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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。! g7 Y+ i: N/ {7 Y/ T! J+ [! t) }
netlogo自带的social science--traffic grid这一例子当中,, J: e8 i! W- |
globals
) Y; @" X' }& c) T5 T* I+ f[
7 n& I+ `0 t5 h0 U0 Y! t  grid-x-inc               ;; the amount of patches in between two roads in the x direction! e: ?3 l/ Q* m9 ?) V
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
! v# ]9 g. E- e* i; X8 c" [  acceleration             ;; the constant that controls how much a car speeds up or slows down by if) ~* F0 b8 q+ [* J3 @+ f. X& D
                           ;; it is to accelerate or decelerate2 Y- q7 ^" i: {4 \  P3 I" S! S
  phase                    ;; keeps track of the phase0 ^+ j6 m) x! h4 N, T- Z
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure( X* D+ Z8 N5 p7 A
  current-light            ;; the currently selected light4 u( a: @+ \" D

8 R3 S+ W9 F6 J4 Z: O# G  ;; patch agentsets8 [# P4 S! Q8 n+ |) F, f$ L! g; O
  intersections ;; agentset containing the patches that are intersections7 X, U& T& F8 z; t* W9 G) g- `* [3 ^
  roads         ;; agentset containing the patches that are roads! c6 j4 V$ m, }$ K( |( E
]
. y$ ?1 z0 S& d& H* N7 V; r8 e
: \3 ~7 }9 z/ j3 q: @+ z6 a# ^turtles-own
* {# p. }+ G: T: N[! G% r: C1 o% F: _( [
  speed     ;; the speed of the turtle# E: `" g' f* @8 w$ ]" V
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right8 o" H& S& n5 ?3 {7 Y8 e
  wait-time ;; the amount of time since the last time a turtle has moved
% _# f" ~* n) W" I. I1 X; G]9 T6 Q- |& I8 q; R2 o4 [- Z% Y# S8 E

$ m0 a+ [0 Z% ]" |6 Spatches-own% _7 g. c' [" G: @1 b" y
[
! `( p6 @1 f& d6 ~  Z) L  intersection?   ;; true if the patch is at the intersection of two roads& }0 h" J5 a. [1 M& B4 J4 y$ Q
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
1 h8 @( e+ D- s  ~# D- f                  ;; false for a non-intersection patches.
7 W: c) `1 z& q& u0 A; z. i  my-row          ;; the row of the intersection counting from the upper left corner of the
7 \5 [* d5 u# ]* C) @) m" m                  ;; world.  -1 for non-intersection patches.
4 k: r: w1 W8 u; M+ m  my-column       ;; the column of the intersection counting from the upper left corner of the
$ U; h- j4 f6 O0 `% F7 L                  ;; world.  -1 for non-intersection patches.
% A$ m0 w5 _5 l$ j  \* I  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.1 i1 a) L' S8 V* R
  auto?           ;; whether or not this intersection will switch automatically.
- |5 f# F4 I; O; T( `+ _* V/ D                  ;; false for non-intersection patches.
0 P9 W5 }: |7 q  X7 ]* W]1 w$ {! }9 F, Q
$ h% X3 y7 m$ s  u. l

* P7 {8 S' f5 i" v  l) z8 o9 t: A8 s8 g;;;;;;;;;;;;;;;;;;;;;;7 o& d9 M2 U: p( P7 g5 R
;; Setup Procedures ;;
$ W9 m4 E7 V2 [% B" J5 q% Z, X. c;;;;;;;;;;;;;;;;;;;;;;
3 X5 a$ Y( Q9 v& `5 {* F7 F' D' ]6 m! [7 A* f
;; Initialize the display by giving the global and patch variables initial values.1 B, p1 o5 N. N9 T0 a- ?
;; Create num-cars of turtles if there are enough road patches for one turtle to
5 Z0 G6 s! S5 s1 e3 q+ };; be created per road patch. Set up the plots.  l9 w1 r6 _/ k) a: `/ W% P2 n# ~
to setup2 B$ d8 }- W) a1 ?1 ^& E
  ca) q9 R6 R  U7 S7 I
  setup-globals
+ ?0 L9 v9 Z: o! \0 c3 b
5 O4 Z( ~5 G: y% z  ;; First we ask the patches to draw themselves and set up a few variables
$ o/ L/ u+ w+ o$ T# m  a: N0 {  `  setup-patches
% j* R. ]% ?3 ]3 @! v7 c1 e5 @  make-current one-of intersections
1 c  y! [0 K( F% @  C- @: H! u  label-current* U$ [' e! B& U# m; U" X% y
! O" ]' a1 _: C3 V* d2 C; r
  set-default-shape turtles "car"( ~3 E" d6 N; K2 d/ t2 @
+ ~! _5 ~& n/ P" B" _6 _
  if (num-cars > count roads)1 ~  F  m+ R1 c* h7 R
  [
0 `/ N: b3 y( c7 k  K: ?0 l) `    user-message (word "There are too many cars for the amount of "
) g% v  }: Q. u& f3 K                       "road.  Either increase the amount of roads "0 k" l( `6 Y& q, r$ K8 K5 s
                       "by increasing the GRID-SIZE-X or "
* W8 Q- _1 I7 S0 @- E- j$ ?4 M                       "GRID-SIZE-Y sliders, or decrease the "
) S  v0 {5 M, M' [0 ~3 m% r                       "number of cars by lowering the NUMBER slider.\n"/ U1 c) R- M4 P  N- P- S7 r0 W
                       "The setup has stopped.")5 S3 @* |: ]! n; T4 O7 z# x
    stop0 X6 D8 \! _% ?' {
  ]" u5 {1 R; n4 ^/ W' r( f6 H5 c

) s9 O! M# _1 U: O7 M* v+ G  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
+ @* E1 W3 e0 `# N$ }  crt num-cars
% G, j$ q: v7 U. K3 [, q" ^  [7 N1 Q( a' W/ t& `# B+ s5 @
    setup-cars6 F. a* d9 P% i: W& L- O
    set-car-color
. _+ D& ], U  _# w  m2 w5 U+ |    record-data
2 |4 a( s/ r* V8 q& N  ]
' ]3 {2 C; R: i7 V, I
+ A" L8 W% `5 H  ;; give the turtles an initial speed  V! P) Y7 B% T. ]' h1 S0 h
  ask turtles [ set-car-speed ]6 k! D/ T$ t9 G$ Z  d( z

3 k3 ^( S9 _- O( Z# a& V7 _. T1 k  reset-ticks2 `' T( q# r) p' [. o" @: ?
end) M0 R* }/ _* _

* o3 ]$ z+ ~- e* X- Y( k;; Initialize the global variables to appropriate values! x) v. R5 j' R1 e3 J
to setup-globals
: ^2 ?3 z) r& A& D* _( E  set current-light nobody ;; just for now, since there are no lights yet! u- a: S  K2 \3 a' V
  set phase 0
  [% Q& L# U& {3 p/ c' {9 E  set num-cars-stopped 0/ \; ?  o; ]1 \2 Z. b
  set grid-x-inc world-width / grid-size-x2 S) `4 k/ d7 a* d8 G9 c
  set grid-y-inc world-height / grid-size-y
( Y0 |# S3 n- v" F1 v. V( {
- G$ T5 }0 [( z0 X% h  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
, j4 C8 u% i$ d  M  ^; ]+ Q' d  set acceleration 0.099
  b  ]2 P0 x9 ], W& G" t- qend  v1 E4 O9 Q$ R# }: g
  R1 }  B+ f  J# Y
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,7 R/ M, B' E4 A/ T9 L# y7 A
;; and initialize the traffic lights to one setting
# |* P# G  V" n* L% S5 R0 ato setup-patches) P  _" r3 j4 L! h% p2 y
  ;; initialize the patch-owned variables and color the patches to a base-color" N- g- T% f  c
  ask patches
, v8 ?  r% F9 |) D2 c7 k  [$ G1 k% {* D7 K' y' N8 I
    set intersection? false
. h. Z/ ?+ }  J  v) k) E    set auto? false/ T3 }5 Q: a6 a4 M- n
    set green-light-up? true# ], r" [& c$ ]
    set my-row -1
2 ~+ P/ U! K, O    set my-column -10 K6 N& C0 R1 T5 T6 x; U  q' K& v
    set my-phase -16 y8 ]0 P5 p4 l" O
    set pcolor brown + 32 v4 r- }; ^, u9 `9 `8 I' t
  ]
' C# r, e8 S0 U  a3 P7 @
9 J% k1 {4 q1 n; E& Y- p  ;; initialize the global variables that hold patch agentsets% W$ Z+ y1 ^6 X1 j( H8 @
  set roads patches with
( \: J  o; o. Y/ D! B/ J1 C- U2 W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or7 V$ o* ^2 b3 c1 a
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! y6 c& n, z7 l1 f+ P: {. K8 t* [
  set intersections roads with
4 \% O1 T+ F5 |1 @    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
  ^7 K; y( }! G! ]; O1 }    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& g# z6 {) R: @, `% g+ I5 t
: L' `, w' t6 p2 A, f  ask roads [ set pcolor white ]: @  d! E7 ~& e+ y8 w2 ?
    setup-intersections; B  W* S- J+ N0 I/ N! e2 U$ g
end+ ^/ a1 y1 H5 T8 J  y' C3 B
其中定义道路的句子,如下所示,是什么意思啊?
; e3 |1 _7 H2 X- \6 ]6 V set roads patches with
( i2 E. C" I5 O  [; T. N" ^    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( p+ g) n! I) t" M. J    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. Q. _: t* V' z4 S) X1 ?( X5 q
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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