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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。) w* f# F& F/ F1 l! Q, e+ U* A
netlogo自带的social science--traffic grid这一例子当中,9 A+ ^. L$ L1 ^) I
globals6 P; B& y" H- H- f8 m" J1 N
[. J! U: V* M6 ~  r+ A) W
  grid-x-inc               ;; the amount of patches in between two roads in the x direction$ B: w. N! D) h" T8 Q  D
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
: q& g, N4 W& a/ r+ R! ]' A  acceleration             ;; the constant that controls how much a car speeds up or slows down by if# u7 b0 A5 ?- D( d
                           ;; it is to accelerate or decelerate7 B3 t* k" {9 z1 v3 G0 v3 n
  phase                    ;; keeps track of the phase
& H4 L% ^2 |  ]: M# _) s  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
9 b' \% J& s- ^$ ^" P/ Y  current-light            ;; the currently selected light
0 }  n* S2 o+ s  P& u4 Y; r+ p2 I8 w: H: y) D
  ;; patch agentsets
+ `! V  e5 _2 H* W  intersections ;; agentset containing the patches that are intersections
$ W1 I* _, y' |& g+ F* _; Q" X7 s  roads         ;; agentset containing the patches that are roads3 w( C) w/ {1 S8 X+ j
]
2 m* k- ], z7 q. y  s
+ H! y3 A2 b* Nturtles-own
- ?; ?' m9 Y7 u[
+ {$ J; H6 N5 M0 u  speed     ;; the speed of the turtle) ~3 }+ x8 H$ R) \% ^! N5 |+ V
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
1 U% b$ O* I7 G' g+ c  wait-time ;; the amount of time since the last time a turtle has moved
6 [& ]4 H4 ?9 ]6 }- }]
, P7 I. x! X" z9 z4 O
% l6 A5 c5 V" j$ Epatches-own
. H1 L3 }$ _7 U3 Y) K[
1 K0 r0 N5 B) Q) B  intersection?   ;; true if the patch is at the intersection of two roads; ~) B$ P- H8 q+ @- d
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% W  w3 q0 _  u$ U. F0 g3 _, R                  ;; false for a non-intersection patches.4 [9 e( k7 ^" |0 C: J2 G
  my-row          ;; the row of the intersection counting from the upper left corner of the2 i) ~( P) C0 z0 g2 x! }; R
                  ;; world.  -1 for non-intersection patches.
1 W: \! Y' A8 I; K! W' l4 E5 Y( {/ y  my-column       ;; the column of the intersection counting from the upper left corner of the
6 p( `) j5 I- i5 K9 ]                  ;; world.  -1 for non-intersection patches.
& V# M- @( u9 o! B3 b  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
% V, x. j4 n7 D, w8 V* P) H  auto?           ;; whether or not this intersection will switch automatically.
, V, Y# Q2 `$ ^                  ;; false for non-intersection patches.
# |8 }2 w# o0 \: Q8 l' ?( E, z]2 S+ o8 `4 \: r8 n  ^

, l) @" L5 p/ E. C
( o' v% i/ L9 z;;;;;;;;;;;;;;;;;;;;;;
1 O7 t9 }& Z2 ^  F;; Setup Procedures ;;
. B! {- M: G( t;;;;;;;;;;;;;;;;;;;;;;  f8 g5 Y; w5 J  Q2 `- P6 k
3 J: t7 S: \# I* E$ A7 k- n0 M
;; Initialize the display by giving the global and patch variables initial values.
. e+ H0 E- J: l" r;; Create num-cars of turtles if there are enough road patches for one turtle to
" N8 M. f* n+ B+ f3 M8 X1 e;; be created per road patch. Set up the plots.
3 y4 Z9 F- v" X, fto setup: l1 h% [" Y/ h: w! a
  ca
7 N: ~* r8 B. y. t* p& ~  setup-globals$ p3 j/ W+ b9 ~8 n& e
6 p; z8 u& e+ s8 A# k, l
  ;; First we ask the patches to draw themselves and set up a few variables
; ~3 Q7 F- [; o4 `  setup-patches3 K* \4 L8 a( L$ [' J6 l. D$ h; J$ i
  make-current one-of intersections
9 M! \, o& V8 H  label-current, g- {# c4 h' f/ i" g* z6 N
% n3 d0 T8 ]+ W  l7 |: l
  set-default-shape turtles "car"  h" m. D0 ?1 k$ d
+ \' C' E. b# J# f1 b2 Q! l
  if (num-cars > count roads)) S7 _. {- L3 c- X
  [2 u# C) x  ]/ i
    user-message (word "There are too many cars for the amount of "
* z# F+ u% r2 g3 h% T- e7 v                       "road.  Either increase the amount of roads "
. w  Z0 k! N0 }                       "by increasing the GRID-SIZE-X or "$ J( j9 w) `( s7 ^
                       "GRID-SIZE-Y sliders, or decrease the "
- Q4 N2 ^- m' T4 x7 o8 t                       "number of cars by lowering the NUMBER slider.\n"" Q( J! C+ L4 C; p
                       "The setup has stopped.")
: J, U+ C6 t) h9 G) X    stop
) Q5 Z; [  f+ P( O  ]
# V: B: u' f( |5 J, P5 Y  n( ?
, Z" P0 O; h  M" n: n' \  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color- d2 g7 t- z; g% b# X4 L$ T- r  G2 N
  crt num-cars
( x# e6 J1 v* c) N" E0 w5 q  [6 U, Z  R' ?( ~: ^' Z  s
    setup-cars; P/ h5 o, w  x( A: S% t/ _8 }
    set-car-color. d! Z; F9 M$ o0 ?
    record-data
$ P7 x0 z9 ~+ d) O: L  ]
% `% y1 V* B" K* ^: a  Q5 y5 }
7 U& E* n, w! m: n: N4 @  ;; give the turtles an initial speed5 {4 O2 H4 a* M( B- y; [  Y
  ask turtles [ set-car-speed ]
, ]+ H0 g" C: L8 x% f7 Q2 Y6 U
: j+ ?- [! j3 H  D& P0 b* {  reset-ticks
2 u/ S1 e/ t, Q2 @8 V) _4 Kend
6 q! ^1 z& \: s" k
8 s' _: ]/ ?4 A$ e  `! L, t;; Initialize the global variables to appropriate values* k% S; @' d0 K5 Q. E1 g1 s5 Z
to setup-globals
7 y: J0 ]! q+ F0 _: ?( o  set current-light nobody ;; just for now, since there are no lights yet
  ^3 O( m1 q) O: v5 Y* Q  set phase 0
( V1 s) J% ]0 d7 _  set num-cars-stopped 0# i' m3 N, b3 Y$ m) [# a
  set grid-x-inc world-width / grid-size-x3 S7 _1 N* l( ^4 W9 B! \% u
  set grid-y-inc world-height / grid-size-y- t$ Y' Z- r, q" v
6 A& Y) f. p9 J6 F+ P
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
6 U% R$ u" L" C% w6 w  set acceleration 0.0997 o; Q" h' S; \& y
end0 @4 c0 J, o' v6 z
& R& _; ?% y0 E+ c  n8 x
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
; F3 b( i$ w: }: e! C9 o$ x;; and initialize the traffic lights to one setting
" C7 c' s+ J. q. \$ uto setup-patches
1 w5 w1 m& ?0 Z# n  ;; initialize the patch-owned variables and color the patches to a base-color- D8 A7 Z; c* u
  ask patches
* R% O  a2 n& y4 t+ ~! ^+ [  [
' z- W+ Y" G! C9 X/ d0 p/ o# H/ ^! y9 e    set intersection? false; \% B% i1 J) N9 ^
    set auto? false
6 k8 y3 n  n7 M5 l% U, h, P: @    set green-light-up? true' Z( H4 B2 ?, e. }6 ~+ k( O
    set my-row -1
' l. f8 b; H* W  H    set my-column -12 j* n+ Z: G( Z( q6 |4 @6 |
    set my-phase -1; K2 @# G* {% X7 h* h* M; i& p1 O
    set pcolor brown + 31 J; n" D) E' I" H7 d
  ]
) W# _% z% \6 e. p2 h! V+ E
3 V! J( W3 D- S  ;; initialize the global variables that hold patch agentsets( ~; Y2 Q  Y9 v1 L6 ?
  set roads patches with' D0 l" J9 j( r. v0 I7 O
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
' {) {4 p  v, `3 b    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 @3 @6 E; G  H: H# J$ w! H! e
  set intersections roads with
6 o* z: V- j* G* T* W6 |    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and& ^) B; W6 \2 S0 Z& F# J0 ]
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: O0 W" }6 v- |( Q! i
& X% Z8 I9 F3 r9 s" O  ask roads [ set pcolor white ]9 h! W! @1 t. I5 `; E/ {$ v
    setup-intersections
* `# u8 c, d8 ?" W5 w$ hend9 [) C  [/ r2 h  C' P; j4 A6 Q
其中定义道路的句子,如下所示,是什么意思啊?
/ u( _1 b. t& b set roads patches with% v2 q" g9 C/ y3 Q; F! z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& x7 p6 E% w) O3 S5 H    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 D2 B8 }3 p3 G& w9 V$ J
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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