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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。$ j) Z2 U( P' ~, L4 Q. Y& x/ ~
netlogo自带的social science--traffic grid这一例子当中,
7 E. q3 a5 {2 m  `/ vglobals
( f% H* C! `9 m! T: v: H6 H9 Y[
1 ?0 G1 L, Q9 e. K  grid-x-inc               ;; the amount of patches in between two roads in the x direction
8 h; K6 W9 }4 d3 `  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 l. E. G& W4 R4 O8 ]3 r! N  i0 b; T  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
8 {' a. m, ~; E                           ;; it is to accelerate or decelerate
5 Q6 u' ]+ |9 P4 F' K  phase                    ;; keeps track of the phase
7 k4 ~. s# B! N+ @5 W  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
7 L8 J7 J' d6 S  current-light            ;; the currently selected light  p4 C4 `5 o- v( S. i( A9 X

$ y5 S- H7 m2 @) Q  ;; patch agentsets
% T4 D. i& P. h' ]. c  intersections ;; agentset containing the patches that are intersections/ r! {; F" W2 D
  roads         ;; agentset containing the patches that are roads
( T# r. Q# i: G* {* a$ m]
8 G1 b7 Y3 X( P; K! M
1 B( M9 M2 u- N) L) D! Jturtles-own$ u( {1 I; i( ^4 s! R' o
[0 D( b" P- f" A5 \9 Q
  speed     ;; the speed of the turtle
1 |$ o( U3 o$ M4 d% L# J  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
- U+ j" B& q6 H" P/ i5 q  wait-time ;; the amount of time since the last time a turtle has moved
) m2 e* b3 L! x. _) `8 E]
/ a# T. c) D9 @) ]6 q# b5 }! c, [, X, w( H: [. S
patches-own) p2 b! s. H% E( t4 r3 ]
[( H- G, h; g  \6 o
  intersection?   ;; true if the patch is at the intersection of two roads
" I1 V+ {4 m* z  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.* x/ ?9 F$ ]' N1 F' a& k0 X
                  ;; false for a non-intersection patches.
3 ~/ K9 V, |3 a  my-row          ;; the row of the intersection counting from the upper left corner of the
8 A" C5 I- G2 n/ \                  ;; world.  -1 for non-intersection patches.
; W) ~0 l: k  ^$ b  my-column       ;; the column of the intersection counting from the upper left corner of the5 k7 A8 T5 z% H# V8 O
                  ;; world.  -1 for non-intersection patches.
" ]( h- c& h6 p+ L  A9 F  w  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.9 n6 ]$ I  L5 Y1 s+ S  h# B4 b
  auto?           ;; whether or not this intersection will switch automatically.. F: p: B2 R$ i9 j% M* X5 p0 z2 p* D; T
                  ;; false for non-intersection patches.( q3 A) c1 K; z1 Z: H! b
]
% k( d" p" o! h- Q; y+ j3 p* Q5 ^) p& L' T: {7 g( H
# B+ h# H$ R" i) c3 D; {
;;;;;;;;;;;;;;;;;;;;;;7 ?4 o* _- f  k: e6 h/ ?. R6 \
;; Setup Procedures ;;
% y+ d( @2 @& g;;;;;;;;;;;;;;;;;;;;;;
* C/ r. c3 }0 a5 N& S8 v3 b9 J0 Z8 ?5 H  }, {' T. P
;; Initialize the display by giving the global and patch variables initial values., D5 I4 ]6 ?# ?( Y4 H' q
;; Create num-cars of turtles if there are enough road patches for one turtle to
3 G! v* q) W: Y5 n  Y;; be created per road patch. Set up the plots.: G$ h! R9 C# D: F: _
to setup" e' c' I5 E2 f6 C& s: a/ L
  ca
1 c& X. d$ S2 M! I0 ~' N  setup-globals
1 d7 N8 a- C0 b8 }" P( c' o# d% A' Y4 z4 \" [9 U. _
  ;; First we ask the patches to draw themselves and set up a few variables
1 q6 |( |' n! {  u+ C7 o  setup-patches
' o( w& u- h* f9 t4 s$ x8 k  make-current one-of intersections
6 p. Z* ?& |# B+ {4 O. I  ^  label-current# |  |* x. v8 o: i

4 D. Q& u" G& z% f! S  set-default-shape turtles "car"
$ L/ n2 J0 [* s/ e2 \& Q4 q8 l; Z5 o& M0 B, l  M3 l
  if (num-cars > count roads)
* m$ P/ u4 ?* Y; ^  [6 C- O3 F7 F( b  k
    user-message (word "There are too many cars for the amount of "
/ d4 t) e: p* e3 P! [* ^* G  S                       "road.  Either increase the amount of roads "
1 m4 n. t( P; K# u+ ]                       "by increasing the GRID-SIZE-X or "
& b% L3 d6 Y& {, Q0 X                       "GRID-SIZE-Y sliders, or decrease the "
5 [! p3 ~" j9 o  T. C, a; D. |                       "number of cars by lowering the NUMBER slider.\n") V9 P6 u) X( E' U3 P
                       "The setup has stopped.")9 K! }4 c2 r' \0 m5 @! n2 R
    stop
2 P8 _) T4 m2 r4 N( M  ]  T% F+ l. i7 z6 a% j
: @3 V% m7 W. k* f% p. C
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color0 J. b4 h3 |) y1 A$ F+ w
  crt num-cars8 a# P- E7 X5 B; u& N
  [- q& u9 V; w5 V$ H$ p/ i0 }
    setup-cars) i  _9 o# W) f% k* t# {5 }8 q. m
    set-car-color
7 X: [# v. A; F    record-data, z, H! |/ J2 b6 p. \, l( U' y# }$ y5 e
  ]! z1 T. Q" ~/ v: e8 ?. n0 b
# y7 N& D) H4 T9 O  A
  ;; give the turtles an initial speed1 l# v8 o7 t: M, q9 s4 A
  ask turtles [ set-car-speed ]% A7 g2 z" `6 ]( Z; B! {
0 |6 Y/ i# g$ h; @' T! ]
  reset-ticks/ p5 O6 t" f$ r9 ~- A: N2 l1 L
end$ p- J8 O8 H2 w* H4 K+ S7 a, ~

4 O- q9 Z. j' R$ i0 j' t& T% j6 b;; Initialize the global variables to appropriate values
; t6 W/ s  k2 L' Q- Pto setup-globals
/ W( X  J+ W) }& Z$ @  set current-light nobody ;; just for now, since there are no lights yet1 s/ W3 Y" P/ s: h
  set phase 0
4 U& U: J5 w0 b- q0 B1 \  set num-cars-stopped 04 q( }1 i7 h) T5 o
  set grid-x-inc world-width / grid-size-x
! J, o5 T/ j5 b5 Q  set grid-y-inc world-height / grid-size-y
4 |5 d! M+ V! X6 r% T8 I2 N4 `" [$ a9 S6 A% A
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary# q# C1 x) j* O; G
  set acceleration 0.0996 ~& E0 S$ r+ }( n4 N( W
end
! m0 z. \8 o* _8 V" r
1 Q6 N. h1 B, n% ?+ ?9 |;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
( L) l: ?9 `0 q# ^;; and initialize the traffic lights to one setting. h. W+ r4 U. H  A  j3 a* s: N
to setup-patches
- ^/ ]# U1 \9 H2 x  ;; initialize the patch-owned variables and color the patches to a base-color5 c+ S9 [: `5 G2 J' B
  ask patches. N1 R2 b' K  N& ~% W
  [
' [7 E+ G; C% o, e+ _5 I3 _2 ]    set intersection? false# a' F! e: S! Q7 n) h* Z+ w2 t: ~
    set auto? false+ ]- S' A) c  `4 x5 S) j3 `
    set green-light-up? true
  `) j& a+ i' A* M  W    set my-row -17 v3 a& J0 V+ `" g6 R2 b6 U: H
    set my-column -1+ L% o# o% O4 I( o
    set my-phase -1# b- A- p- s. ~
    set pcolor brown + 3  v" Z1 n0 l& ^& }4 ~; z
  ]* {+ x% d  _9 h6 Z0 N" A( ~& X6 h! T
  b, o% g8 v% t% m3 \, L* l
  ;; initialize the global variables that hold patch agentsets* Z5 O6 }5 r: ?
  set roads patches with2 g! P9 E, {8 B: K
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) v$ [1 y, B) I9 |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% n) e% B- e6 U. t- c; D! _- z  set intersections roads with* x4 d. G+ k6 }  k- h' R6 ^8 ^0 R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
) A1 ?* `" s. n! g! y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) p5 S- H/ h5 b" @8 E8 r. }
! J8 h& S$ b% T- x% ^: ]2 h
  ask roads [ set pcolor white ]
" d2 s# Q4 C" r" {! g' P- E    setup-intersections
; N( F+ i( j0 Eend
. r) }6 _- `7 {1 R6 o其中定义道路的句子,如下所示,是什么意思啊?
" P7 |- ?) v5 A0 Q/ U5 q5 ^ set roads patches with
$ d: i+ R7 S+ E" U    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 [/ i; C2 k; T! |$ ~4 z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. q( o3 f/ v- P& H1 d# u) F9 ]
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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