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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。& ?& W) r( z. A" e
netlogo自带的social science--traffic grid这一例子当中,
+ o+ M7 i5 N& [+ X, u6 E- ]3 yglobals8 }$ B3 E2 A1 u
[
2 B! a; O2 W# O  grid-x-inc               ;; the amount of patches in between two roads in the x direction
  V. k5 E$ P2 F: m4 I  grid-y-inc               ;; the amount of patches in between two roads in the y direction
; D$ \/ i9 m7 q  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
4 N% U  [  ?) J8 ?& [, h6 ?& [                           ;; it is to accelerate or decelerate, l  x; I0 U) |+ b) i
  phase                    ;; keeps track of the phase& c; h% h$ e' p7 z* C4 w
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure6 E: Y: p7 y% A
  current-light            ;; the currently selected light- k: I3 x) O; R5 ~$ E' a: W

7 x+ M1 j" c$ U  [( e9 D; j2 J  ;; patch agentsets
% j1 Z, R: `7 ]2 R/ G; j0 u  intersections ;; agentset containing the patches that are intersections+ N7 b2 c3 R& i9 C3 o# b0 n
  roads         ;; agentset containing the patches that are roads
5 e! h$ |; t( U) F$ U, q1 }]
" Y8 t# ]1 Q" {1 q# F- l5 V, }6 @6 i. d$ X; M' a
turtles-own
. W1 i7 B& J+ |. w: h& s# y: R5 E[
; x; `7 j* {/ h  speed     ;; the speed of the turtle
& b( k8 j! N0 J. {% k$ h& j  up-car?   ;; true if the turtle moves downwards and false if it moves to the right0 h: f2 G& s0 Z* H; i
  wait-time ;; the amount of time since the last time a turtle has moved. @9 p* R, F* \6 R
]
; ^4 S9 ~6 d4 |0 C# J* s* k$ O) |1 S6 c( I: j; F
patches-own
0 O! K: Z7 j8 \, K* d* T: q[( a  c. g' w1 `; ^! V" C" ~: {
  intersection?   ;; true if the patch is at the intersection of two roads
4 z( Q% z, D" w3 C/ ^6 ]! y0 f  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.2 N! i. ~& a" e  s
                  ;; false for a non-intersection patches.
& v) U/ n# W4 o1 V. A  my-row          ;; the row of the intersection counting from the upper left corner of the
& }, ^; W8 W( K) K* r, N                  ;; world.  -1 for non-intersection patches.
5 s8 _! H1 @  r' F: T$ L. @  `- ~) C  my-column       ;; the column of the intersection counting from the upper left corner of the
$ J# M2 f) g% k6 b. L: Z                  ;; world.  -1 for non-intersection patches.
* Y$ B+ d7 o# K: j  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.# g' B8 f7 n- h5 W& H
  auto?           ;; whether or not this intersection will switch automatically.' d& h) x/ k& T
                  ;; false for non-intersection patches.0 W6 m7 f& h; X6 o& o) \
]
( f  o' c4 Q( R+ y( t: z
% P3 f  [- V4 i/ O6 s. S: ]+ M3 A$ N% f* A1 S* S2 j( Y
;;;;;;;;;;;;;;;;;;;;;;- n6 r1 R8 A  _7 u7 q
;; Setup Procedures ;;
3 o' `0 e9 j, i) c% N& R% p# g;;;;;;;;;;;;;;;;;;;;;;1 y% d1 P" {% Q6 s4 o8 C

% ?+ A  O  {6 @) d1 A( X;; Initialize the display by giving the global and patch variables initial values.1 ^, H" D/ H1 A/ Q  C
;; Create num-cars of turtles if there are enough road patches for one turtle to* a5 n2 D# t# Q2 _+ f) P. O' C1 n
;; be created per road patch. Set up the plots., W2 w* y, x1 [9 l6 i1 e
to setup/ a& _$ }* y' M5 t
  ca
% l& ^  E( {, o( t# `$ a# h' z  setup-globals
. B4 w2 i; q" j. O
' b5 k$ l! Y# e  s( _( ?  ;; First we ask the patches to draw themselves and set up a few variables+ l  t  R' V3 X! s4 X2 f* ^
  setup-patches- f+ T% T. m6 |1 F2 `& O. ?
  make-current one-of intersections
% \, [2 m8 v; }( V  V1 s  label-current' q6 v/ Q* i. G- C4 v: g3 `

$ Y5 t2 P8 B- i, E3 c7 a& M  set-default-shape turtles "car". M* |: ~; S: G% Q' g

* C2 d8 Z1 p3 e3 f7 _% l1 z5 q3 w5 u( f  if (num-cars > count roads)( J/ d) S# N1 c  J9 d5 `  C
  [/ ^% L8 H1 i8 t3 J9 Y
    user-message (word "There are too many cars for the amount of "
* \3 x' \% f2 c+ U) m% ]3 e                       "road.  Either increase the amount of roads "
  @7 K# ]/ P) a7 D% J6 z+ f                       "by increasing the GRID-SIZE-X or "
4 \  K& w/ d9 E, E                       "GRID-SIZE-Y sliders, or decrease the "
) n/ j+ z/ Y$ t# b; e9 C                       "number of cars by lowering the NUMBER slider.\n"
$ |% d* F& V; j2 p& B: O' j0 M6 T                       "The setup has stopped.")0 ]8 |9 a* w: q- k8 v: K3 Y
    stop# O. ~6 [$ [) {) I/ {7 F6 K+ L
  ]) k6 w2 C* O4 q; _
# O* q. S$ d. L8 A
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
5 B* {# p$ E  [/ Z' L6 V  \$ ~  crt num-cars1 g1 d% @* t0 z$ r2 y7 C0 ~. j
  [0 e* g3 q1 P7 D# W. L7 R
    setup-cars
1 q) P) N9 |' J! q- z4 j1 v3 r    set-car-color
7 p+ h5 ~8 _4 Q. [: f0 ~$ C3 x0 d2 y    record-data
2 m% P6 H( h/ U  t  ]! S0 h; G5 D% \1 y  q( m
3 G4 }. U1 E* j7 h1 Z$ E- P
  ;; give the turtles an initial speed
9 i: J* t! d9 _( ]9 S  U  ask turtles [ set-car-speed ]' ^" \1 n, p9 E3 e; a1 P

, b/ T! _2 D2 y; T  reset-ticks
: e- |; G9 z9 T1 bend
  b& ]7 v, p; c+ G+ u1 ~+ n5 s
7 A9 l4 ]' \; z;; Initialize the global variables to appropriate values
. D# [8 @0 x$ O- V/ i5 H. K) Pto setup-globals
5 x4 t) g2 q3 @% J/ X2 k  set current-light nobody ;; just for now, since there are no lights yet% R, ~/ x% g0 O' p; p
  set phase 0; g4 c! c6 K. Q9 D
  set num-cars-stopped 0
, l: \  ?* F: N! b  I  set grid-x-inc world-width / grid-size-x3 y  Y) @- y6 K
  set grid-y-inc world-height / grid-size-y
7 Y/ O( k* K2 t0 g5 k% J# }& }* l2 I% W7 |; e0 R
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, Y. b# Z) |  i/ F0 \
  set acceleration 0.099
2 u& ^. Y) s0 s* Iend
$ @, w7 z" u# [, O5 L% C6 K) [2 r# E: Y  `2 g
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
* }6 b. D% r4 A4 ~  ]& d9 F. _;; and initialize the traffic lights to one setting# r- e- {0 _& N1 _
to setup-patches6 v0 k: f( R" j$ [; ]+ e/ P" ?
  ;; initialize the patch-owned variables and color the patches to a base-color
$ T4 }; m9 @, C  ask patches" w6 \8 i- M2 V# t# j, ]
  [
% ]) ]# T+ o, v  I2 ?    set intersection? false! I. }. E0 [/ o; [9 \: Y* U
    set auto? false
: w. l, L7 z5 P5 O    set green-light-up? true" S: L: x- j5 y) y
    set my-row -1
. j7 P8 Z. y0 {  W4 a* A3 C    set my-column -1$ {( L, o6 {% b: |/ @* i
    set my-phase -1
1 r! F+ l: [9 Q/ ~/ ?    set pcolor brown + 3% h4 E+ O  h' c' h4 y) J" l
  ]
& M1 v; k/ B/ r4 [- H* A' ^0 t( w3 E% d% W0 p0 G
  ;; initialize the global variables that hold patch agentsets1 V, u* g" @7 H) v3 N# n
  set roads patches with) d- ~6 h0 q1 T! U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. `2 {, F: P5 f1 R% T    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ V3 G1 D  o* ?  set intersections roads with  G/ W9 H2 O* `9 ~8 z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
5 z3 h5 v0 {" b& O) K! m    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' T' N- M% `) L4 T9 k! C3 X; ]0 G
/ `8 o  H  L- A$ t3 ]3 F; S" ~
  ask roads [ set pcolor white ]1 A9 ]3 M6 C; H" M4 e
    setup-intersections% U7 }( x, a/ G6 y. J
end4 T8 u9 ?2 K- e: [" u9 ?- T. ~* u8 s
其中定义道路的句子,如下所示,是什么意思啊?
  Z2 {* W& _/ E0 i! U set roads patches with
# H0 ~" u- @# a# h7 S3 [    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
; Q1 q% B1 ?: Q6 r8 Y3 q) i- S    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ A6 V) D) ~/ ~7 x- f- Q1 n: v1 e; R
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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