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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 k3 @2 U: W- I3 G* Z
netlogo自带的social science--traffic grid这一例子当中,1 F1 F3 y- r% z2 y9 _6 N9 O; K
globals
7 c" l& w: [! `4 ]) |6 b[; @; |1 b  Z3 S0 N" N3 n2 l5 T
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
; _# _& k% o3 {4 x  grid-y-inc               ;; the amount of patches in between two roads in the y direction/ M2 ]- F; t6 P/ b$ m6 V
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
- i' ^% I  o) o/ }                           ;; it is to accelerate or decelerate
6 p- l1 x0 ~/ K  phase                    ;; keeps track of the phase
0 r, b. U6 O$ p9 K+ o2 C  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure/ f# R  Q8 E3 A/ B* {+ Y. r
  current-light            ;; the currently selected light
! C; r6 B# O* I! Y1 I9 l" h" X$ G
  ;; patch agentsets
+ M7 e; [2 K  D4 r$ b2 ?  @1 W7 r! A  intersections ;; agentset containing the patches that are intersections
* t7 e% F, u2 ]2 B  roads         ;; agentset containing the patches that are roads
# a3 ], y- U5 d; Z, L, L8 c]
& b8 ~% k& L' i3 O
% _) h2 q/ g% _4 Q+ ?6 c4 X# d4 U" Pturtles-own
. L8 [) U/ m5 V' y9 f% Q1 \9 S[8 C0 P2 u$ L( H' r  m* W
  speed     ;; the speed of the turtle5 }9 D% M, e7 _9 w6 U. N3 V
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right- M: S( k9 S, E/ P% W* x- _
  wait-time ;; the amount of time since the last time a turtle has moved( \* Y) s1 g* ]  L5 V- y5 X# y
]1 k# g8 X" F1 L2 m2 A9 T
8 l5 O1 o" R6 f: H
patches-own; ?; U- M) C' ^1 v/ a2 o. P+ I) ]( S
[) U/ Z- _5 z! t2 F' U: M( J) N
  intersection?   ;; true if the patch is at the intersection of two roads
7 H7 X6 Z' ?; ?/ m. q  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
" u4 v1 b* z% F" f' S                  ;; false for a non-intersection patches.; o2 d0 q0 F( H0 ?! L% N! h/ m
  my-row          ;; the row of the intersection counting from the upper left corner of the" g4 {; G$ F2 q% }5 h
                  ;; world.  -1 for non-intersection patches.2 Z  J4 |2 k1 o+ @5 w: s; c: ]
  my-column       ;; the column of the intersection counting from the upper left corner of the
9 H1 Q$ B7 @  X0 y0 I: {                  ;; world.  -1 for non-intersection patches.
0 U) S2 q8 L6 u  Z! W5 B  u! Y& ~  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.) z# L- h- O/ N, F
  auto?           ;; whether or not this intersection will switch automatically.9 q0 `  S0 I9 B0 \- M
                  ;; false for non-intersection patches.- q  N. b2 i8 T" B
]
& f$ r# }0 L. {. V" F/ _* P. @9 ~2 n6 |
( O/ l; v& k7 a3 o& f# g" A% f, R" I- n: ?' ^3 H
;;;;;;;;;;;;;;;;;;;;;;
) n1 z- u! W: |, V/ K;; Setup Procedures ;;/ d: J% q! J% P: ?" v% V
;;;;;;;;;;;;;;;;;;;;;;
% O2 i& O) {* Q, q9 Q7 N0 L3 d4 r4 e5 |4 h  k% Q7 W! ]+ K, }
;; Initialize the display by giving the global and patch variables initial values.
2 Z! D* k7 q# I/ V;; Create num-cars of turtles if there are enough road patches for one turtle to
4 d  E* @: C3 n+ o" };; be created per road patch. Set up the plots.( c- }. ?  G) _( p
to setup8 P3 z) C5 N4 F0 W# E! \* W
  ca0 e9 |) w1 @# H- n5 V4 ?
  setup-globals1 T4 ]  x! \( b5 }6 {5 K; b
4 s8 I/ V# z4 B
  ;; First we ask the patches to draw themselves and set up a few variables
1 z+ B& X9 d4 E  setup-patches5 a3 L7 A! B& y+ l
  make-current one-of intersections' o: v5 N% m  ?, M
  label-current# e, b  t8 k  U' z' J0 P

: m1 T3 D8 i! `1 v+ j! D7 k  set-default-shape turtles "car"0 H! \9 s  m" a, R9 Q* T# W

3 P6 ?) V5 o2 t8 V% U  if (num-cars > count roads)' ?" s1 M+ }5 y" X) o
  [+ a# p3 X. o0 x! e/ c. J8 u
    user-message (word "There are too many cars for the amount of "
! e6 |) c3 \+ h/ s                       "road.  Either increase the amount of roads "
4 ?; T" u" C1 M: i                       "by increasing the GRID-SIZE-X or "
0 |4 ]7 D' o+ F" _                       "GRID-SIZE-Y sliders, or decrease the "! ~7 N: f! ~; r
                       "number of cars by lowering the NUMBER slider.\n"
7 \' i% _3 O& v# {' q! F                       "The setup has stopped.")# C1 {+ j2 M6 Y, e! u7 W. R
    stop
- M1 I5 s/ k' ]  ]
5 `" v, l/ u9 o; s
$ p/ p3 Q4 C$ w/ e  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color7 N' i6 @6 w" X! Y- m
  crt num-cars" z& b: @. M" t& O, \) J
  [
3 t/ y: t% w' _4 T' L    setup-cars
, a$ \( [  O! M( S    set-car-color
7 v6 h( W& d, C& }! y8 ^    record-data
7 D$ {& q+ r% w4 u8 W. X% O. B) a3 q  ]
; N3 R, b6 }# r& Z( S8 Y, Y! K5 P+ ~* i9 C" h. I. |1 j- Y& ]
  ;; give the turtles an initial speed
$ b4 Q; \0 U" P' a/ d  ask turtles [ set-car-speed ]
) f, U. l0 g+ @- J0 V- @  n% k9 t9 t
  reset-ticks
5 R9 e1 I. L" p$ @% p, r, \end# _  w1 b  G% G' L

; f8 d' [3 x* {;; Initialize the global variables to appropriate values7 ?2 M7 W$ q) ~: S5 d' H
to setup-globals
# L6 [6 L. f$ l; r' M5 r, O  set current-light nobody ;; just for now, since there are no lights yet/ J$ K6 H; q2 R/ F( T; i& \; Z
  set phase 0% d- c' w4 @# c* X. V
  set num-cars-stopped 0
3 c8 Q, S: a* L; v, w  set grid-x-inc world-width / grid-size-x: e" ^. H" H6 N. ]
  set grid-y-inc world-height / grid-size-y
& j2 ]: O3 f$ `/ ]) I# @3 p: |% y
; m( {4 y2 ^3 S  Y/ O  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
* D, C( t' l  H) C* c7 p% j  set acceleration 0.099
+ |% t+ x9 {- r+ B1 d9 }end6 t# J8 |/ S0 C' |" X
6 u- Y% H5 j2 F1 W8 v
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
: s, E# x0 y9 `4 f" N* z2 Q# o+ K;; and initialize the traffic lights to one setting
1 b* L1 F: |+ L7 b/ a/ Vto setup-patches1 ^. q# O0 B7 [2 A2 R
  ;; initialize the patch-owned variables and color the patches to a base-color
3 n/ U  a0 i6 n2 L9 O7 V  ask patches
6 G1 I, L0 y% o; d+ m# x  [
3 y) l7 c6 I5 E. ]    set intersection? false( E5 @) l* G2 M2 q. g
    set auto? false
; q: g: l5 l# G7 \, P6 w    set green-light-up? true7 \# m$ j4 v7 Q; I
    set my-row -1/ F' ~3 K6 ~& W9 k
    set my-column -1+ L8 g( a$ B- G, d8 G1 i2 [* U
    set my-phase -1# t" l1 o$ m6 m
    set pcolor brown + 3; M; S3 `* Y( d
  ]
. V* H" ^4 o$ e) t& `- ]8 y, a8 }4 [# r, n+ Z( K% L
  ;; initialize the global variables that hold patch agentsets& M1 b3 E" |2 a3 U# y
  set roads patches with
0 ?  K+ ~7 d0 {$ P3 G    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* Y! H5 l, l  V* E' o( L! S    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! l. ?. ^% z3 x  O
  set intersections roads with, Y( E2 D6 T, U. o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
- Q9 _/ `) L* n4 i( v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 n. F' j+ Z! m
$ Y! m9 @/ w# s/ q! _. L7 _5 v  ask roads [ set pcolor white ]& V, ~2 X% U" P1 e# m
    setup-intersections$ l( ~) l+ j! }7 J
end
" U9 u' R- ]; f. B其中定义道路的句子,如下所示,是什么意思啊?
& R( Y# L6 E4 ?$ g3 I% W7 v' d set roads patches with
( |+ i7 r; `+ [, v7 d    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 \8 z7 L( l  m; F! N. i, p    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! D/ T5 U! }) G4 ?0 z, i& u2 p
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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