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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。
/ d3 }2 Y9 a3 B+ a& l( a$ l2 k* e4 Xnetlogo自带的social science--traffic grid这一例子当中,5 ~: W9 j! z" |; S1 @
globals
9 A2 A/ @9 H0 o5 m- ^3 m5 }# S' H[6 [9 o5 Z) B2 ]( i6 |5 d0 n$ q
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
6 i  a7 O1 x9 ]& g7 U  grid-y-inc               ;; the amount of patches in between two roads in the y direction  ]0 {' i6 M' Z$ F1 v
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
! h6 m# j( x- j8 y% k( `                           ;; it is to accelerate or decelerate
' y0 W* O1 g; F' L6 N6 k/ r: w' h  phase                    ;; keeps track of the phase/ L' X5 b; K% W% G8 D+ \7 s6 q
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
/ A* i8 a* t: R& S- G9 _  current-light            ;; the currently selected light% Q$ W6 Q0 L, }. k/ N  D

. P' M/ c3 N# h; V. ~- r. E  ;; patch agentsets
! b+ V7 Q6 {* K9 C1 l- O) n- v  intersections ;; agentset containing the patches that are intersections2 j9 ?( Y& f3 t5 b: I+ v
  roads         ;; agentset containing the patches that are roads
8 H# T6 I2 C, |3 m) K2 O  O! |]
1 |9 \+ ^+ C. W* v/ C4 U: a+ W. g( y: _
turtles-own
: x4 Y- v% ^, s' t% D[
- u3 m3 a+ M. {5 Z- l+ w  speed     ;; the speed of the turtle5 n6 w9 v5 B' ?' B1 z6 E6 A8 q
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right" m: I* J+ _/ n& {/ ~! H. B
  wait-time ;; the amount of time since the last time a turtle has moved
8 B8 A+ X8 V' v; k; g]  m9 \. H* M" a9 {$ Z

6 q6 u' n+ V3 S1 Epatches-own
* m1 ^  ~# M/ a' [- A[% c' u) l' E7 Z) M0 g$ m5 ?
  intersection?   ;; true if the patch is at the intersection of two roads
. F- h$ K8 y1 C  v! M% J  green-light-up? ;; true if the green light is above the intersection.  otherwise, false., i5 B% w% p& j
                  ;; false for a non-intersection patches.6 P8 V3 w' V( u* j
  my-row          ;; the row of the intersection counting from the upper left corner of the
3 T9 J; Q6 o; ~/ m                  ;; world.  -1 for non-intersection patches.
% K! c  v  e- n( j3 m  ?6 x  my-column       ;; the column of the intersection counting from the upper left corner of the
4 f/ B) ^6 p0 z; t                  ;; world.  -1 for non-intersection patches.
/ ~% K9 c2 ~, Z! ?9 G; f! m  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
" v; L3 n1 S1 F- `* o: K( h  auto?           ;; whether or not this intersection will switch automatically.
, l6 G4 |+ V) C                  ;; false for non-intersection patches.4 C  a1 A' t1 _+ f$ c6 H
]
2 a1 _+ E4 q. u
# w) \8 V0 |! s4 u% T- u; f! d+ i9 z- n" o
;;;;;;;;;;;;;;;;;;;;;;
" V, w4 ]1 k6 o( _;; Setup Procedures ;;
, R/ p' n/ \* |;;;;;;;;;;;;;;;;;;;;;;
1 C. X8 C) v0 w% h5 `5 i3 }7 [5 s4 Y" D9 o) b
;; Initialize the display by giving the global and patch variables initial values.% l3 m* Y$ c3 \: \
;; Create num-cars of turtles if there are enough road patches for one turtle to. c9 X" L! h0 s' `$ n" B8 [0 J
;; be created per road patch. Set up the plots.
; B- I; A8 b3 k/ W8 Ato setup0 o0 }8 N" A. ]
  ca! i: q( N4 ~, R, F) e8 N
  setup-globals, ^& D( N2 U  X+ a/ I
6 ?  ]# z# @" O4 x5 G
  ;; First we ask the patches to draw themselves and set up a few variables* e3 A; O" R- H  g# c
  setup-patches3 q7 d) D5 [8 l2 j  v0 _% Y' l0 V% M
  make-current one-of intersections8 ^& t+ e4 l9 I: q! \% Y6 ^
  label-current
$ l  k! G. `$ x& J3 o; o
0 v; c+ a3 ]& n1 [1 k  set-default-shape turtles "car"
  |7 d4 z1 i2 O8 d( p. n3 z- U1 m# k( t9 @% }
  if (num-cars > count roads)
2 S+ W7 {$ q' W: F  [
: |% Q& A7 x# B% r    user-message (word "There are too many cars for the amount of "8 E/ j: H/ ?7 n
                       "road.  Either increase the amount of roads "
. i$ t; I8 a1 H4 e5 ^0 W                       "by increasing the GRID-SIZE-X or "
7 ]  C: q$ u$ Q                       "GRID-SIZE-Y sliders, or decrease the "* \- ^( M' |& L* Q+ a; |5 r$ k
                       "number of cars by lowering the NUMBER slider.\n"; ~1 Z3 D" S* I+ l% `1 ?
                       "The setup has stopped.")
3 E9 Q! o. J( e7 s6 k6 x    stop2 N; s1 L# I: m, [
  ]' {8 t0 {- K6 z% A
) f# d7 @  y8 t' T/ l
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
& r3 g# K. D( Y: o- j  crt num-cars
( m1 j* T( l% Y5 c  [# T8 z2 ]* ?5 m& q+ a$ T, X; c
    setup-cars/ k1 T( v4 z; T$ `8 t2 d# @
    set-car-color
. `8 v/ m- I6 `6 l1 c    record-data
( E  F! I5 R+ ^1 |" S( f0 o  ]0 h/ u7 D% J; s/ h( m

( ~( q- }9 S! G. i  ;; give the turtles an initial speed
, C! [9 I/ @+ v# E$ e9 F' q  ask turtles [ set-car-speed ]
6 [3 ]+ _, B/ [  @
& O& B* o5 o  [8 c4 B  reset-ticks
$ s1 [4 U( v4 o: aend
, `9 ^- X+ O6 f% v* J
9 F' P8 e/ k2 ^1 c% m1 u9 `;; Initialize the global variables to appropriate values8 @8 {% N4 b; _! H8 M( z  r
to setup-globals
) X) O' P: O0 l9 v) n! s( I  set current-light nobody ;; just for now, since there are no lights yet
5 m. @- E/ j0 d- B5 [( b$ d) e  set phase 09 g. P$ e, }$ k
  set num-cars-stopped 09 a+ n# N7 B9 y' h. q
  set grid-x-inc world-width / grid-size-x
9 S! j/ ~5 h5 r% B" B$ c- [  set grid-y-inc world-height / grid-size-y
" S1 ], q+ H6 L4 `7 K- s& K- A- E, F; a1 i
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
; n5 w5 n1 O* W! @! E/ j; T  [( S9 l  set acceleration 0.099
" E) G8 o$ q1 X, q/ L3 oend
& J! Z' o; V/ v4 Y. O1 x6 h$ ?8 {3 U  k, p/ j( z( e" X
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,; e9 q7 \# D/ O" }3 x
;; and initialize the traffic lights to one setting
; _, e/ U$ M# b  a: t0 `# tto setup-patches+ R0 ]/ S/ \' \- d1 [5 f2 h- X
  ;; initialize the patch-owned variables and color the patches to a base-color( d# H" d# A  }+ D; f6 J
  ask patches
  f; [7 f# ?4 A  [0 S$ n, G" A' X7 X8 J& `% D
    set intersection? false
. N& Z& |7 a! W/ |; L9 {, ^    set auto? false! s% c1 Y9 J% E6 i
    set green-light-up? true; x7 B9 h. l6 S- s( s
    set my-row -1
) {0 W, O& V- Z    set my-column -12 D& R' `8 E2 h4 F' a
    set my-phase -1
2 z  e3 ?  y6 A0 y/ `. V: y    set pcolor brown + 3
! v! J' J* H5 a% ^+ r4 b  ]; Y: L6 c  H& n, w( `
* u: G5 ^+ x! [4 v4 o4 A
  ;; initialize the global variables that hold patch agentsets
3 N' G# ]6 O1 ]" Z7 B1 Y4 z1 G  set roads patches with
2 G( _1 B* w" O$ k' g& C- ~8 w    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- e1 C( m, s3 n( t0 ?9 q- R. A  L% w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ T7 ~  k+ K5 C. [; A
  set intersections roads with
. D. V7 a7 ]7 |+ T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and: a5 l7 e! u- `1 b, Y+ c
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( m9 M* ~! B5 Z) z; k% @' J1 v  g4 b3 {6 T$ x$ h4 h
  ask roads [ set pcolor white ]
0 V& v3 z* ?) K+ ^7 K- P/ ?0 }    setup-intersections& L$ N) `. q/ N% W, E! H+ A
end3 b6 P/ W% @( a( t! a
其中定义道路的句子,如下所示,是什么意思啊?
$ `6 ]2 G) W5 Y. o6 d+ S- A set roads patches with
! A5 g6 O  V& k1 @    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 L& G- z' K; j/ {& R% y8 K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 [, _8 ]- D7 O* }5 X% {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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