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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。
$ }# N1 T3 P( h  j, c" j6 u, {netlogo自带的social science--traffic grid这一例子当中,# n$ |1 y% P! I# Q' d- F/ ]
globals4 v8 x6 c1 t" V7 e2 I, e
[
: y# x( g+ L3 l  grid-x-inc               ;; the amount of patches in between two roads in the x direction- t, x( D# W! t9 s( J% ^
  grid-y-inc               ;; the amount of patches in between two roads in the y direction6 c- @( s3 j/ d# s' A
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
: `# e: m: b" }2 }: Y' J                           ;; it is to accelerate or decelerate  d% \' Y* h) X. [, P& a& h
  phase                    ;; keeps track of the phase
) y7 [: E! _1 L/ F  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure5 u/ }0 `. x' q# k, d2 c0 u' T
  current-light            ;; the currently selected light# V& N" [  y. j0 h
% \, Z7 x/ _4 e5 t
  ;; patch agentsets; @, R( d6 R) t5 R: ~/ V2 R
  intersections ;; agentset containing the patches that are intersections
5 d" O" f. o6 ?1 _8 h- k; B- @  C  roads         ;; agentset containing the patches that are roads: W7 j0 i( D1 h" ?6 p' d1 {/ h
]- `+ Y3 T$ F. [/ u) ^1 i* t8 [% b0 u
+ N+ m& R: J4 V- d4 q8 T$ q6 S
turtles-own# m: z. h3 \; F  u! Q9 j; b
[. y  ]9 K! j5 W% g
  speed     ;; the speed of the turtle
4 o# d+ @; M% n6 N2 D  G1 t2 f0 y9 l  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
! v' X  D- e: q& R+ g  wait-time ;; the amount of time since the last time a turtle has moved
6 D; a- L' }9 P% D% O9 s]
5 K6 M( w' A# y* Q8 M
$ W% d% H1 p4 S3 S- }0 l  ppatches-own3 o5 N- o: k. i: X
[
9 t5 Q! E* f+ S/ o' `$ |# b  intersection?   ;; true if the patch is at the intersection of two roads9 M: M; `* h; j$ M* S2 c1 g2 f
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
  q- N. X2 u; h3 c# l# Q. y  b4 B                  ;; false for a non-intersection patches.$ O7 F" y; H2 a$ P2 b, f: C3 z
  my-row          ;; the row of the intersection counting from the upper left corner of the9 u2 I7 d1 ^& O& K3 v
                  ;; world.  -1 for non-intersection patches.5 W0 n: [% `* s
  my-column       ;; the column of the intersection counting from the upper left corner of the2 W: s( Y) Y# X& G$ c7 ?
                  ;; world.  -1 for non-intersection patches.6 J3 Q% d3 s- h
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.$ s4 X7 M2 Y, Y$ J
  auto?           ;; whether or not this intersection will switch automatically.+ a' m! E4 ]5 T0 d) n: i
                  ;; false for non-intersection patches.
. o. f% k% X- Q) ~+ N- O]
( S  a& T" z; j5 S1 v2 q+ s' J  r* z" i  P1 L, i

6 B* U3 E& C: Z1 i0 W;;;;;;;;;;;;;;;;;;;;;;
2 ~# F1 Z2 }  d( q2 d2 f;; Setup Procedures ;;2 R+ q0 h; n' {5 Q$ S
;;;;;;;;;;;;;;;;;;;;;;" D1 u& m7 R- V$ O; {. W
6 ^4 u) o# b+ ~( W. \) t1 ]2 W
;; Initialize the display by giving the global and patch variables initial values.$ U7 y9 X0 s0 R) ]
;; Create num-cars of turtles if there are enough road patches for one turtle to
+ U( T/ U, b: \4 P# }8 s;; be created per road patch. Set up the plots.! H3 p. O4 r- J6 r/ I/ Q& O
to setup
  t: F0 i0 H6 K, H4 F  ca
, F  M" ?$ ?  ^8 R1 d  \  setup-globals
2 x) b* t! S% R0 |
/ Z" b* e; v$ c$ ?' P7 n  ;; First we ask the patches to draw themselves and set up a few variables
  S! U; _/ M+ Y  z7 _  setup-patches
* T+ s4 X. L. w% ?9 m  make-current one-of intersections7 k- Y* J( O( ?# Q. N- m5 M
  label-current
( L) ~$ D: ~. ?& v5 C) D( S: v5 d- k" ]
  set-default-shape turtles "car", Q& o, D, l* X$ @
& A$ r) n  B$ X1 i# ?) \' v/ n$ O
  if (num-cars > count roads): f( r# b: Z/ D$ ?& _
  [2 b! H' R) F- j
    user-message (word "There are too many cars for the amount of ", F( L6 i7 N: A9 J4 D
                       "road.  Either increase the amount of roads "
. B# x( ?, m0 v) N                       "by increasing the GRID-SIZE-X or "
& P+ k% K; b: C                       "GRID-SIZE-Y sliders, or decrease the "
7 j5 \4 {' k. n5 o2 n$ g                       "number of cars by lowering the NUMBER slider.\n"2 F+ c* e6 o2 P$ a
                       "The setup has stopped.")
" A, F" d7 h6 j; I' o* j  K1 f    stop
1 @( @5 T3 Y( N6 i6 X  ]: ]* B- v1 ]& O. R* K

7 u; [) d8 A/ n6 C) x- o  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
9 ^7 A2 ^( Y/ d2 x1 f3 F  crt num-cars
/ B% j' \3 `; g# y: G8 {( e  [
) w% Z7 O# e2 t+ @2 X: M: d    setup-cars
% P6 _- H  @& M0 p" c6 O! z* A    set-car-color+ }' f+ C3 a. T3 t" u8 E8 g& p. |
    record-data
  E9 [1 o& a5 _% a# p- b  ]) j) o2 f3 `# M0 U+ ?
) w- m: X( O3 ]: j9 [" W) ~
  ;; give the turtles an initial speed' T) u0 K# ^5 f
  ask turtles [ set-car-speed ]7 n  b& D: a2 u7 Q% V, Z$ ?

( c- p& p% \/ ^" y8 ^  reset-ticks8 R  X6 ]8 ~2 k3 q* o
end* c- C7 O  m8 G% z4 ?  _7 h6 N

! L: D) A4 [! u8 I0 d;; Initialize the global variables to appropriate values& _1 x4 e" _8 `; f" h
to setup-globals
- x$ L. ^, x' {$ O1 Y- z: X  set current-light nobody ;; just for now, since there are no lights yet: E% e- X+ L+ ?+ X( M; U
  set phase 0- l6 V( h" P/ e  b$ Q9 l% v( s4 Q
  set num-cars-stopped 0
3 l' C' Z: Q# D8 n3 j2 u  set grid-x-inc world-width / grid-size-x9 i" ^: Y# t. T
  set grid-y-inc world-height / grid-size-y
0 V, i- E9 _+ [& }1 j
8 d2 |5 W( l8 N8 U) h  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, B& _' ^; C* F! ^' K0 l# d; F
  set acceleration 0.099
. c+ H8 w9 {+ ^+ o# J) {* Tend$ ~+ B: e  P, {/ |( \6 E8 B* Q
, \) O3 h. q. H5 r5 N
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
  b) g* G7 F7 h3 x;; and initialize the traffic lights to one setting' _6 t1 [6 ^# b1 k0 I
to setup-patches
2 D) o; \* y4 s+ H  ;; initialize the patch-owned variables and color the patches to a base-color+ ]  l1 c$ O2 ~( l
  ask patches
  ?# q8 A: H) U. Y$ x  [0 C6 M+ v* h- b6 K4 R4 H  G# B9 M
    set intersection? false6 ?, C% |( `+ r/ B1 E
    set auto? false( k% P- Z: c& g2 M3 g5 H
    set green-light-up? true9 \& ?6 o+ e9 o7 ~2 }, n
    set my-row -1
8 A) W1 b0 [5 k) ?& t    set my-column -14 N! @9 m6 v$ i; a
    set my-phase -1
* v6 ^& X$ I* ~# R; V    set pcolor brown + 3
  J  W/ P; l7 D! u+ W8 ^  ]
0 w8 V4 ~! a: \# q1 c9 ]  g7 o4 s6 c+ V6 b9 F" z: X
  ;; initialize the global variables that hold patch agentsets
' r% h/ |1 s7 {1 D& G  set roads patches with9 g( G7 R2 t9 Y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' ]3 y9 {! n2 n6 j2 R' t
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. }0 M% U9 `& M$ V5 R
  set intersections roads with/ E9 y6 z& o& g: U. s
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ F2 F- }' ?! k* M; Y6 B# w6 N
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; @9 Q$ O9 v+ w: f
2 }! {; J& y, a, F, p  ask roads [ set pcolor white ]
5 h3 _3 g6 b5 J5 C$ {    setup-intersections+ U* H0 n, j8 q0 u* s; V7 k. Y+ \: T5 P
end
, T/ ]. v2 `$ Y! D7 j其中定义道路的句子,如下所示,是什么意思啊?
. ^0 t& c( d2 M, Z1 X set roads patches with
" T- `  a) r" p( A    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) i( J& i. r4 _3 o2 Z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], `, W* w9 U6 T! h5 D! Y1 E6 l8 |
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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