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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。
) v" T. ?9 }. Nnetlogo自带的social science--traffic grid这一例子当中,3 x1 S' D" _$ x8 U! m% ^
globals4 ^6 q- I7 d: W( B
[, z- H' v/ B$ |
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
- l- I/ O' h9 \: l* y3 K2 J  grid-y-inc               ;; the amount of patches in between two roads in the y direction) G6 H" S% _$ K# E
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
: J, S3 h4 b1 w. f                           ;; it is to accelerate or decelerate
2 m  d+ w6 [) ^6 Y$ a2 \& i  phase                    ;; keeps track of the phase
% X* ^) |& p9 f) \) M  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
. f1 a! d: E- }* K. `7 t  current-light            ;; the currently selected light
8 F2 R6 j/ O2 a. x* a( S9 D7 E8 K$ r
  ;; patch agentsets
9 _4 \) O, G3 I( b& ^9 B, K; ^* P  intersections ;; agentset containing the patches that are intersections3 a+ C+ c/ [- B% X* s$ \& A
  roads         ;; agentset containing the patches that are roads* q4 {* S7 O6 ^( ?6 O! _" h
]
: Z: O6 K' B" i$ t! p# c
. |$ Q; h* `$ D; M" F, \1 K/ lturtles-own
- f; M0 J( {5 I: _) s[( N, }( m! W1 p( ]% p+ s
  speed     ;; the speed of the turtle+ l! `% j! a- m  ~" G
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right2 l1 U9 X, p7 _: V) l# c( }
  wait-time ;; the amount of time since the last time a turtle has moved
& p9 |! O. r5 B9 t1 ]" T]/ k7 d. B$ P# k0 R" }' E8 S

8 D' p% @# f, D7 s- k' u  jpatches-own( u' M3 t+ U( d$ E7 p0 c/ r
[
7 @  j% _6 Z2 B8 P. ]  intersection?   ;; true if the patch is at the intersection of two roads
" c. L4 A2 g. X, w4 K1 u& O5 x  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
4 l9 ]+ t% l/ M+ y) C6 f- W6 R                  ;; false for a non-intersection patches.2 p# ^3 S* q+ Q
  my-row          ;; the row of the intersection counting from the upper left corner of the1 s( C5 ]7 N  Y. _
                  ;; world.  -1 for non-intersection patches./ ^  p* p" A& P# H5 G
  my-column       ;; the column of the intersection counting from the upper left corner of the
9 |: Z( p8 O, K7 H1 N5 f                  ;; world.  -1 for non-intersection patches.
! y7 r! a# ~2 ]# q* B, W  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
7 i0 \3 O' a  y  auto?           ;; whether or not this intersection will switch automatically.
* {) M9 R% j$ H: z" |8 A4 l                  ;; false for non-intersection patches.& C# \9 M5 B* A2 l4 ?3 H( d7 k/ k0 x
]9 }* P9 W" F0 i( ^8 l* L
# A0 @/ }3 |: ]7 x5 p6 i
! h' g$ T$ z) f) Z7 |
;;;;;;;;;;;;;;;;;;;;;;
6 a8 z$ k5 m& p5 p0 y;; Setup Procedures ;;
! q2 G! z* C: A0 W. H8 ~6 B;;;;;;;;;;;;;;;;;;;;;;
0 N, f' C2 {2 G) M
2 U3 E0 _! j" A7 k;; Initialize the display by giving the global and patch variables initial values.
8 q* w+ l0 }+ s, T2 d) R;; Create num-cars of turtles if there are enough road patches for one turtle to! ]! ?6 U$ }/ E* t: ?" I1 ]& Z
;; be created per road patch. Set up the plots.% b. Y. p2 T7 ^
to setup
- p4 G' x6 _+ E  ca! A5 a6 _% ^2 I+ p8 \5 I
  setup-globals) u4 K' ]) L6 e+ A" z/ L

2 {" n" Y) j5 Y: R- Z7 t  ;; First we ask the patches to draw themselves and set up a few variables# K5 c+ w9 o7 i
  setup-patches
& A/ o5 {, n3 V' d7 e- ?$ G  make-current one-of intersections
1 Z, g1 k9 h$ j0 h# n: \  label-current
4 ?! v& Y8 `8 [+ O  L4 v5 g7 m- S% i- F$ G( ?  k
  set-default-shape turtles "car"2 b  V$ l- I; S$ T
0 d2 F, ^$ Q3 Y/ j' L% ?
  if (num-cars > count roads)
  r5 D9 C2 `: F- p) h  [, U5 ]6 `/ h1 v+ J, q& p
    user-message (word "There are too many cars for the amount of "( p8 d3 _4 S; y& R. k5 [/ ^
                       "road.  Either increase the amount of roads "
) p, g. o8 X0 L7 A( a' U7 ?                       "by increasing the GRID-SIZE-X or "3 ~  s- P# r5 R, o5 U: q
                       "GRID-SIZE-Y sliders, or decrease the "
; b. c6 O% G) g% p- c8 n                       "number of cars by lowering the NUMBER slider.\n"
- o& Q) O$ l- Y( x: t9 Y                       "The setup has stopped.")
( s; X! R; F: C4 p. S0 Q1 `    stop
5 Q4 u8 G" m- Z2 |6 J: Q  ]+ ]/ I$ U9 U/ U, F
* ^1 @# i3 s* a: g4 R3 ]
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
. }# O1 w7 c! Y! S0 N  crt num-cars' t. e3 n+ V+ h0 X
  [9 e+ g! E2 h9 `1 E4 W
    setup-cars) n4 R2 `) m. b6 \
    set-car-color$ i8 ?3 Y1 n9 s: T) |# ~
    record-data' u( c( a3 Q$ N# O$ X+ @
  ]
5 F7 a8 u6 B  u+ T" j8 s  d% j
6 R$ J/ w5 J* c4 P  y  ;; give the turtles an initial speed
* \& t; E8 M& Y. W. |  ask turtles [ set-car-speed ]( W# e- c) Q  e6 [% K' ?- x) ~

: k  G2 ~: k2 B* a* a% O  reset-ticks
  O, t: \. j% K% ]0 }3 L( n. Zend
2 ~% @. {3 ]: V8 F' d; [+ V/ ?$ z2 w8 u
0 M5 h+ ?. z3 @0 }. d;; Initialize the global variables to appropriate values
  y: M3 |7 u: Z1 d& j  p' Vto setup-globals) P1 P9 R# f5 Q, _, c- R2 \
  set current-light nobody ;; just for now, since there are no lights yet( f" K" Z$ W! ]7 ^( n  G" I
  set phase 06 ?3 A" C$ M; m- v6 t- O' Q
  set num-cars-stopped 05 Z: h0 c  }9 E3 H+ x
  set grid-x-inc world-width / grid-size-x% O7 T  o+ V1 H# }
  set grid-y-inc world-height / grid-size-y4 C2 S7 n  I; N1 I8 ^% y
) c1 d5 c, [% P3 l% v( v
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary) J& n' N- ]' g
  set acceleration 0.099
. ~$ Q$ \; s2 v/ dend6 @3 u1 N4 l7 ~. v6 G

* |) `3 T& l2 j: b/ y/ `;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
% ^: h$ |, `( G% e* ?;; and initialize the traffic lights to one setting* s  w; ?1 ^7 ~+ m
to setup-patches6 s7 j3 Y5 z" m) h7 v0 K  T
  ;; initialize the patch-owned variables and color the patches to a base-color
3 w0 m4 i8 O7 ]8 t+ n  ask patches4 \$ [' u0 T, }. g% W
  [! D) H# P- {0 T8 \; w
    set intersection? false2 _. L$ T  T: W* y. |8 n
    set auto? false
# s! g% d+ g9 X' n) q# C* w    set green-light-up? true
1 V: c! r3 `' h    set my-row -1% w4 ~- U/ I% \+ o# O0 H
    set my-column -1- J- B, V1 Z% h
    set my-phase -1
3 `: c) D* z8 W    set pcolor brown + 3
1 P1 _( y, V/ a. C+ {  ]
5 {8 n- w. o# E5 }
3 R3 @/ ?' R8 N$ z1 d9 A: \  ;; initialize the global variables that hold patch agentsets
& A6 U( j' X0 f" I2 ~  set roads patches with
+ ~3 y/ ~% ?+ r4 k3 J. K- [. h    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 F: c2 i6 [6 ], F  p    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. [! a, U4 |' P8 j% O
  set intersections roads with
! |4 `% Q6 u: k5 l' h2 X    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and+ C) E1 m& Z# v# u7 E+ z8 a) k
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 x# l+ q& f. j
- d; P4 o: w8 Y  ask roads [ set pcolor white ]
) A1 I( R- _# z* N7 ?# Q* A9 y    setup-intersections4 b; A4 x5 \' q+ Y
end/ O# z7 a) w. g* A& e) L! E8 B
其中定义道路的句子,如下所示,是什么意思啊?
0 `9 \1 Q0 E$ ?" g6 m5 W set roads patches with) I$ _" g- m' v. T$ z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* T; K! ^0 X- e+ S3 H+ J- U
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( w4 V1 q: a& x: n5 Z! c# j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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