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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。
6 I3 J" W3 g% F' znetlogo自带的social science--traffic grid这一例子当中,; P% G8 }3 i+ s& c$ E
globals
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  grid-x-inc               ;; the amount of patches in between two roads in the x direction5 r4 w3 V. L5 E) V
  grid-y-inc               ;; the amount of patches in between two roads in the y direction- H8 G6 B: E! L+ g
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if$ s$ F# D. }/ o6 k
                           ;; it is to accelerate or decelerate  p- n. d; C2 V9 z6 J- }
  phase                    ;; keeps track of the phase
# j4 Q$ Q) t" a; D% a( Y  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
4 x/ z' w0 s6 w$ ^2 p  current-light            ;; the currently selected light- q1 r1 r9 [- Z8 J7 }

/ X% p7 A7 v" O& S( R  ;; patch agentsets. H  g, J' S! I5 _8 V% w4 Z
  intersections ;; agentset containing the patches that are intersections- t% [+ D2 n" k+ x; t
  roads         ;; agentset containing the patches that are roads
1 q) H1 |2 c; y- n]9 M' _# E7 s5 E

2 F: q0 R, w8 Z& g4 C7 d/ Y/ Yturtles-own0 c5 {" J7 }0 O; z
[+ u2 a; _2 Y6 k
  speed     ;; the speed of the turtle
+ }* i* S' o  C- L: O- b* s) ]( c* r, E  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
; T1 T0 j% ?5 U  wait-time ;; the amount of time since the last time a turtle has moved
7 X2 E- P* V+ {/ _( M% q) J]
9 C+ H* w3 i* P3 `) H
; s+ E$ ~& X$ l+ i( Vpatches-own
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  intersection?   ;; true if the patch is at the intersection of two roads  o0 P, j) h5 a! K
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.3 c9 t- ?! i1 l/ o+ x" j4 r' c8 n
                  ;; false for a non-intersection patches.  X* o9 ^' H; u* ~/ \
  my-row          ;; the row of the intersection counting from the upper left corner of the
' k2 {; U6 B1 Z, Z# ^+ g                  ;; world.  -1 for non-intersection patches.
4 v, M" i, d: S  \9 C/ o9 d- a  my-column       ;; the column of the intersection counting from the upper left corner of the4 M. s9 G) [& N1 ~0 A
                  ;; world.  -1 for non-intersection patches.
# |" u3 d" X- c* _9 i  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.2 X( U- e$ T  P
  auto?           ;; whether or not this intersection will switch automatically.
1 u/ w& S4 Z) h5 Q$ c3 ^                  ;; false for non-intersection patches.
* m! Z& E3 B5 o! T+ I]% M" x) r/ ?) Z9 v6 x& o

0 e% v0 B1 o6 J" n' ^
2 @9 [. s' @& c/ E' p# f/ a  h;;;;;;;;;;;;;;;;;;;;;;
/ E5 F2 m8 a) B;; Setup Procedures ;;
' g( H4 n# p5 F;;;;;;;;;;;;;;;;;;;;;;
) O* i6 ^* G6 d( `3 i) ^
5 q, s9 p! L! d, @" D;; Initialize the display by giving the global and patch variables initial values.( ]6 v$ H5 r. p6 B2 u
;; Create num-cars of turtles if there are enough road patches for one turtle to1 e7 \2 C; l/ a! r7 w& b
;; be created per road patch. Set up the plots.
  j" G# L# A7 E  \* Uto setup
( k( K# G; x& E- G  ca
. D6 U2 z7 R6 U8 m* W+ Y3 Z0 i2 R  setup-globals, ?5 n7 r( h) p2 @1 G
: P& K! ~0 u0 v/ \$ O0 Z
  ;; First we ask the patches to draw themselves and set up a few variables$ s7 Q3 ^% J5 i7 B5 T
  setup-patches/ d7 V( U" {5 u# J$ T9 z6 W& K% B
  make-current one-of intersections
; h0 W$ S5 C9 A2 H  label-current
/ f; j5 ?- Y# x* H& D% Z/ v: S% T; N  M4 \  u& M/ C
  set-default-shape turtles "car"% y* Z. a. E  ~; N4 A# A5 S

& C8 J2 R3 B7 C9 a3 w4 r  if (num-cars > count roads)$ m$ Q2 k. ]5 l. ^$ T" a
  [5 L+ b* n& [( C, M% k. P" t
    user-message (word "There are too many cars for the amount of "8 C# T4 d4 ^7 Z9 [: G. ?- M! J
                       "road.  Either increase the amount of roads "
" H* g$ x8 x# @7 X* O                       "by increasing the GRID-SIZE-X or "
3 _* Y. S7 t6 U# c; {* t' P                       "GRID-SIZE-Y sliders, or decrease the "9 A. i# G- C7 N
                       "number of cars by lowering the NUMBER slider.\n"& f% a3 y2 U" k% J3 B( j
                       "The setup has stopped.")- {' ]; W+ ?3 n  p  d
    stop( h7 S, u! m: ?1 Z+ X# i
  ]
3 a- X7 e; N. h5 d8 L) o. Z! C* u3 i+ E* C# ^, {2 O/ s
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color. s, y+ q+ l. t
  crt num-cars% y0 o# C- U/ T* ^
  [) D4 ]8 q7 k4 W* a+ R
    setup-cars7 X4 }& M2 o, ]
    set-car-color5 L3 H$ C9 D; f7 a8 t% o2 W) b  J
    record-data+ |) A" z' V, y; ~% J
  ]
3 y5 T5 H( j, p. V3 `/ f1 h0 V- c9 y- t  A; h
  ;; give the turtles an initial speed8 ?% _" }/ l) Z! U. y* G
  ask turtles [ set-car-speed ]: I" g$ T8 `9 C2 _* H% ^* H! a+ r

# z' @# r* }5 Z. J' F  reset-ticks
! \; w4 B$ k; S" `) Gend  [, y& X/ I, r1 I+ h! x

+ [6 Q9 W0 k6 p% Z3 {;; Initialize the global variables to appropriate values( }6 U' [6 H" K. F; l
to setup-globals
  r6 ~* d* g9 ~3 w& V  set current-light nobody ;; just for now, since there are no lights yet3 Q8 s) ^  l& ?- H/ I4 r; I+ [
  set phase 0
' o) L5 ^- k- y# ~$ g$ _  set num-cars-stopped 0( p/ L+ S$ t/ \( B9 s* w
  set grid-x-inc world-width / grid-size-x  n- G  N5 J3 ^5 W0 ]1 H) w) q8 Y. ^
  set grid-y-inc world-height / grid-size-y* z, T. N- t, l' Z5 M& N: a
& V9 I  w5 I' F9 V$ N1 `/ |
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary. ^' h  u1 a8 M& @
  set acceleration 0.099% C9 R+ V' B3 t! f8 o5 n
end
  O4 {) x+ v$ Z2 q# Y6 S' T7 w2 \/ Y9 w7 z+ [
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
% i1 F# ^1 J- I0 [  y0 c;; and initialize the traffic lights to one setting
7 f! \. ]) Y+ I8 |to setup-patches. B% v, B" I7 M+ c7 z
  ;; initialize the patch-owned variables and color the patches to a base-color
$ V- u8 _  g1 o- p4 N  ask patches
9 R% M. N8 R* V" J( w2 y# _  [
0 \5 @( t- \# }5 _& q* R+ n0 {0 \  J    set intersection? false
5 H' j/ w% d  {, M4 W0 M    set auto? false
. |# q3 Y5 u( \* m  p    set green-light-up? true2 Q% R, d. h/ P: G# L+ C
    set my-row -1
' Z5 W' Z* h0 W$ Z. x    set my-column -1
4 K4 N8 L6 _& h% E( j2 D! ?; ^. i    set my-phase -1
3 e" k) N. `$ G, x. B  K" f    set pcolor brown + 31 L* Z/ o' ?! U. V% M+ F& u
  ]/ k" I7 s& _/ A( u. E2 f/ N# Z
6 Z, f3 \) I2 c% D
  ;; initialize the global variables that hold patch agentsets
5 x: e% c! z- Q1 ?0 _3 `' p( }  set roads patches with
2 v- B/ w% l* G    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 `+ {: x$ Q. s6 B    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  U# g! a/ C6 A# d8 A$ ^
  set intersections roads with' W6 h, D# t9 k+ ?% j
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
) V, h! T6 C$ e% l& k! g0 j9 N    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% p: S5 z! Z4 ?3 Q3 Y8 d" g
6 }5 G* w2 C; W* d
  ask roads [ set pcolor white ]
1 z: d% V4 f# w    setup-intersections( _2 b0 v; y7 `7 I
end
& M4 p1 g6 p( e) y4 m其中定义道路的句子,如下所示,是什么意思啊?/ [4 R5 X# m3 y; n0 r
set roads patches with. i. ~' B* ^  L5 Z' R5 T  [
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ y+ t6 f1 n5 a! ~, q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. W4 Y' c7 E" w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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