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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 z+ o4 _2 Q3 `0 X
netlogo自带的social science--traffic grid这一例子当中,! o; H+ r7 [8 P4 T
globals. O) {* p) v! o1 |( n# I5 j
[
, C4 k/ g. a. {$ b* t  grid-x-inc               ;; the amount of patches in between two roads in the x direction* V) X  @7 U  d! J1 n
  grid-y-inc               ;; the amount of patches in between two roads in the y direction+ W- S' S  H+ g: F6 r$ @5 d# I" `
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if9 z; H. w& z- g9 N/ v, h+ F
                           ;; it is to accelerate or decelerate
' u+ s/ R- W6 u7 B  phase                    ;; keeps track of the phase
9 ~0 P2 E: L$ h- O  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
" k  ^# ?# O7 |4 B/ x- E! A/ P$ G" D  current-light            ;; the currently selected light# ~1 a. R9 W( n; a! x# A6 d

0 C6 _" v6 c6 ^9 g2 d4 ^  ;; patch agentsets  p) S  J" x  F3 x+ K% v
  intersections ;; agentset containing the patches that are intersections
& H- n% P' `9 T  roads         ;; agentset containing the patches that are roads4 i3 w) C- D5 H8 M; b+ ^, D
]: g& I  ?. ?* ~- r' x

4 \9 ]% I9 z+ x6 H0 Rturtles-own
& E/ \3 @5 u0 K3 ?; v: N* L$ F. K( i[
4 E6 v* R4 d" r( _  speed     ;; the speed of the turtle
! O! G5 [' E# L% g+ w) N  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
; t" M- @" ~. {% s  S7 V  wait-time ;; the amount of time since the last time a turtle has moved
: v7 O0 I8 T. P( o) B% Y2 e]6 M. D/ g+ I$ X2 T3 ]) N  T

/ y+ u% _- {& H  S3 ]! _/ ]+ R# bpatches-own# K+ q) t' M2 _3 y
[# k8 Q/ e  X# `5 X; c
  intersection?   ;; true if the patch is at the intersection of two roads) e, G2 B, P+ H- V" c, J; K
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.: \- X$ s/ d2 K- X- V" o
                  ;; false for a non-intersection patches.
* U& |- g2 l7 Z  my-row          ;; the row of the intersection counting from the upper left corner of the8 S6 \* Y' i: B( J& q& E
                  ;; world.  -1 for non-intersection patches.
: R( g8 ]9 Y9 T+ \- j  my-column       ;; the column of the intersection counting from the upper left corner of the
% u. C$ P% L  U) V' T  m                  ;; world.  -1 for non-intersection patches." s6 u2 w5 L" v1 J9 |# z" E
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
7 B  r+ T+ q4 B$ Q) c, G, k  auto?           ;; whether or not this intersection will switch automatically.9 ]5 ~7 L' K, g$ d! G* X
                  ;; false for non-intersection patches.: L4 H$ y( n: Y$ W
]6 g7 ~$ j( B. u  q& ~: o
6 Z  a# V$ T7 q+ `. q% {
) C/ r9 f6 t6 N  S* L
;;;;;;;;;;;;;;;;;;;;;;  e: D; |- P5 ^$ E1 @
;; Setup Procedures ;;. L* r* w0 w, w
;;;;;;;;;;;;;;;;;;;;;;& J& C+ F# r# z
7 h' m- I# |+ B3 F/ f. u# T0 L
;; Initialize the display by giving the global and patch variables initial values.
! z5 j+ ?" F' q9 y9 |1 c" Q! y  N3 B# c;; Create num-cars of turtles if there are enough road patches for one turtle to
3 }( |- _1 o8 y, g5 s- c;; be created per road patch. Set up the plots.* ~$ \% o- }, A  [' }
to setup3 p" Z: N: a$ k# o1 V- E
  ca
0 o; A# d. N/ V  setup-globals
4 Y. T) Q- i% C8 d" J0 X, G
2 z9 ?0 }3 M3 q5 W  ;; First we ask the patches to draw themselves and set up a few variables
. s5 e5 S1 I! x# \6 U  setup-patches
- p2 H2 j. C  k6 {" ]  make-current one-of intersections/ k# k" |) C/ h8 l% v  a) U
  label-current4 r- d$ w: M% Z- x2 _
) V4 Z1 ^/ e! C+ h  S- v# U
  set-default-shape turtles "car"
& r5 |' g6 }( s  Q. v: P$ U5 n2 r5 t9 z$ l& p7 r* V3 M1 X6 W
  if (num-cars > count roads); q$ m( n6 t9 N
  [. z5 `& L( D1 Y1 l
    user-message (word "There are too many cars for the amount of "
( s3 x  |3 M) w# f5 h                       "road.  Either increase the amount of roads "
: Z' s4 r) G' F; @                       "by increasing the GRID-SIZE-X or "; r8 K0 P. }+ p
                       "GRID-SIZE-Y sliders, or decrease the "9 t  a* K) x! y2 N
                       "number of cars by lowering the NUMBER slider.\n"9 U6 I- _: S3 [/ }- a9 T: y" `9 c
                       "The setup has stopped."): a. Y- d: V( g
    stop& V9 ?: U$ F* X% ^* Z  R( Q% E7 T
  ]4 L* U  p4 Y3 |! O& w, S
! Q) L6 o+ q# Z. }$ R* H
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color# Y4 _% O- ]' e3 b
  crt num-cars
4 S1 _$ N. t7 q/ }  [& W" c2 o. b, w
    setup-cars
" Q- J( e9 U* S6 z! m+ H    set-car-color
$ {! ?) G# X( y. e( x; j    record-data+ Z/ H( N) z5 c! I, H+ r. t; z
  ]
+ O) b7 {: z& R: Y
* d5 Z( E2 o- F% |# q( ]8 H  ;; give the turtles an initial speed
- a+ H/ C$ M) r& a5 B  ask turtles [ set-car-speed ]
- D4 ]3 J$ y# x& j* z- `/ G" |( V3 x" @
  reset-ticks
3 x7 I/ ~- d; I4 Cend
, Y. y. z- _) g5 U) [$ x
  w3 c) W+ d2 ]7 c% A;; Initialize the global variables to appropriate values$ ]' d, d: R! b
to setup-globals/ P( A9 e9 z+ n3 T  Z3 G
  set current-light nobody ;; just for now, since there are no lights yet
  |/ Z/ ?: W# d, D7 K& i  e  set phase 0
" c6 p+ C: k$ U5 I& O6 j  set num-cars-stopped 0& @+ r6 @' ~+ c6 Y+ Q
  set grid-x-inc world-width / grid-size-x
6 i1 T- {# P6 f* _) M2 @+ c  set grid-y-inc world-height / grid-size-y
6 I0 Q% ^2 E. G; {& U- w5 p+ a- t! ]) v) |: v
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
2 n$ [( J& S0 g' v  set acceleration 0.099% z/ W6 [; [% s4 B/ d8 n3 n& U
end  j6 z) Q3 p6 N. {* o

& y9 e7 [  P2 n3 J+ N* Q0 U;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
; W7 Z6 a2 Q' e3 X2 b, j7 c  V;; and initialize the traffic lights to one setting
- W# @# ]# F* T$ S+ bto setup-patches
! J+ S% i( k; W/ I, N7 U% N6 L0 Z  ;; initialize the patch-owned variables and color the patches to a base-color
  z  J  k: K: U: _4 y( O  ask patches/ a6 |  w$ S- _$ [; @* p
  [2 ^3 _; w3 |$ V6 p1 T' X
    set intersection? false
: h6 P' i5 r% X5 i    set auto? false
  }& b2 ?' d* X, d* ]: v, @& }$ [    set green-light-up? true
1 a, R4 L+ S! J% J7 Z; P# u    set my-row -1
! J/ L3 {1 L& t  A  U* X    set my-column -1
) h7 k/ ?* }: b    set my-phase -1. r9 A9 C. {9 _1 R1 q& S+ K+ x
    set pcolor brown + 3' Y( o+ i8 ?9 S- U" [5 V
  ]
- M7 m5 e0 O' z/ S
; S) f9 \8 V* }8 I- I! F  ;; initialize the global variables that hold patch agentsets
9 x0 o4 V) w& g% b  set roads patches with
  O2 z' T3 z: E3 `0 X    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 \" a+ W! W, j9 @  F' \
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& `5 d6 s$ ]& E  set intersections roads with5 n1 K; T1 _1 D% {) |
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and. ~; q4 M/ \, f; H8 l
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 i! }& L0 _" _& [  y

- O# L2 t9 ^0 w  ask roads [ set pcolor white ]
2 i  p2 D& G1 b$ K  l$ M    setup-intersections% \, t, S' S$ S- d/ S/ u
end" r+ L3 G6 C3 z! s5 \9 }
其中定义道路的句子,如下所示,是什么意思啊?. D* c, ]) \3 `; Y0 E" ^
set roads patches with
! t% C" B6 ]2 L5 _    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 Z% H- S/ y! s; M    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  D+ B0 i( Y  s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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