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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。
+ A- V# z0 A- Z+ |( A) Ynetlogo自带的social science--traffic grid这一例子当中,
7 c1 U2 ~- Z$ b3 U# W0 Pglobals  ]$ }* c2 f; `1 L
[5 b! A/ U* O  v* i; Y. |3 Y9 b
  grid-x-inc               ;; the amount of patches in between two roads in the x direction, M& c) z# q. Q' k0 o
  grid-y-inc               ;; the amount of patches in between two roads in the y direction, ]4 h1 h7 G% S6 [5 m3 W- Z
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 P+ H" V/ X  S  f+ v) Z* A
                           ;; it is to accelerate or decelerate) g& M: @! y& N& Z, W, a/ N5 i
  phase                    ;; keeps track of the phase
# V9 `1 w* _' A) {( z* ?  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure' N' {7 N' n  X
  current-light            ;; the currently selected light, D" j/ |. x/ [9 W8 n. E" \
9 r4 d0 m9 ~5 `2 {# o7 W# B
  ;; patch agentsets; H# }! E8 f9 P- O4 v9 X
  intersections ;; agentset containing the patches that are intersections  I- Y3 P' n, x" R- L
  roads         ;; agentset containing the patches that are roads
! b- r8 a$ S/ M6 x' u6 Q: |' x; []
/ H& d; d" w) L
" E6 A6 j! ]" k: Pturtles-own
! O& I6 B/ j: j7 |( y2 T( q[& N" y  n# Y$ o5 ~( ]  ]( D
  speed     ;; the speed of the turtle6 i/ s- K0 t; Y  Y- }3 e6 V: i% P
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
0 V' t+ ?8 J$ |; q5 ^8 x  wait-time ;; the amount of time since the last time a turtle has moved
7 N9 G: g6 S- \+ M5 z]. s7 m6 ]6 I8 K9 T+ L1 V
# J9 t2 V/ N7 t( o4 J
patches-own  p2 P% j% }' W1 v* l" X
[
7 c$ K1 n4 L% l, t8 y# I  intersection?   ;; true if the patch is at the intersection of two roads! U- Y8 P  j  o# i: ^
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
: ]1 s+ K% }, g                  ;; false for a non-intersection patches.
- R1 A  v3 F$ U' v8 Z  z7 w  my-row          ;; the row of the intersection counting from the upper left corner of the% D1 P( k' _4 ~) S
                  ;; world.  -1 for non-intersection patches.0 \" l9 n% V( w+ Z
  my-column       ;; the column of the intersection counting from the upper left corner of the
6 W1 t+ g5 p* R0 f2 W, \                  ;; world.  -1 for non-intersection patches.- l) Z8 n! Z: ]' X* ^( O7 c" k
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.: ?, _4 J) L2 W% k
  auto?           ;; whether or not this intersection will switch automatically.
4 z8 o* m6 J4 ]; H1 }$ Q                  ;; false for non-intersection patches.
. i( ^  f4 G# \! o+ Z: J" u: ~8 F( Y]
! X1 [3 [0 o. C: l( V2 F0 B7 I( {; Q

! ]" O# r+ g) j! B;;;;;;;;;;;;;;;;;;;;;;0 l: F' k7 T* q6 c1 r  {% `
;; Setup Procedures ;;
5 @6 |7 h' A1 k2 g: C;;;;;;;;;;;;;;;;;;;;;;! c, t" }" Y* j$ \" v) @

7 v$ U- ~2 A6 V4 d;; Initialize the display by giving the global and patch variables initial values.
' w; |1 y- |% W3 r, ~" P! R;; Create num-cars of turtles if there are enough road patches for one turtle to# O3 x5 E9 u0 f% y9 R) |! {
;; be created per road patch. Set up the plots.5 c) a# p" H6 m8 l
to setup
7 w' J, N$ N" N8 }  ca
6 t( l# b  V% ^! K  setup-globals
# L  C; m2 X+ |6 i$ P: s- e- ^' j+ i4 [. ^# {; Q
  ;; First we ask the patches to draw themselves and set up a few variables
. u2 r% T7 w; w& @1 X1 S  setup-patches: P# E. B: u, H1 S. ]
  make-current one-of intersections! x- e2 e- Z5 y' d6 o
  label-current
' l% l; z) h- B- d4 p
. s; x9 u" R( v8 O  set-default-shape turtles "car"
6 v/ v& _8 P" u  z
3 Y3 D, U. r0 H4 [. P  x& n+ ~  if (num-cars > count roads)
# g4 l9 H/ T7 ~8 b; c& ?" a: z3 o  [
7 c# L# P' J1 B* K6 ]/ e3 O    user-message (word "There are too many cars for the amount of "
( T! D/ {' H- E  v% t0 B                       "road.  Either increase the amount of roads ". k2 G3 r0 Y, ]6 e0 z3 @! \
                       "by increasing the GRID-SIZE-X or ") G& x8 \2 t9 P
                       "GRID-SIZE-Y sliders, or decrease the ") i7 P' Z: O& p4 \% Q( ^  l( k6 h
                       "number of cars by lowering the NUMBER slider.\n"
$ m9 H4 {$ P$ s6 Q; R                       "The setup has stopped.")
1 U3 T3 N5 X& f5 Z    stop' Q4 E) z( U8 U! D2 x" J# U6 b; r8 |
  ]
4 l& T/ c- J6 z3 T
) h) i( c4 e# Y& A- A1 T$ ?  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
2 c8 c4 u/ r+ r8 b6 d7 R% r  crt num-cars5 q( l  _# E. M8 `1 x( K4 ^* U
  [
- ]" I. c) t3 y' o7 ]    setup-cars
* r2 I8 \7 S  g0 z8 F    set-car-color# X/ f9 w2 a! j! f& G
    record-data4 m7 E7 y& N' J2 c9 K0 O7 }1 Q
  ]9 B& t, L3 \7 i: N. W3 R
. D2 z/ W9 K9 c+ ~# |' r' X
  ;; give the turtles an initial speed
& U; e* L/ `* t; p  ask turtles [ set-car-speed ]6 g$ n8 m# b; C+ l
& m0 g- H* c# P
  reset-ticks" f1 O! @5 F3 V/ n/ ]7 w' S* ?7 ?
end4 _8 d; m" C6 ~5 x. [2 F

% h& O, C6 @! a$ H;; Initialize the global variables to appropriate values) `: U; I7 x+ F0 ^; F  d/ M! h
to setup-globals8 g$ x, ^2 i. V$ t# d9 g% n
  set current-light nobody ;; just for now, since there are no lights yet
- P# x7 q; S4 [! S  @  set phase 0
7 Z4 q" [' e, j  a4 x. {  k/ J  set num-cars-stopped 0' O6 a1 n" S& R8 \& K$ m
  set grid-x-inc world-width / grid-size-x
, T1 p& B7 v9 Q! T! i  set grid-y-inc world-height / grid-size-y2 P% A+ T* P# J/ Q

" _+ Q7 D) F) v- I1 K6 O  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
$ X+ U( {2 p9 f, ?' s$ t  set acceleration 0.099
" O; Y: c1 e/ V/ Bend
0 @# n' ?+ L. ~, }0 |% f
+ Z) h. ~/ B6 N4 y  k% A;; Make the patches have appropriate colors, set up the roads and intersections agentsets,4 X' Z5 P/ {% l' f1 K4 _
;; and initialize the traffic lights to one setting: w1 k# _6 F# I. U) @: Z" b* L6 T( E
to setup-patches8 ^) y7 Y4 m/ N, f9 r
  ;; initialize the patch-owned variables and color the patches to a base-color
' l4 B3 o, C3 b8 {! B  ask patches
4 \; G6 j1 Y5 b% m$ r+ F  [8 v' V+ T7 L1 o8 \: `$ ]1 T
    set intersection? false1 [( @) m$ N3 p9 y: n
    set auto? false' r: j% r. m8 P5 Q, x2 A6 i
    set green-light-up? true
1 G% d" n9 x' r: i    set my-row -1: ?1 y' L  J7 ]" G/ a
    set my-column -1
) t# U6 A4 D3 z5 h; R    set my-phase -1
; x9 u9 {2 d& k    set pcolor brown + 3$ [" \* q. ~) ?% S3 ]
  ]" [) y$ K5 Q0 m, y, [7 ]& x
0 k* @( B5 a: Y4 u7 m
  ;; initialize the global variables that hold patch agentsets
" g! e3 @% B5 |/ k& a, O  set roads patches with
( I) o6 h7 z9 n& g0 M    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- X0 Y! p5 B3 U+ g* \3 G+ d, k4 @
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) s; X7 F* p+ {6 V& D) K  set intersections roads with
. I1 J% M6 }$ Q7 C    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
3 g1 ^- i" z1 X' g# e    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' X" N  T4 [: I  D5 \1 |5 Y0 F6 A6 |0 K$ l% g8 W4 ~5 o9 @! h7 _  ^  A
  ask roads [ set pcolor white ]
$ K* X; o% a1 }# _; a    setup-intersections
$ D3 p) J3 K8 D# C2 Uend  j" \+ c* i: w9 m
其中定义道路的句子,如下所示,是什么意思啊?) V  D. n+ ?' b
set roads patches with
; C, m  d$ A1 q; V    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! j* D, ^3 S1 x0 `$ G: q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; x7 A6 ?$ P3 b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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