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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。
! }% I4 y1 O% J% T6 \netlogo自带的social science--traffic grid这一例子当中,9 s' o& j. o$ l/ s
globals
/ r8 }- y2 C0 V7 p; i' M[1 W- i% R* V. U3 W2 E( o  H2 _. c
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
9 I0 b! v0 g) g) }4 |* V" I# M- a  grid-y-inc               ;; the amount of patches in between two roads in the y direction1 q, \4 p( ~; o# [% D
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if" M  d1 g) S. t% `8 S. c
                           ;; it is to accelerate or decelerate
) r1 p5 O+ n% x4 B  phase                    ;; keeps track of the phase
+ J/ u: N! {9 d' l$ F, K6 C% m  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure6 s! V+ g+ b" G# V3 W% U) t  @
  current-light            ;; the currently selected light6 r) b6 K" ^% `4 M0 z  X4 [. T2 o
3 Q# \( [* \- x; i/ s
  ;; patch agentsets1 V. {) }0 f- Y0 L8 S
  intersections ;; agentset containing the patches that are intersections
, J/ e0 \- U$ q+ T; k& T7 ?4 l* d" S  roads         ;; agentset containing the patches that are roads
2 S$ }& n' x. s]0 K2 ?4 F$ J3 ]

2 Q- g! B* I4 O: v6 Q0 x9 Hturtles-own/ V5 Z: N1 O/ y9 L: ^
[1 b, a% W  {3 ?. o4 y; S
  speed     ;; the speed of the turtle
& C! v- x5 R2 W6 y- A  up-car?   ;; true if the turtle moves downwards and false if it moves to the right% t" v* ?: N+ U. ~3 Y- J: S
  wait-time ;; the amount of time since the last time a turtle has moved' [/ T7 ]( f& ~) h& p
]
1 \5 m* _1 F/ C6 L2 P% c% H
  Q: ]# G; D4 x& }3 t. a8 E; cpatches-own
- v  t0 Z( K! K4 f  o[
5 `7 r% y5 t* q# G$ b: X  intersection?   ;; true if the patch is at the intersection of two roads
. _* U' O# m# C  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.* U# @  P" R9 r& `. Q
                  ;; false for a non-intersection patches.$ I2 l) q0 i9 x
  my-row          ;; the row of the intersection counting from the upper left corner of the" w8 J3 U4 M" ]& ~6 C! c4 j7 L! g
                  ;; world.  -1 for non-intersection patches./ `1 k/ B# I- P# h
  my-column       ;; the column of the intersection counting from the upper left corner of the
  }% f) S1 C8 p% i' U                  ;; world.  -1 for non-intersection patches.
' [7 f% `1 a1 o8 h  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.3 `+ A& E+ m- x8 c4 p& Y
  auto?           ;; whether or not this intersection will switch automatically.
0 Y: A% E9 E/ ^$ g. F                  ;; false for non-intersection patches.
6 I% \2 Q3 v8 [; ?4 ^3 n# W/ m]
; O; @' `# X+ O8 h$ V8 q9 o: T$ `* h+ d, i* Q& R
0 {! H) W/ Q5 s( C6 M
;;;;;;;;;;;;;;;;;;;;;;' e' @' w! f& N$ m- n
;; Setup Procedures ;;* d* p" f; u/ v0 f
;;;;;;;;;;;;;;;;;;;;;;
8 o  k9 b7 ?6 W$ t- n- v* w3 E$ ^$ d. _( J: _  Q3 O4 q) ]1 S
;; Initialize the display by giving the global and patch variables initial values.
  q# \5 c1 @( b  }% Y;; Create num-cars of turtles if there are enough road patches for one turtle to
9 z( W  |- t5 ~4 ^0 [8 m9 y;; be created per road patch. Set up the plots.
. ^1 d( w' N& D" z6 F* T0 I- Ato setup4 C- ^; K4 t; S$ B2 z, Y  }
  ca
8 }* h: e3 A* Y/ E  setup-globals- K$ Y& x, D* j( x1 u

+ X+ S0 F- }" ~  N2 _9 C  ;; First we ask the patches to draw themselves and set up a few variables
2 e! f$ Q6 |; R8 G: \  setup-patches
2 U. Y2 g* x0 M$ T7 X9 [  make-current one-of intersections
, l& o& I) T+ q, A- s1 @! P' [. O  label-current' D/ R/ ?2 d9 V" U8 r: _
* |. `% w2 h' D) z+ @6 C5 Z+ Z
  set-default-shape turtles "car"9 W5 S& L3 a) ~7 E' J1 k# A( O: E5 t
' Q$ J7 y2 x- r0 Z* W7 x
  if (num-cars > count roads)8 c& x9 }  B- X- f# u
  [
/ M( H1 k' t' Z; ], k! w    user-message (word "There are too many cars for the amount of "
+ Y( f! j; s4 _# b                       "road.  Either increase the amount of roads "7 P& Y+ Y" U% _/ r
                       "by increasing the GRID-SIZE-X or "8 a% s+ E$ s% Y$ X& P3 z4 ]
                       "GRID-SIZE-Y sliders, or decrease the "
( a9 D# m* f; `- x. n! \$ q) s) ]                       "number of cars by lowering the NUMBER slider.\n"( U) O$ F- l; m0 l# U  t
                       "The setup has stopped.")
9 e7 \8 M$ i0 c0 L: K4 Y4 ^    stop4 ~  Q( a# `% O* }- K. a/ X$ U1 q
  ]
/ H1 A; m( l4 Z( r# I& X, x
; p, u. x$ v) j. O9 y  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
, ^9 F2 x7 W, h2 a; A  crt num-cars
8 P1 z2 z  K) Q' I3 G8 S: b  I4 [  [; a, W' r- p* Q4 ~3 `
    setup-cars
( T0 S& o/ R9 G) n    set-car-color
0 I& `- o  t! l% }/ i% u+ d+ w    record-data+ L$ j6 X. ]8 Z. s2 Q3 c% I
  ]
1 h8 H  z! H4 t# x
* ^$ H2 O0 _- Z# a. B  ;; give the turtles an initial speed- Y4 m# H4 }: R% b0 \' P8 i% g
  ask turtles [ set-car-speed ]
! F- Q' G# ^5 W) o8 o" E6 {4 D, `! g, K. E
  reset-ticks
% Q* w* R6 Q) z4 M5 r& Pend
- X( P0 W! R, R; ~& a5 ]$ J; B+ E) |9 j3 b
;; Initialize the global variables to appropriate values
8 m/ a$ S1 \# oto setup-globals- Z+ G# b$ K6 |- c& `
  set current-light nobody ;; just for now, since there are no lights yet
" P; P8 C0 @, Y  set phase 0% \$ J5 q  j# Q- ?. y2 ?! i% r
  set num-cars-stopped 0! z. l4 Q8 D1 P1 ?2 m
  set grid-x-inc world-width / grid-size-x% R9 H+ O8 i. @
  set grid-y-inc world-height / grid-size-y
  H' R' }' l) Z% V0 @1 ?7 [1 E" h- P% u; _& L. R9 ?  F
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
! V  x% y% a1 {2 W* T1 b8 Y  set acceleration 0.099# O4 L& ?# u8 {! o, y
end& j& l) d: T/ c+ O) _( O/ Q
8 ]! }2 c! A0 ^& e6 m7 _$ @
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
  I' |; R) g; \; j;; and initialize the traffic lights to one setting
7 j  f3 |: A8 m8 a& k6 T1 z! h0 Jto setup-patches0 Y$ e  T' b' v3 w) B5 e
  ;; initialize the patch-owned variables and color the patches to a base-color
+ Z8 b7 I. H/ K& H  L' _  ask patches; Q- ?* W' u* ~* O. R7 {, R' @
  [
( i/ a4 [% ?; y9 x* n    set intersection? false8 M% u! z5 |1 K7 [& f; J. H! W
    set auto? false
" f# j& N9 V- {9 ]    set green-light-up? true' P! b5 F) L3 i/ R6 I
    set my-row -1
# R# E) H) w1 u6 V  N    set my-column -1, ~, B$ A. f' |9 B
    set my-phase -1
5 s) I5 M- w$ j! t& ?3 Z' w0 v    set pcolor brown + 3
# W! G$ v! J/ ]2 D, p  ]
/ W6 I) X1 ^; ]( v& y% ]
& X9 B- r% P  z3 `: }$ h" c  ;; initialize the global variables that hold patch agentsets  Z! J: C  p& t
  set roads patches with4 g# G! n6 E" l  I# X$ E
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
/ I) d4 t* O- J, q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! F: I$ G" m: s% @
  set intersections roads with
$ f+ ]; \7 u' ], Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
5 U5 u  l- w( s+ j    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 z4 p- B+ d4 Y( D  P, t6 P/ [
9 f3 E; v; R( E3 h% M% _# A: A
  ask roads [ set pcolor white ]
3 g8 a, e8 T7 W: m% r# }& y' \    setup-intersections
/ [  Q1 K' `. t: k% Jend9 l3 U' g: L1 g
其中定义道路的句子,如下所示,是什么意思啊?! N/ V$ G2 k0 U" x7 J) s% j3 j- J
set roads patches with  `; V. `' x2 X. Q' e
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
; K5 Z5 O# U" n& X    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 ~; l% h) J8 l
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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