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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。
/ s4 V& r8 p4 Y$ J& @; `netlogo自带的social science--traffic grid这一例子当中,
5 l' ^/ e- g( U4 Kglobals
- ^3 E3 t1 x. q( e9 d2 r: O[1 E$ e! |( v1 A" q4 K" S
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
4 x/ d6 c  H* O+ Q  grid-y-inc               ;; the amount of patches in between two roads in the y direction
, s- m  t; o/ ?; E; R  k3 W0 u  acceleration             ;; the constant that controls how much a car speeds up or slows down by if1 K8 Z* d) |& h3 g( m- D" N
                           ;; it is to accelerate or decelerate3 t0 }" V6 j% F- k" _. ?
  phase                    ;; keeps track of the phase
8 d( y& y$ _; ^  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure" ^) o! H+ _8 ~3 J/ W$ Y
  current-light            ;; the currently selected light
& l; v) ^. N0 o5 Y, H% H9 [' p0 B6 E* s. }2 o- Y# w
  ;; patch agentsets
4 _' G6 F$ w3 z  E  intersections ;; agentset containing the patches that are intersections4 S- }" g/ r1 \
  roads         ;; agentset containing the patches that are roads
: W- [/ o/ `9 y]% f6 q: d  I1 K# A  F2 [" B

  n$ _. v4 y0 Nturtles-own
7 E- N8 j3 `# F& `6 I[
" g/ a' Q# I0 x* m8 h& n; B: L% D! W  speed     ;; the speed of the turtle2 f& l- Y/ K& ]+ ^& N4 P
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
8 B# C/ `+ J& r/ {" O% R, ?  wait-time ;; the amount of time since the last time a turtle has moved
3 S- X- R$ b: O]" ?/ F* |9 g9 g: x* I& p; V
8 v# f. J. @) Y
patches-own
% v; [! \1 ]6 }- P[
$ N' Y1 T4 x) A" O* B6 q- h' L  intersection?   ;; true if the patch is at the intersection of two roads
% r- K; W0 }0 j. ]2 o  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
+ N9 L* ~" j  Q( V                  ;; false for a non-intersection patches.
! z1 Q# }8 S. u3 Y1 B7 D5 N0 ^4 J  my-row          ;; the row of the intersection counting from the upper left corner of the, O# @2 _  W- |  w$ H0 b
                  ;; world.  -1 for non-intersection patches.
1 E4 }4 Y* C5 \6 `; z5 X9 i  my-column       ;; the column of the intersection counting from the upper left corner of the. q2 g& R, h7 }
                  ;; world.  -1 for non-intersection patches.( X2 U) v0 b. I; A
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
9 R! H  C& g9 H6 Y6 H  auto?           ;; whether or not this intersection will switch automatically.
* Q( {2 X4 [) X1 M6 u                  ;; false for non-intersection patches.$ X: @$ N2 E$ `! y7 i2 X
]
* t2 u: c5 j4 k' A3 A! T# A4 L: Q
, S9 v4 E6 R* `( ]' ]: S2 @5 R% z! _. k2 |" {
;;;;;;;;;;;;;;;;;;;;;;
! Z- a- ~9 M( w4 r+ u" ~( c;; Setup Procedures ;;
8 s! q- L1 f" ]7 {; x! `;;;;;;;;;;;;;;;;;;;;;;1 s7 w8 |, b* `& e2 l; _
8 X: d, {+ Z$ J2 ~; {; b* B# P2 m  o0 a
;; Initialize the display by giving the global and patch variables initial values.8 }# o3 |  u: j: t/ h6 ]
;; Create num-cars of turtles if there are enough road patches for one turtle to
$ q, h  a" c5 r;; be created per road patch. Set up the plots.
$ m- u* H  J. k! hto setup4 r  W% b6 ?% H$ d
  ca  Z& `- ~/ w, i& O
  setup-globals
, f1 k0 C; ]$ ?( G
3 O9 A" [/ T, W3 p: C9 m4 e  ;; First we ask the patches to draw themselves and set up a few variables
6 H3 O. J4 t" z& T* ]; j% m; _) Y  setup-patches
+ [  v4 w/ j. T) e  make-current one-of intersections
6 S* i4 E* e- {1 h$ e  d  label-current( i/ Y! I) U' L- e
. y1 [; S  L7 ]7 ^2 M7 O
  set-default-shape turtles "car"
; J  Z2 d% A/ Y2 Y. A$ P6 _# F( b
  if (num-cars > count roads)
" \# e$ g% p$ I' P" l6 T( ~  [
# Z% a% Q) O/ j! r- Z7 E+ |1 Q    user-message (word "There are too many cars for the amount of "
! @# E; W; X5 U/ n. N6 `                       "road.  Either increase the amount of roads "
4 @4 ]1 q5 d, }7 V( b                       "by increasing the GRID-SIZE-X or "+ |1 c' O0 x' K& o* E) N% v5 L
                       "GRID-SIZE-Y sliders, or decrease the "
( ]5 z; Q, p- a- q2 I  G% w                       "number of cars by lowering the NUMBER slider.\n"
% ?$ i8 o8 f) k7 D, `                       "The setup has stopped.")  d9 W( o+ K2 A
    stop
  x0 x1 P! |) @+ k  ]7 z. b/ U' H* T) F- g  R

# T% X3 b# L5 u0 o6 P4 D, e, e! S' \  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color1 B+ x. [6 g1 A" P7 s$ z" }3 H& r) g
  crt num-cars: |- _9 E1 X4 v% B8 C
  [
! \4 e! ?( a, z0 H* w6 n3 n    setup-cars/ J' [/ Y$ l7 R" b
    set-car-color3 a( o" {! ?& b& s
    record-data  x6 v8 Q8 \3 v# X  H
  ]8 _' D  [- a( ^( z6 J

# m4 c6 @) Q- b; O; Y: ?2 s% H5 p: y  ;; give the turtles an initial speed
' b$ N. K/ _# ~8 k2 Q: u) C  ask turtles [ set-car-speed ]
0 i  G" A: H& J7 I3 F. {+ g, }( j5 b" U) Z
  reset-ticks$ U* E( P" N! B  A* `: E) u
end
+ i/ q8 ]4 p( ?* E' h1 A9 d
4 s% `0 n" I- l0 S0 c% [0 e;; Initialize the global variables to appropriate values/ x9 L4 F: l5 B7 A+ e1 V
to setup-globals
! c' o/ H# H, I3 O" D  set current-light nobody ;; just for now, since there are no lights yet
2 X: o: H; Y3 `, W% A  set phase 0' E  U/ [9 y) p$ _! e" H/ p- n+ a- y
  set num-cars-stopped 0
: R+ Z5 j, `/ j5 V8 B  set grid-x-inc world-width / grid-size-x
9 g2 X: ^; S: X. W# L  set grid-y-inc world-height / grid-size-y
) _/ N( Y8 j+ E' T6 ~4 K- r: l4 {/ x  P
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary1 q4 P. |3 Y8 u! c
  set acceleration 0.0997 y, l& I9 m% Z' q% c
end
6 Z3 F( l; C8 S5 i( {1 g' a! m: u5 i* e. [' X  \7 {
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
) u4 s7 J- t3 z( s;; and initialize the traffic lights to one setting) x: r4 M( F- Y5 C
to setup-patches
6 `+ x7 e, i" A0 ^0 g" z* c  ;; initialize the patch-owned variables and color the patches to a base-color
: m7 K( n7 k) n3 w  ask patches, {7 @( B2 w1 T- A. H
  [
  l9 z* k4 ~- {7 I8 X4 n    set intersection? false
0 K6 R# S% y, l* b2 V( d    set auto? false; }; u/ e9 x/ ~+ V/ Y5 l
    set green-light-up? true# I; a  E( L9 _- u+ R9 C1 z
    set my-row -1: _2 U8 H, ?- D2 v- |. g  n
    set my-column -18 i; C: ]/ b$ Y1 p7 d
    set my-phase -1
0 s0 G! R! Z2 ?7 N5 j4 c    set pcolor brown + 3
! v, D( f' g4 \: x  ]
1 K! x5 |5 D! F* Y! M/ ]
" g0 M" M& L1 L) y/ v# u  ;; initialize the global variables that hold patch agentsets
! H4 K4 C) U) k5 [' @  set roads patches with' |- |- P' W( Q% A
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 z2 r2 `; ?& {" A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], T: n1 V! }: k& x4 N
  set intersections roads with
4 F9 ^$ I3 ^6 t+ D1 m# ^. T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
8 W. a: x6 p' k% i* ?9 I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 A" E+ U% n: S- {' t8 P0 z' L3 d* ?
  ask roads [ set pcolor white ]
; s9 U' g. @' M4 H* r7 H7 t    setup-intersections
9 x5 p  S) B1 t" Z5 y! Yend
) ?/ U3 Q4 W2 ]) X其中定义道路的句子,如下所示,是什么意思啊?
: B1 h% z1 i' I set roads patches with* _. ^4 \8 ]/ y: S
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or; V' O4 l, k( d) l
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# U/ X) D( ]. ^2 `. M
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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