ~8 N( o; ?; [6 L  grid-y-inc               ;; the amount of patches in between two roads in the y direction& {- a1 ]6 {* \9 X
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if) l! o0 y9 k$ h8 z- l. m
                           ;; it is to accelerate or decelerate
& T( T5 g9 N: u1 y2 i! Q8 d! f5 J  phase                    ;; keeps track of the phase* H* b- P  ~3 R& f  }6 X
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure7 a6 G+ R: }/ v* e. b/ V
  current-light            ;; the currently selected light5 J. ]) F/ |  O$ H5 @- i  x4 r6 s
. g8 e3 _! B1 D  @& q5 {( I
  ;; patch agentsets
! u- o1 @8 C$ ^  intersections ;; agentset containing the patches that are intersections
4 O$ l% y, }6 O2 h- V/ Z& O2 A1 b  roads         ;; agentset containing the patches that are roads
+ M4 h. n1 r' z% J3 A]
& o0 q$ _: I9 ~" H4 Z; K. a- ~6 u" R8 }1 G# W, ^% @
turtles-own6 q- ]. Z, S& F  D
[
& G) D8 m& v( M* I# Y9 B7 K7 ^$ V! H  speed     ;; the speed of the turtle
. q+ h2 Z1 f8 q7 K  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
5 G, s4 U! p1 Q  wait-time ;; the amount of time since the last time a turtle has moved; `. k' P/ l; p, w" p
]1 m# c( e+ x* i7 t9 i" k
  k% ]  P' P" r" O0 {- g
patches-own4 t% O0 @4 @" q9 j  Y- c! x8 W
[
) f! F8 L& I- z- l7 J  intersection?   ;; true if the patch is at the intersection of two roads
* O, D0 j4 v/ X  H' {2 V$ s; d  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.2 X) \. I/ t5 Y- `
                  ;; false for a non-intersection patches.( S7 b5 K' S" [
  my-row          ;; the row of the intersection counting from the upper left corner of the  X7 c4 e( X3 P
                  ;; world.  -1 for non-intersection patches.
& J: |- F( h. _& }/ F; a  my-column       ;; the column of the intersection counting from the upper left corner of the, Q8 r9 F5 m9 W  A" z9 u
                  ;; world.  -1 for non-intersection patches.
1 s, @& I( |; N5 M/ S. v4 w% u4 k  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.) m  P/ V: e5 B1 R7 H
  auto?           ;; whether or not this intersection will switch automatically.
1 {6 c4 a0 c, M* d                  ;; false for non-intersection patches.
7 u7 [% |. V* E) O8 N% |6 b+ f]
$ Q! t2 e! G; i8 b, y4 N% ?
; a. x- M3 q6 P6 @7 Z
' U7 D! U1 ~5 I. f& _0 s# H& P4 O;;;;;;;;;;;;;;;;;;;;;;. b+ z, T, d; ?! A2 |" I( [
;; Setup Procedures ;;
2 M8 d3 _& R8 X; \% n/ p;;;;;;;;;;;;;;;;;;;;;;3 ?! u: Z5 |, N0 m

! n4 {& V8 [8 r3 q+ O;; Initialize the display by giving the global and patch variables initial values.
+ W- o* ]( Y+ {" V5 e;; Create num-cars of turtles if there are enough road patches for one turtle to/ t1 u+ p& I' l( Y- I3 m
;; be created per road patch. Set up the plots.& M4 [  R% [6 B0 Y
to setup& j0 M* \. x/ R/ I& t5 x
  ca
" |, q4 r; _; d" d  setup-globals. u9 l1 h  W' }

( O- P* o; y8 _. t  ;; First we ask the patches to draw themselves and set up a few variables0 O% _* I, e; y9 I4 _. j7 Q
  setup-patches
' i& d# x6 B& }8 D  make-current one-of intersections' Y. m' {+ O9 ~9 K
  label-current$ F; g. k. ]0 T! m8 \2 O

( y' d- T; |( X0 V) b* C  set-default-shape turtles "car"* }# K5 C+ W: y2 x9 T

, t2 P1 v. ?9 Q& U2 m2 H% m  if (num-cars > count roads)7 \% N5 i  }$ g9 A
  [
' R) v: b: Z- s" M8 u& ]: L% W    user-message (word "There are too many cars for the amount of "3 L1 {7 N( S9 H2 l6 W8 B# n
                       "road.  Either increase the amount of roads ") H: L; b0 p( W5 j& g' P) e
                       "by increasing the GRID-SIZE-X or "
9 c* W& E0 D- }                       "GRID-SIZE-Y sliders, or decrease the "1 v6 U7 y. w! z
                       "number of cars by lowering the NUMBER slider.\n"
! C) k% {7 E$ P                       "The setup has stopped.")
2 w& ]: z9 E8 ~4 P    stop
. J- K/ `4 F2 X, a; l; |9 m# k1 w  ]% _) Q0 Z$ ]+ O  A, U# n
+ p, f- a( `2 _+ a$ M6 j0 ~
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
9 x4 \: `" m: n  crt num-cars
2 u" g) B& T9 q. V' R, V$ K  [
# a) L# b4 H+ L# b& W* P    setup-cars8 R2 D7 ?9 g, m: r+ {, H8 a
    set-car-color
, N: }- u) v: d! J- T    record-data# ^; h* c* O) x, A$ b
  ]8 l/ t# r' t3 P  K! d: F* M5 w
1 b5 @- u& r0 ?
  ;; give the turtles an initial speed4 J9 ]' x) y7 R! Y/ k2 c/ K
  ask turtles [ set-car-speed ]% U1 V9 j# K- c, M

5 e9 w0 [) r$ k  A  S  reset-ticks
9 R) C. s. T( \end
# \# x5 |! }8 W' r, D, N8 \! S5 k# D; `- O! O
;; Initialize the global variables to appropriate values$ h9 D+ T2 m1 I: w5 B
to setup-globals
" T/ T0 h; j( V$ ^( O% @6 G  set current-light nobody ;; just for now, since there are no lights yet
3 a0 U& [0 V4 M  p% f  i  set phase 0' m" e1 G! @$ _1 i. L! |  x4 ^8 K
  set num-cars-stopped 0( W; F. T) j" P4 W$ [$ K. W
  set grid-x-inc world-width / grid-size-x; J1 N; a8 T0 C0 _* l$ T' @4 X
  set grid-y-inc world-height / grid-size-y
7 d3 F1 m- ?8 M4 @3 E
8 l' Y9 r; A; u4 Z: W! C  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary1 m" j" I2 E5 R6 t
  set acceleration 0.099
, {7 ?, c$ j% Q, C' Eend; Q6 |5 F" V1 [, V2 X. y  P; Z

% n0 L0 m1 `* N" }! i$ {;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
" t& {+ J& x# H! k/ |; e' n;; and initialize the traffic lights to one setting
7 ~3 u. N- J/ p1 _* x' i; Tto setup-patches5 H; `2 h5 _& i* @3 f6 {% H% X
  ;; initialize the patch-owned variables and color the patches to a base-color4 k  e2 M- Q" j* d9 S" K, X; D
  ask patches
* O, ]6 Q9 @' u" `  [
1 o; `) Y, @/ F9 H% @; m' s0 a6 {    set intersection? false: ]( W& O: @" m$ M" e1 `$ B
    set auto? false
7 l4 T6 A5 O7 j9 J' E% W0 G    set green-light-up? true
) ^1 S9 Z1 K! R: t3 X    set my-row -1
/ Q$ X5 W5 F2 o& d; H    set my-column -1) |2 i( w; c6 `% q, \
    set my-phase -1
# F, f! T* |* k- }/ |    set pcolor brown + 3
0 ]5 w3 e4 z/ I  ]* U9 m9 o% b9 z& c  V5 p

+ y$ S3 W# h2 U, M' l; C  ;; initialize the global variables that hold patch agentsets
, P0 ?2 c' y6 `; E9 R0 Z( K  set roads patches with
5 r6 T! B; m/ Y/ {) [" B8 s8 D8 Y  `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
/ b9 c  S% X$ n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: a) q. {4 K+ F+ \4 r  t+ u
  set intersections roads with
$ d' z4 t" N7 V0 F1 K; t# s% E' Z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and! c/ r# N( k7 c+ g
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 n0 s7 b- f7 P* y4 _
* i1 Q  F# s9 \1 i& R9 y  ask roads [ set pcolor white ]5 M# `" I6 A- c( g( c( ]) H
    setup-intersections6 s3 M7 x0 |4 p8 {) b4 X
end+ l$ E' ^$ O- n/ g+ U+ D) ?; j
其中定义道路的句子,如下所示,是什么意思啊?
6 g; r5 X- m& B set roads patches with0 G; M# r0 _% `, ?; f0 F/ b
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ @" I& K& R% t' C& P/ R* V( r' n
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  h) E8 |) ]. T4 m% X7 H; w4 r& U
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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