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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 I* I7 j& R- C5 Y2 S  \netlogo自带的social science--traffic grid这一例子当中,4 I: q1 m. B* U0 y: e
globals6 S) \0 _0 `/ [3 B5 ?7 b( j: |
[) u: ^! f# ^) Z, l5 v2 C- I( n9 t
  grid-x-inc               ;; the amount of patches in between two roads in the x direction# P% L. |" i' H
  grid-y-inc               ;; the amount of patches in between two roads in the y direction/ x; A( `$ F  ]* p1 \: b
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
6 u/ C1 E" K% S! O4 G6 S                           ;; it is to accelerate or decelerate
" G, m& _, \0 t) ~$ X4 T( a  phase                    ;; keeps track of the phase
% d1 w( \" `" r* S1 W! B$ b  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure/ z$ [6 p2 [& a4 ?7 X
  current-light            ;; the currently selected light
$ o1 U6 E% j) O' M" q* I/ ^7 Y1 L. n5 d$ r- @* H* Q! f
  ;; patch agentsets* M$ L5 v+ s1 `8 t0 ?3 K
  intersections ;; agentset containing the patches that are intersections
, e3 a) F  z3 J) u- ~8 O$ }  roads         ;; agentset containing the patches that are roads4 }4 q+ g: u& ]  O0 a. T$ G1 `
]
2 {! v6 f% R( D8 H
3 E; e9 z& }1 D# oturtles-own; \5 C3 _5 l6 S5 h5 K
[
% C. n3 Z8 A1 A, M/ N  speed     ;; the speed of the turtle
) l8 c1 c# ^% `* y7 e' s  up-car?   ;; true if the turtle moves downwards and false if it moves to the right6 b: h6 X7 x, A8 ?  z/ y  E6 N9 X: Q+ G
  wait-time ;; the amount of time since the last time a turtle has moved
  ~* G3 g' {: E2 k]
2 R$ i% t6 O) ?% G6 y0 w, v
$ k8 Q* e1 K$ G4 }patches-own
' W9 |4 _. h6 Z! g6 {' i[
; N' C1 n! T. I% n# G' s  intersection?   ;; true if the patch is at the intersection of two roads! P) S8 H+ q! U  z/ u' M& ^
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.; _8 J' ^( a. J4 B
                  ;; false for a non-intersection patches.
! t. C9 Q: s4 k# @  my-row          ;; the row of the intersection counting from the upper left corner of the; r8 `" N; c8 m. B1 ]. I% O
                  ;; world.  -1 for non-intersection patches.
2 p4 @8 {0 `  y4 h+ }) k  my-column       ;; the column of the intersection counting from the upper left corner of the: P2 i, p) X; h+ |( F/ E! y" M/ G
                  ;; world.  -1 for non-intersection patches.
- e# i% _* e, f& j/ h( g8 j0 a  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.5 `7 ^# ]! w2 B- Y
  auto?           ;; whether or not this intersection will switch automatically.
, X- f7 g2 i4 u! F+ g! C: N9 U                  ;; false for non-intersection patches.3 \& y" i( y( o  F/ v# l8 _% z
]
7 s" f, q1 Y) q$ d* |5 u4 m8 M6 X6 @' X) \' X5 n

7 H, f5 S& |6 n9 C  C5 A$ f;;;;;;;;;;;;;;;;;;;;;;6 s4 x  K9 i' a8 Y# }- p: p
;; Setup Procedures ;;
# T. o  q5 M2 J( o& T4 U+ u;;;;;;;;;;;;;;;;;;;;;;
- I1 J/ d0 }7 u0 v: N2 a/ H" ^4 _) W  y2 g
;; Initialize the display by giving the global and patch variables initial values.
' a2 d. Z, F- L- G) i;; Create num-cars of turtles if there are enough road patches for one turtle to4 F* g& v5 c4 @" f7 Y3 o
;; be created per road patch. Set up the plots.. T. m9 L- d% _
to setup( ]" }  `1 ~$ L0 q$ Y0 ^
  ca( A$ R' {: X' b; o2 J6 x' m
  setup-globals
) T# c+ P7 l* K$ g
5 E0 f6 ^* m' P8 |: V7 z. j  ;; First we ask the patches to draw themselves and set up a few variables5 d& ^2 M6 M  T! B0 G
  setup-patches
! o0 v3 t& t" d1 d' T/ v  make-current one-of intersections- e9 |0 f" |: c2 A5 x/ H# _
  label-current4 ?: V# U% P0 i9 K# d$ U0 m
: L( n5 [; Y3 j$ B0 y) p
  set-default-shape turtles "car"" {! d& D9 z2 I& \
  u/ y8 D! H$ O. M
  if (num-cars > count roads)" @, D1 e: K0 k& o& L  `1 n
  [4 l$ R3 a3 Z7 {. g: B; b' Y
    user-message (word "There are too many cars for the amount of "
) t, g% ^8 d% S; s( V                       "road.  Either increase the amount of roads "
4 N0 c  q/ W2 R$ C1 s                       "by increasing the GRID-SIZE-X or "
/ X" c& @* ^" G2 A5 M- v; k                       "GRID-SIZE-Y sliders, or decrease the "
& T# S" h5 t9 ^                       "number of cars by lowering the NUMBER slider.\n"
* ^3 U( Q7 E5 z: ^" g) y                       "The setup has stopped.")
3 n4 ?" b  F2 ?( Q6 u) @    stop) U$ y4 l5 y* Z8 E/ ?7 b: P6 q/ X) L- P
  ]
3 b! {; s8 ^( E; d% W1 J4 I3 N; c* ~! H& \8 U1 h& P' n
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
. u- M' X8 v6 j7 \, H/ Q$ w1 s  crt num-cars# F7 W$ r  P: L6 \' a
  [
( O: z! ~/ v& C2 K5 w5 X  C    setup-cars
1 o  K2 \  {0 T+ ^7 Q2 E8 @3 v    set-car-color
! Q7 k6 ?& B. _! p; R, V  _- \0 ]+ |6 B    record-data
5 v+ D% X& ~5 V2 R3 \  ]7 _/ x; R7 e) r6 |  ~, C; K" n
6 {# Z& n6 l7 c- N) d# v
  ;; give the turtles an initial speed
$ y. n8 @8 l. I  ask turtles [ set-car-speed ]4 T2 t0 j" I- t. ~8 n. ?5 m+ U, g
$ j/ U6 f1 d& o) C+ t% P: ^% r, s" e0 T9 d
  reset-ticks
/ \7 V( k& B5 wend* W( a3 N. O+ X0 ?% L, Z, c
  D! Q2 a0 p9 L, P0 L1 K& d
;; Initialize the global variables to appropriate values/ _8 _. G1 `, Q% Z  G' t5 _
to setup-globals
9 j1 W# v+ ~- f2 H9 G* J0 ^. N  set current-light nobody ;; just for now, since there are no lights yet
2 q! r7 d. t& e6 b- Z  set phase 0
- @4 X0 Y+ M: T% ^) U( O. @+ [  set num-cars-stopped 0* q5 e: |/ i, x+ ]
  set grid-x-inc world-width / grid-size-x
# ]/ v% F  I9 y; e2 A+ z9 Y; M  set grid-y-inc world-height / grid-size-y5 n5 S, ]* }& L! ?4 w+ a0 q6 ]

& r$ r% K& E& [3 U( q9 C  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary! n: T0 o) \2 D) }. R
  set acceleration 0.099( m5 O% z* o6 D" n/ J  r; r
end
# z* Q) n6 b1 V7 }. e& h/ N! p+ G$ T5 |$ ]5 Y' h2 o
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
  U( F; v$ C' U) L" ?# B$ T# K;; and initialize the traffic lights to one setting
# ~$ n. c4 f3 {# o- C4 Uto setup-patches
4 A' J/ d- L7 V2 ?  ;; initialize the patch-owned variables and color the patches to a base-color
8 e1 Y9 \1 F2 ]8 L  ask patches! x. x8 r# N3 P4 \" }5 _% K  n. p
  [% A' f" {# i: P6 F" j6 [
    set intersection? false
+ ?( c3 r0 f) o, y4 x    set auto? false3 E! [+ a  h3 P% @3 E$ I' y
    set green-light-up? true4 l+ W( ]- h  y  m3 b: m
    set my-row -19 i4 J1 x0 N, y" w( o: |
    set my-column -10 M) _, m9 u; c
    set my-phase -1
& Y$ c9 E* p5 H4 p: z3 W- m    set pcolor brown + 3
8 Y+ g4 V* ~3 d" x2 \2 s/ H: |/ Q  ]. K! o, E" e& k3 W0 W

" [5 o! s: ~5 ?3 m0 i3 _  ;; initialize the global variables that hold patch agentsets2 o8 S0 ~( S  `! E. H6 r
  set roads patches with
0 I- l+ a# ^- T3 K  t% m; D! v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( y3 j+ T! m2 [: @5 H    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" V3 n! [& F  a6 `% F  set intersections roads with
& a. A* c. ]; e9 h# B+ Z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
( A, b# Y9 }- w% N* `1 u    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% N4 Q8 v- P7 L- B
2 \7 ], g5 U% w; y4 L! u  E. D; t
  ask roads [ set pcolor white ]" z4 {5 z9 g; Q, R; w" m7 h; I
    setup-intersections( k& m9 g% P+ O# I* p
end* ]1 m8 O  U( k* H1 d' i6 r- r8 }
其中定义道路的句子,如下所示,是什么意思啊?" N5 X& y/ Y& Y2 W0 G
set roads patches with
) C; o8 m& N8 p; W7 s1 a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' U3 s, t+ b+ y( z- a
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* Z. k# g5 J2 O2 A
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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