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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 q, C$ u; U0 a1 o6 Q( l- L% B
netlogo自带的social science--traffic grid这一例子当中,0 [, ~2 V0 i+ ?/ d
globals
) `+ u/ q$ F, B' g# E+ i. Q  Q[- v* p) X9 V! b7 z: ?8 g, C) [$ m1 q* |
  grid-x-inc               ;; the amount of patches in between two roads in the x direction/ S5 |$ j/ y; ^
  grid-y-inc               ;; the amount of patches in between two roads in the y direction  \4 m2 E& Y2 T1 F' [) I
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if' D: i9 Y- E0 V! w0 l) F: B9 G
                           ;; it is to accelerate or decelerate
5 H0 r  l+ P: h  phase                    ;; keeps track of the phase9 R# {/ D9 g  c, o2 ~
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
9 i. Z) c, @4 N# |  V* e) A2 e  current-light            ;; the currently selected light5 q  q: E1 d9 \% m5 _1 u- M- R
. y# d* p  s, t
  ;; patch agentsets
5 S4 y, V0 R5 `6 v  intersections ;; agentset containing the patches that are intersections
* q0 m% S! @: i( ~, _  roads         ;; agentset containing the patches that are roads0 z$ o9 `1 n1 Y: W/ P* ?
]) w2 c6 @; l5 c0 Y2 o2 h( Q- |) `3 @
. O4 d; z% T. M" S) ~4 c
turtles-own" B. |' m: ], w! W; c/ ?
[4 p! W0 @* {! V6 ~& n. D
  speed     ;; the speed of the turtle
; ^; ?$ T9 C0 v0 @  up-car?   ;; true if the turtle moves downwards and false if it moves to the right1 I7 x% H% ^/ s8 b. U0 j0 k3 ~
  wait-time ;; the amount of time since the last time a turtle has moved6 F; q" _* j/ L/ f) u
]7 k0 w  s; R5 V/ E

0 [; R- [+ S. ?patches-own
0 s+ j$ o" c9 O2 g[! |' W3 _2 o; Z/ ^: ?8 f
  intersection?   ;; true if the patch is at the intersection of two roads
+ d" [% M+ f% e5 T% V  green-light-up? ;; true if the green light is above the intersection.  otherwise, false./ G+ m  t6 r: \! J# N. u9 ^- ^9 g
                  ;; false for a non-intersection patches.; M4 e* C1 r0 W4 ]: {# ~
  my-row          ;; the row of the intersection counting from the upper left corner of the
4 Z; U& X  m- m  j, W. C6 x" _                  ;; world.  -1 for non-intersection patches.) C# B3 u; A2 Q  T! J: A
  my-column       ;; the column of the intersection counting from the upper left corner of the2 s4 U, t6 A8 i: U- A4 M
                  ;; world.  -1 for non-intersection patches.6 R  s% u9 D  l
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.+ v1 H  @  b8 h/ K7 l$ Q# d
  auto?           ;; whether or not this intersection will switch automatically.
  v7 W$ d7 Y, u( j                  ;; false for non-intersection patches.- z: u* l" \9 C) Q# ?+ Z$ F# t1 e
]- ~6 b7 {# B7 l3 a' w, N4 J
7 V5 ]/ n$ {( z( c& [' P

/ J/ E8 C, U+ r- {$ d;;;;;;;;;;;;;;;;;;;;;;; J9 I. g: M! E; ], l% ?/ y  p
;; Setup Procedures ;;7 f: y" L4 D1 x. I
;;;;;;;;;;;;;;;;;;;;;;
8 k% Q0 e3 k/ k$ F$ k* z2 s0 x7 C& r& P
;; Initialize the display by giving the global and patch variables initial values.
9 @6 G# `( A2 s8 Q! q( F;; Create num-cars of turtles if there are enough road patches for one turtle to8 H) ?7 x5 w. V( _  ?
;; be created per road patch. Set up the plots.5 m2 G9 O2 ]+ x5 Q+ B
to setup
0 _$ t% y) V) J2 u  ca" `9 o" \6 n3 D; K, w5 Z7 `6 g
  setup-globals' c, {7 _7 Y8 S- O8 b* S" v' g3 G

; a, f# E7 Z; R0 j  A1 Z  ;; First we ask the patches to draw themselves and set up a few variables
7 ?( u$ B5 U' w: q, |1 x  setup-patches/ h! J- L2 O6 v+ ]2 H
  make-current one-of intersections
6 t9 F9 W/ n; e2 j  label-current7 t2 J  _) z( L
7 o8 P& V* h% d
  set-default-shape turtles "car"
6 T3 b2 N5 B: x% }! N0 p' O6 L2 Y1 n8 @( v8 L8 N# ~: Q+ O+ C
  if (num-cars > count roads)
- P( k3 Y+ ]( |* I8 U/ j0 ?  [
  w5 s* {$ K4 E+ _    user-message (word "There are too many cars for the amount of "3 ?3 H+ R/ U& K' g% A5 S! Z9 u! E
                       "road.  Either increase the amount of roads ": f% f9 T) G! X1 J/ Q- X
                       "by increasing the GRID-SIZE-X or "
2 b. K; s% _) G+ j                       "GRID-SIZE-Y sliders, or decrease the "
$ R. K* i  j% J2 j/ {2 p0 y5 a                       "number of cars by lowering the NUMBER slider.\n"6 Y$ G7 m( E0 X; `& ?( E  [
                       "The setup has stopped.")
  x0 @* G4 G) l6 R/ _. }    stop
8 `- p; W1 x' Q' b7 Z& F  ]* c# }" ?4 F' p6 Z  v- v
! G# P0 d/ |* A
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
( G2 p1 [+ g* ?' k. |  crt num-cars+ l$ l% ^& c$ F
  [/ E( k, |# f$ U0 R/ m. g
    setup-cars+ {6 x( h# X( V% w1 C
    set-car-color8 ]: k& ^! b7 @$ z6 v8 p0 J
    record-data
6 w& k! Z% s' D) d  ]
5 N5 J) H3 g' [- Z$ |  x+ h6 h/ G, R4 M& [6 W, O- K4 @
  ;; give the turtles an initial speed
% B- t, U2 P3 C8 H  ask turtles [ set-car-speed ]6 u! ~. R; C0 I
, n/ ~/ a" b1 }  l% S
  reset-ticks
! E# I8 F1 ?& d1 k& zend
. R8 g: w2 B- \. D' c* G! Z. w
# X5 d5 H6 t1 q  P8 r;; Initialize the global variables to appropriate values
, u6 d1 y. a6 g+ M, |) U6 W/ d) Qto setup-globals
1 J, Q2 `) @+ j4 n  A5 S  set current-light nobody ;; just for now, since there are no lights yet
# r& C0 \, `  P/ v  set phase 0
* G) m5 A- S+ l% a/ B- ]' |, ]  set num-cars-stopped 0+ J" A: @$ I2 E/ g$ @' j
  set grid-x-inc world-width / grid-size-x! N+ n5 O3 a2 i  _* m+ q4 W: c  ^
  set grid-y-inc world-height / grid-size-y
8 g/ N. g+ v5 c4 S1 T6 h: D6 R% \5 I" g. h  ^* z* c
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
; v9 j% N3 }8 _: c# a  set acceleration 0.099
; \9 h# A" X6 ?0 iend
& F2 B* W* J1 s) i$ f6 ~4 Q8 O: X+ }
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,$ {7 L. j9 m* t1 {/ n5 [& s, X  E' _
;; and initialize the traffic lights to one setting
# |8 L  v! e3 f9 K- z' [to setup-patches% b& r/ [" q1 i! L; |
  ;; initialize the patch-owned variables and color the patches to a base-color! c- x( e) O$ n' Z5 S- Q% Z
  ask patches
; _. v9 i- f& q. M/ b  P+ U  [
" _8 i1 o! B, M% z3 A    set intersection? false' s& H7 E. y) K, I: a, s
    set auto? false* E% K7 t9 y) |$ g) R/ v" f, F( @: }
    set green-light-up? true
( G% q2 j6 C- a& x/ P    set my-row -1( W4 G# D$ Z! k& Y, Q. Z
    set my-column -1
+ I# ^- a5 c9 i& M5 D, Z    set my-phase -11 c2 z9 q) J8 u7 a4 R9 x
    set pcolor brown + 3
& W8 O# w& |  b" s( p0 j4 L5 U7 M  ]5 d. w( O: W  x4 S! y3 d

+ d) m- h0 K% C) N  ;; initialize the global variables that hold patch agentsets
& B9 M+ e, A: ~+ V( ^# l) y0 _  set roads patches with, F- U4 o2 V; H! |+ q+ T/ k
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 X3 q0 G" e0 V4 {/ C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 z2 k8 N) p( v" o/ T9 m0 N  set intersections roads with+ q* J/ g, ^. t4 c- G+ `$ J+ ?4 P1 ?
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and: [0 Z2 y" t( _, r2 T
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ U6 @9 d! e+ ]2 U5 u  u

# r2 z* V3 D, K: v/ T9 i$ c  ask roads [ set pcolor white ]& M& S) d3 L; C/ X7 f
    setup-intersections+ o) k4 X; N/ z* P2 A
end
1 }, X% D! V! O, P" I7 E+ |. {' Q1 v2 _其中定义道路的句子,如下所示,是什么意思啊?, J8 ?* q/ Z6 m6 V# Z
set roads patches with
6 ^; g, T, z: G. m4 A4 ~    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 l  Z# p; R0 M+ s3 p
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; V/ o" K# K" x1 U# v" [! `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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