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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。! ^: V+ r# O5 y/ m. j8 Z! O( }! |
netlogo自带的social science--traffic grid这一例子当中,6 {/ E4 {, d& M" z3 `
globals) Z9 W  _$ K; Z' }- h
[
' O2 [" F2 @+ \" n  grid-x-inc               ;; the amount of patches in between two roads in the x direction+ [) r% P, m$ m  d9 C0 _! U- ?
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
' \) G, `0 f4 w) w; i  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
- |; W8 A. U" `* Y# f                           ;; it is to accelerate or decelerate  D) N4 J6 w1 L  M3 _/ y
  phase                    ;; keeps track of the phase
& T* W4 k1 C8 _8 ^  j' L  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
& c+ T1 Q; k+ u  l  current-light            ;; the currently selected light2 A/ @, f0 }: j
' o) y4 V* a/ b6 `5 y* L- |
  ;; patch agentsets
' h" A# T2 \* T+ |( X4 O- c  intersections ;; agentset containing the patches that are intersections
, V5 @9 Y* P+ b. }- X9 F  v  roads         ;; agentset containing the patches that are roads
# u* S) @( ~/ ^9 n$ _]
' r" F8 u; z7 a, k- a
5 P/ v6 Y) j- ^! |/ K* T/ \turtles-own9 ?) u. r  r4 R8 I( f
[
  G8 p/ D9 B  f( [  speed     ;; the speed of the turtle
6 V7 C- }8 u, z  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
+ G$ E9 D+ |$ L/ i9 R0 a4 n  wait-time ;; the amount of time since the last time a turtle has moved7 w9 ^5 ?- _. D6 I! M
]
3 r+ s$ L1 Q5 y/ ?8 X8 s# P# \2 F  Z3 l  X) r
patches-own, e+ P- K1 ?' x. {/ ?
[
, E- O; r" m2 n4 S% @9 G  intersection?   ;; true if the patch is at the intersection of two roads
+ t& E: l; U6 V6 `  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
  V5 b0 C# n6 a7 A) Z                  ;; false for a non-intersection patches.
) y+ u' p9 F2 z$ ?& A8 X* I$ p  my-row          ;; the row of the intersection counting from the upper left corner of the7 x7 H6 t5 L3 k% _$ k5 x8 ]
                  ;; world.  -1 for non-intersection patches.
2 G2 u8 [# R! p2 ^- _. {  my-column       ;; the column of the intersection counting from the upper left corner of the
9 W# ~' t' ]- D4 q7 B. c                  ;; world.  -1 for non-intersection patches.1 L+ h1 R' O+ r5 b
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.% X4 _* T+ Q: J/ o$ O1 X- Q$ k
  auto?           ;; whether or not this intersection will switch automatically.
& R( N) |+ ~3 W2 W$ _( e8 {                  ;; false for non-intersection patches.7 Z3 \8 d1 s; l! ]& N- n( R4 j
]
1 d0 @  F1 G. [
6 p7 `) ^+ l" q, N5 f
  l# \+ h/ k  L7 ^9 N) c;;;;;;;;;;;;;;;;;;;;;;) y2 @( k+ ?! }2 p, X3 F% W" W9 B
;; Setup Procedures ;;( y0 u7 ^5 E' j  K/ T
;;;;;;;;;;;;;;;;;;;;;;; G( z* Z( F* g
0 f* f8 O% {# D, V8 J5 m
;; Initialize the display by giving the global and patch variables initial values.
1 N; V; h  Z+ m;; Create num-cars of turtles if there are enough road patches for one turtle to
4 P, Z2 c! w- D# r$ U! Q;; be created per road patch. Set up the plots.
  ^* ^- \3 a% W' B7 T, @9 F+ Uto setup" v) f, @9 t  u6 s% @  \
  ca' W' Y5 f- D$ F/ ^
  setup-globals
1 d5 X! p& L$ |' J3 ]) E* R
( v+ m. l; J% z" q  ;; First we ask the patches to draw themselves and set up a few variables' J. R6 U( h' p9 y
  setup-patches" @9 P/ i* d- L
  make-current one-of intersections& h! h" L" j$ r0 ^- C
  label-current
2 @" \# g2 a: @' U3 l( Y. A/ O7 ^" A; l2 r% `4 j
  set-default-shape turtles "car"% A' L; e$ H2 w) Y- r( \$ w
# O6 s* R8 f! y% [- t
  if (num-cars > count roads)
0 h4 B) \7 u3 {# y3 }  [5 H. p# t$ n0 a7 l. f
    user-message (word "There are too many cars for the amount of "8 G( R3 C: f: K" t( R. @: O4 v: ^
                       "road.  Either increase the amount of roads "
/ |5 B1 E  h! Y* e- X0 J                       "by increasing the GRID-SIZE-X or "8 n3 h3 {+ A9 I9 k
                       "GRID-SIZE-Y sliders, or decrease the "+ S( y7 B- A3 `- M. @/ ]2 W+ C
                       "number of cars by lowering the NUMBER slider.\n"0 @0 b( s! p5 |7 G6 U: |
                       "The setup has stopped.")
% d; L) b/ Q( J1 m/ H8 E8 [$ E9 C    stop* I2 h% `5 \9 f3 u0 ]% j0 Q
  ]
0 d4 ~) e. C5 c" o0 a9 j5 b
9 |' k% @' b  P: R  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color1 {& f2 @: s7 C* J: d
  crt num-cars6 o6 ~& b# U( M: c. ?
  [* O* X0 c, j8 G
    setup-cars# N+ x  {; ]5 t6 }  E3 o
    set-car-color
5 J5 k4 t) L$ h4 D    record-data
& o1 x' b5 l  b  ]
% V% K. _! L/ X
' M" r2 v: Z5 |3 `6 R- ?$ B% b. k; ~  ;; give the turtles an initial speed
6 d9 Z" u2 g& Q  j. }  ask turtles [ set-car-speed ]
3 @/ o6 o" d5 V: |$ h' x0 w2 Z+ `/ m. q8 m7 K7 f5 h3 o, G' M
  reset-ticks' `/ H/ m2 ?/ |* y' t
end
: R3 T; ?% S2 Y6 `& Y
* e- j' ^2 n( ?' D1 d+ m: |;; Initialize the global variables to appropriate values0 l5 \0 d( g+ q  V( p9 f
to setup-globals+ V. S. l* M9 b7 k& e6 a* S
  set current-light nobody ;; just for now, since there are no lights yet8 r. K2 h* o& V7 u- h% S5 a
  set phase 0
2 a. m& e% W* q/ D% F: |" B& e  set num-cars-stopped 0
$ E+ N# D$ }. P, Z; S  set grid-x-inc world-width / grid-size-x7 @, [/ T4 n  g) Y+ w
  set grid-y-inc world-height / grid-size-y
2 m. j& s3 M4 o  N0 Q1 b( G; p
2 o( x0 H  w) A$ f' X" \  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
7 q; ^4 J" X' h  set acceleration 0.0991 E) [" e' h+ P' A
end
, p/ v' i# i3 k% ?
+ `7 Y. c/ r5 E+ ~;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
  A7 |" ?5 }# x! }! g;; and initialize the traffic lights to one setting0 D* `0 C+ ?4 w" J7 r
to setup-patches
  m* p% [! O2 \! x, Z  ;; initialize the patch-owned variables and color the patches to a base-color: ^0 \4 N# I/ B( s: W/ ^" Z& C0 H
  ask patches
' g' z8 F3 O$ Z5 m: U8 X  [% m5 N  D8 T. p4 y0 m
    set intersection? false5 S8 ?, t& O# |, N
    set auto? false
" {5 G3 J" |* y" X/ K    set green-light-up? true
9 h& \. h+ {. T# N1 O    set my-row -14 l6 _; N5 A8 z) m' X
    set my-column -14 O6 N4 r$ m' o2 Y
    set my-phase -1$ J, U( s' i8 W% X- u" J
    set pcolor brown + 3, _/ O, S2 h# W. P- z  Q* q& h
  ]( Q- Z5 L- K) y( n  s- g- U( G

0 ]/ `9 I% A) O4 n# j  ;; initialize the global variables that hold patch agentsets: W: s$ `; \9 X) @1 P
  set roads patches with
/ Z2 I! @7 |" j4 U( r: S' z! N5 i    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 M% J4 \3 A/ P+ {' ^: h  Y" Y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& v( u6 E1 R( F0 R! A2 ]  set intersections roads with
. r) k+ T9 z. G; H# o* [2 B2 f9 T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
" x! N0 O/ r" B* R    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) s/ Y# c# r4 J" c' _+ D. _
! R! r( x! v6 _- E  ask roads [ set pcolor white ]
. ]/ X; m" z/ s    setup-intersections
% `+ S: w* v9 Cend
+ m# f7 A" U* o其中定义道路的句子,如下所示,是什么意思啊?
8 O: u' V- D, K# W& u% Y, S( \ set roads patches with
5 A- U; t% f# }9 ^7 m    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 I$ F# ]3 V$ G! `  [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( u3 b  h+ U' K7 o" E) k6 J: z8 L* P
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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