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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。9 c% w$ b: K$ F( r% M% Y. ]
netlogo自带的social science--traffic grid这一例子当中,. V% A# z5 T7 x0 k9 @- X
globals1 j' p+ }) @! E- F! t/ Z1 p' A  T/ V
[
* Z) Q4 |9 O5 q9 q& @; H1 D! h8 E  grid-x-inc               ;; the amount of patches in between two roads in the x direction
8 f! D6 x1 u% M& \  grid-y-inc               ;; the amount of patches in between two roads in the y direction
/ W5 D7 n1 L: f* a  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
, f& ^2 e7 g3 Q, p* G; q0 U8 |                           ;; it is to accelerate or decelerate
! ?; X9 g" Z& g; o- @& \- U$ f! Q, X  phase                    ;; keeps track of the phase8 b$ e( M0 K* f% G8 l+ _
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
1 P" V- @* M3 C  current-light            ;; the currently selected light: g2 ~: A( f6 s

: P- \" G6 D/ H( j' r8 W! N  ;; patch agentsets
: z! H* Z5 X( l7 ]8 p  intersections ;; agentset containing the patches that are intersections
  t5 H. p) t1 X+ O* t# q4 r  roads         ;; agentset containing the patches that are roads/ l% r9 |$ p& U  L: U; @
]
% @7 U- V' b  I0 R) F3 N9 c1 M/ P* I# u9 O: T- F8 v
turtles-own" L% U  \3 M* u
[; h) K! U, ?  [. i; U
  speed     ;; the speed of the turtle6 Y9 Y) s8 q. @, J7 x# o* e' ~0 K+ V2 s3 A
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right2 m5 [. F3 T# `  P8 s! A- m
  wait-time ;; the amount of time since the last time a turtle has moved
7 y8 l& R( Y+ E' M( X2 H]
; |9 ?  j/ j& O! {% f! G
7 I# Z  y( W2 S# L8 K2 K& p9 d, o' Spatches-own7 z! ^- i/ G' A9 \2 i
[
3 a7 v" g4 C- L9 {! ]7 z  intersection?   ;; true if the patch is at the intersection of two roads' q9 ]& G+ P8 r( D/ T; ~1 d( j0 A
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.; I" j6 C0 {; M5 ]
                  ;; false for a non-intersection patches.7 s9 ~. f8 Z% I( K* h" o
  my-row          ;; the row of the intersection counting from the upper left corner of the
$ E: \  `4 j* \+ h9 {4 {/ B                  ;; world.  -1 for non-intersection patches.
4 {* w0 D3 h+ t8 t# n% C  my-column       ;; the column of the intersection counting from the upper left corner of the# ^2 \/ x& }4 \0 ~5 a. c
                  ;; world.  -1 for non-intersection patches.
1 Y' K, `& P& y" t  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches." o% l1 [1 E* K9 Z$ [/ N
  auto?           ;; whether or not this intersection will switch automatically.- N/ g4 ^3 ]4 ~3 I
                  ;; false for non-intersection patches.
2 ^2 ~0 c1 |' o* t& V]# F5 k8 [  P# d4 y2 s$ I# a8 a! Q7 j

9 P% m  k1 P- }; z. u4 _$ {5 B$ ^: p6 l" o. F' i" R2 @
;;;;;;;;;;;;;;;;;;;;;;
, e  T( q3 j$ ?;; Setup Procedures ;;
, e7 ]: |. M, N5 N" \( r;;;;;;;;;;;;;;;;;;;;;;
+ g/ k( a" D- Y9 W
! @* _3 F' m5 E5 E8 D;; Initialize the display by giving the global and patch variables initial values.4 Y3 j1 E( Q$ h$ Y
;; Create num-cars of turtles if there are enough road patches for one turtle to
# e4 ~: u9 j7 A9 [1 H;; be created per road patch. Set up the plots.& B: I+ r  Z! t) p
to setup! L9 \  H* r3 A8 c
  ca; h& P3 S* B+ J! C
  setup-globals, K5 H# r; \" v+ }! y- O9 @* X! e

' B8 k: n, ~  y1 L7 k  ;; First we ask the patches to draw themselves and set up a few variables
0 n0 m  R$ l7 _1 _. j5 z  setup-patches
( i# j. n0 B) ?6 I' U) G0 t  make-current one-of intersections* J- v8 B8 i$ ?
  label-current
5 V! x  }) s5 d/ V
; u9 Z9 }% A2 N3 e  set-default-shape turtles "car"
# j9 l% S: Q( k
+ x7 M% h% E9 {! v4 v( R  if (num-cars > count roads)
- [2 n9 N# B1 S# T9 A  [/ h1 O% E7 j" Z
    user-message (word "There are too many cars for the amount of "" Y5 T* x' m' r, B0 R, k. P9 E3 R
                       "road.  Either increase the amount of roads "
9 _' e  [, r$ t+ ^                       "by increasing the GRID-SIZE-X or "% w, w6 ~- S% I; ^2 o5 e
                       "GRID-SIZE-Y sliders, or decrease the "
. r' c1 b  H& b- U  M/ e% z                       "number of cars by lowering the NUMBER slider.\n"5 M2 a; e6 w3 ~
                       "The setup has stopped."): _" b9 V* M! O! C
    stop6 a: P( _) V$ Z8 n; N) p
  ]9 Z8 E  ]4 A, V* j
6 L1 S% o" P3 ^' P+ \! O# Z( X# K
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
" n9 a$ E+ Z; V% M8 \) {0 G) O+ h  crt num-cars! n9 R/ T5 ^4 T' l3 a
  [! c% {" o: u# u8 j0 K: u# [
    setup-cars
. h6 W+ ]$ }9 F    set-car-color
% n' c* K+ Y- l' \0 q; @# \    record-data
! ?0 D; Q1 e! ~6 B+ J% j1 D8 n4 T" c  ]# }5 U% G0 g. f0 S4 m) y* G& L
8 ^( W& z$ Q3 q5 ?
  ;; give the turtles an initial speed
0 c0 V0 ?2 k; q  ask turtles [ set-car-speed ]
/ r+ O# u7 \! _- m/ Y: F! g
: F  q1 Q( R/ G  reset-ticks" X( t+ r$ _1 ]
end
* t5 x' m! C) {  A- u- y+ p" p& L' {% n) e( J3 x, g
;; Initialize the global variables to appropriate values& I9 V0 g0 ]' t
to setup-globals5 }; o( c3 l1 j
  set current-light nobody ;; just for now, since there are no lights yet
* b( U+ l8 m) G: M2 A9 I7 g  set phase 0' Y6 U$ u- x0 a. L+ ]% l
  set num-cars-stopped 0
" x  }& L3 |6 j6 J3 t4 K  set grid-x-inc world-width / grid-size-x8 @- N9 n# {- r0 [! y
  set grid-y-inc world-height / grid-size-y
8 R) _5 e' r6 C/ V& W
2 c$ J. X3 @- [5 v$ y1 H, q  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
$ x$ U7 _( e. c& g  set acceleration 0.099# d' m7 _/ O. |; h/ j( }% @+ t' E; c: C
end
8 m* q5 {- |) w; ?2 r* C4 R1 C& {4 Q$ v) j7 [
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
6 }1 ^9 }6 z* ~5 f+ m: i6 m;; and initialize the traffic lights to one setting6 g& @( q- a& T
to setup-patches
& }+ e6 Y- |) v  `3 A  B  ;; initialize the patch-owned variables and color the patches to a base-color
2 |* ?/ t! E/ {% ^/ \  ask patches* G& U% e! T' K. K- }* `
  [' l% ?" G& Y' t+ k5 W+ P
    set intersection? false5 k6 i+ c8 W1 N' R6 W, K
    set auto? false
) Z$ M; W6 S0 z4 C# W2 g+ B    set green-light-up? true
9 c6 N& e2 V1 l* j* f& x    set my-row -1
$ v- {4 w, f' E/ I4 ^( J0 Q/ J( C    set my-column -1/ w8 ?/ v4 y: n$ @7 s; m- ~
    set my-phase -16 Z5 f" |1 n2 }& O
    set pcolor brown + 3
; r! O6 V+ s2 R! ~  ]" k0 i' A+ U* N  a2 R
# P8 U8 Z- ^5 W) |
  ;; initialize the global variables that hold patch agentsets
% h& ]# D  G) i+ o/ `  set roads patches with: s# U: I9 v+ Q  M4 c) `( Z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  m9 V; z# ?# L( U    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- C# f) E# O, H4 l' B4 i- t$ V
  set intersections roads with9 f' i% H$ n5 L) p% h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
( P0 W9 a0 \8 {2 T3 M6 Z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; K, L5 ]; M9 A5 m# M& c
+ J5 ^5 N' \: n4 N. E
  ask roads [ set pcolor white ]
/ H* v4 z  m: x( W. _* s9 R5 O" D! [& B: P    setup-intersections
& [. r3 u# P7 G6 U8 Bend/ J9 G1 M7 F7 p. N, ?/ c! O' ^  l# c
其中定义道路的句子,如下所示,是什么意思啊?
# ?: k1 H5 i  N) y- B+ ~7 W6 e: X+ z set roads patches with( l) A% J/ [" _% n1 p6 W6 e
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 w2 N1 [# K, I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% n$ l0 c. }. U
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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