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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。
2 ^( s3 Q& `+ T9 _& E* g  M8 t" rnetlogo自带的social science--traffic grid这一例子当中,0 V! y1 x0 R0 [! @; w5 b/ m
globals
1 i: f# d8 Y/ F[$ H; U; z+ Y; j) T5 n
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
  c, J# X# x1 ~5 a) [6 }  grid-y-inc               ;; the amount of patches in between two roads in the y direction
2 p. y; N8 i! b2 ]+ c5 F$ {3 w  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
0 y: H0 l( ^# e: n7 k" k$ j, `" N                           ;; it is to accelerate or decelerate
3 N- F8 n* q$ L+ j& S  z* f  phase                    ;; keeps track of the phase; E1 k5 U4 ]# N
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure8 t& q) I# C' t& l1 b/ p  r% t
  current-light            ;; the currently selected light  A6 ]- z/ Z5 I/ ?2 Z
$ r  [& G$ |' N2 \
  ;; patch agentsets& ?0 H5 m$ a# M/ b' X, O1 e
  intersections ;; agentset containing the patches that are intersections
* b# m/ I( \# y, y" x  roads         ;; agentset containing the patches that are roads1 U; L/ L; ~$ Z! ~: ?. y2 b: s, B0 q
]1 _3 o) j) c3 i& ~- @

- L' h" a: m8 i4 Qturtles-own
4 l; ]# e" x+ E0 ?# K( I( Q[
" b$ ?# i: C: w" L  speed     ;; the speed of the turtle/ G6 o+ L7 G8 }! g
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
+ A: c" G  y6 F: T  wait-time ;; the amount of time since the last time a turtle has moved/ l" x8 j5 f) ~0 V
]
0 M2 V+ I. z; Q9 k" ]# r
' U1 M$ G- c7 Y! T6 Rpatches-own4 i0 X- W+ c$ X: L* h8 C
[
9 R( O% r" @6 K- V( \  intersection?   ;; true if the patch is at the intersection of two roads
( \& K$ s" [% {, c( B  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
9 P) K/ f1 I; |3 R                  ;; false for a non-intersection patches.* C  k- ]- T; {' N( n1 S
  my-row          ;; the row of the intersection counting from the upper left corner of the) a4 o. X' a4 k! q) |0 e/ u7 y+ H' p
                  ;; world.  -1 for non-intersection patches.
# B2 C- ]+ J7 y  my-column       ;; the column of the intersection counting from the upper left corner of the9 L' k  n" m8 P$ J& Z* }
                  ;; world.  -1 for non-intersection patches.
/ ]) L- f. Y  R! A& }  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
! j% V$ f  d9 S: w6 q- Y  auto?           ;; whether or not this intersection will switch automatically.
* R) J6 a8 D, i                  ;; false for non-intersection patches.- L: T4 N  k, c  H" ^
]7 S. _7 Y9 r$ s8 N: u1 l
) Z1 e+ P  w8 a1 g* s$ D

1 \! ?7 ^6 y* ?% z7 B* p4 u; z& h+ a;;;;;;;;;;;;;;;;;;;;;;
9 Y' K* w) f7 L# H% X0 H. _& j;; Setup Procedures ;;) n0 ]6 `. F& o- q
;;;;;;;;;;;;;;;;;;;;;;. \0 ]( G! B6 o6 Q' o: V
/ p8 K$ @- |  O0 D3 O
;; Initialize the display by giving the global and patch variables initial values.- G- l$ P6 k& Q$ W7 F
;; Create num-cars of turtles if there are enough road patches for one turtle to
. Q' \- n  ~( e;; be created per road patch. Set up the plots.: p: A) w2 j) L% v/ N
to setup
- m5 ~1 h4 J3 F% Q$ g9 n  ca1 Q4 l5 g: t! x% S. a
  setup-globals' j0 u# E4 b9 ~3 L9 R/ b3 ~. e

' K! h9 s& }, n! [  ;; First we ask the patches to draw themselves and set up a few variables/ F+ \/ D7 l2 F8 p' C
  setup-patches% p  P7 E- L- H% g# |
  make-current one-of intersections
' s" c4 D' c1 H/ s6 z  label-current
- ]# p& C2 A3 I, H  {7 c4 k% n; i
8 L- W* a4 {- C  set-default-shape turtles "car"2 v0 x& y& m' h, H4 {, ~& I
3 ?: ?1 R$ X7 z' r& Z, h
  if (num-cars > count roads)
( X5 v4 T. o6 U/ P7 Z0 j  [8 a1 e# T3 }7 h; ^2 a$ H) H0 \
    user-message (word "There are too many cars for the amount of "
+ D! U: a' L! F' r2 {' R                       "road.  Either increase the amount of roads ") O* i0 K6 w4 i1 ~0 N
                       "by increasing the GRID-SIZE-X or "
* T2 s" R' Y9 E& s, [! x' }                       "GRID-SIZE-Y sliders, or decrease the "- g4 N  B, C& L8 n; j9 J
                       "number of cars by lowering the NUMBER slider.\n"
0 |! ]( q" f+ {& g) K, \+ }                       "The setup has stopped.")2 \* q; A# C# n% {0 J9 y
    stop; p' @& O6 y- V! B. ?, \) h
  ]
& c* @) p1 @, n2 I9 D% o( U9 ]$ @* O$ Z
! ?  y, n2 L( o4 C9 O! E* a  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
1 r# C: v1 s1 D3 N* F1 F$ q  crt num-cars; Z5 a$ R# z% P+ \- Z
  [- i" M1 H2 i7 G$ F* X: Y2 `
    setup-cars
0 z  D% S$ B+ p0 l# U9 k& _  W    set-car-color) U+ C  ?4 u. y
    record-data
5 T$ j* o9 x+ K" \4 Y1 R' G2 {5 {  ]0 f. p# \8 d/ I2 d
2 x& ^% `3 R3 ]' ]
  ;; give the turtles an initial speed; z. G; z2 H" K9 x# P. [- F
  ask turtles [ set-car-speed ]
5 O  p6 ?5 D: P. [$ |9 g% u0 j; c1 Y# W; X' A
  reset-ticks* ]2 I! G  I  |7 W4 Q0 ]. c
end
1 D9 G4 V1 A" o: I9 P4 B6 N: U4 X, W: i
;; Initialize the global variables to appropriate values& N. s0 C: d5 a3 a+ V0 C1 s" U
to setup-globals
. a- l, V) B  ~; N; u. `  set current-light nobody ;; just for now, since there are no lights yet
) ^7 P3 Z) ~+ R: L  set phase 0) W1 I$ I% {" D, j. A
  set num-cars-stopped 0- B9 L2 B9 k/ r, a( L8 X
  set grid-x-inc world-width / grid-size-x
2 C3 Q2 M2 j- G  set grid-y-inc world-height / grid-size-y
% v) s" o$ e' A- T; U* i; j" h1 h. S! ^7 a2 e( `  R. S* |
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary& y& T- V+ B+ {0 z" a- \* n
  set acceleration 0.099( p; ?# W4 p: A% ^$ i5 n
end. v" E0 O+ k' x+ X0 k$ T
! [# P" ]( y& ?1 |9 k, g( Q
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
2 T9 M. W! G" a8 |9 O. ^# M$ x) B;; and initialize the traffic lights to one setting
8 ?, h/ P+ t) e7 hto setup-patches
) |8 f! |) w5 h6 ^& `/ |  ;; initialize the patch-owned variables and color the patches to a base-color
$ [+ g% |) B$ B  ?% Y% j/ S  ask patches
& l  \( m+ \" G/ k% u" [! Q: p  [- |" @6 G) T4 N; j- n+ f/ m7 T
    set intersection? false& F4 a, @; H( `( y1 l
    set auto? false, }# t) W: F5 U
    set green-light-up? true
9 k( U' w; \- ]/ ], c$ a    set my-row -1
: ^; b5 ]6 Y% V! \6 M    set my-column -1' `2 n1 @5 _+ i- s
    set my-phase -1
1 O$ U- l* s7 t: L- l    set pcolor brown + 3# u1 z! O2 Y$ E& o. t( i. L6 [
  ]( S6 z; V# Z# q. O' P! N' q$ M

, `' [. u- K5 F9 n  ;; initialize the global variables that hold patch agentsets
- z. z+ j. Y0 B( D! [+ ]6 l  set roads patches with1 R3 M- i( E% k! }7 m& ^
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 Y/ s0 W3 L) S# ?0 f5 P, A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 A- m6 c9 L7 O8 B" A  set intersections roads with
* z2 F! G% R- S7 R$ Y4 U- c) {    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
' G& N7 P( y& `' M! O3 u6 T/ x! n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( o8 J6 L2 B/ E: U: p2 \

3 P1 F. _2 B/ a  ask roads [ set pcolor white ]
' s7 Q9 D* y1 u8 L    setup-intersections+ S' ]% l  Q3 a/ W+ |( g7 q3 t) I
end2 }0 O* G9 H+ {
其中定义道路的句子,如下所示,是什么意思啊?0 u9 N+ L% F  s" I3 W" F0 c" `6 W7 M7 l
set roads patches with
- v- g3 w1 |1 N    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ Q$ ?, \) A# @    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 v3 T9 Z: K9 {. i3 b& 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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