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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。
' s; N& e3 G" r" d' O  Anetlogo自带的social science--traffic grid这一例子当中,6 g, ^3 I" ?% A: f
globals- _! P. c/ s* P4 p1 I
[6 _; r0 L& Y: k/ b
  grid-x-inc               ;; the amount of patches in between two roads in the x direction/ `  x( y1 R7 Z/ q. n) F/ Y
  grid-y-inc               ;; the amount of patches in between two roads in the y direction' S0 U& j+ B  r8 |  `# c
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if0 b; m5 K3 W' \$ r6 s1 U8 ~) ~1 u) a
                           ;; it is to accelerate or decelerate
5 e5 j; `: h% @+ D- k, W  phase                    ;; keeps track of the phase5 [7 c; x5 O6 E, f8 }/ d* r9 q
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
# Q9 Q7 K8 m9 T& `5 E  current-light            ;; the currently selected light
' _" T. A- ?1 {: x
" ^* X  L3 g; C  N5 }  ;; patch agentsets* n2 r) k: l5 e5 z/ C
  intersections ;; agentset containing the patches that are intersections% Y" G# x  C) v1 T
  roads         ;; agentset containing the patches that are roads
/ j; _0 y9 Q% p3 w- m]% n* H& [# H9 k4 Y  \
  f/ |( ?" X9 t# Y$ _' t
turtles-own
6 u8 X* _& x7 U3 g) n[
; X# q' ~! x7 W, D  speed     ;; the speed of the turtle6 E! N0 ]- u. B0 }2 O6 S
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
; l5 B; }: E& n, q4 E  wait-time ;; the amount of time since the last time a turtle has moved
/ E4 g' E" m  e  J/ g3 g' H0 u]
* r4 ^: j( l  l, I. }/ h6 d- `5 X& V) O4 x7 X
patches-own
( Y( T: x. l2 ?& @[
& U& t0 `. S3 f9 ^! U% Q  intersection?   ;; true if the patch is at the intersection of two roads) M2 j$ R1 ?& D
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
9 \' y- V* v, @7 z) C                  ;; false for a non-intersection patches.
3 K7 Y, o" L5 o- A  D  my-row          ;; the row of the intersection counting from the upper left corner of the
1 A' h7 |9 B" d3 q4 J# U- }! G                  ;; world.  -1 for non-intersection patches.% r; _6 S3 E. t# o
  my-column       ;; the column of the intersection counting from the upper left corner of the
1 t) s0 t/ z% G' e8 i) U                  ;; world.  -1 for non-intersection patches.' }) v4 f, V3 ?; x
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.; n  Z6 P0 J9 j  _! F0 v) ?  V
  auto?           ;; whether or not this intersection will switch automatically.8 S( w, Z, Y1 z0 G  z
                  ;; false for non-intersection patches., q7 Q  H( `" j
]3 J5 Q8 z$ R: E4 ^9 B# O1 T  Q
) }! D' M6 m( |0 h
+ v  b& u$ t: j  w
;;;;;;;;;;;;;;;;;;;;;;
4 a; U6 D! @6 d% A;; Setup Procedures ;;
2 i* w: W# ]' K- N! {! E' @;;;;;;;;;;;;;;;;;;;;;;. X" @) m+ t; |2 }  n- ~* `2 x% b

7 [2 {" l2 g/ \6 o;; Initialize the display by giving the global and patch variables initial values.+ q/ @6 a6 d5 L9 B2 ]  F+ X' G
;; Create num-cars of turtles if there are enough road patches for one turtle to! c- x& D( o$ W8 J$ O0 c; t
;; be created per road patch. Set up the plots." c! ?4 Y, a6 ]% O# k5 {6 u$ Z
to setup
% I3 l: @  Q1 q* L( n8 ?/ q  ca
6 E2 H. P! |  X' w! F1 H, q$ Z  setup-globals; ?- E+ H5 L# u! G9 u' W* m8 T- ?

, M! {6 o) {( U' n9 T8 w  ;; First we ask the patches to draw themselves and set up a few variables
' g0 ~2 N9 C4 e  setup-patches6 }" H- ~) s; g/ P2 ?- A" D; x
  make-current one-of intersections
% K7 r+ o! l+ f: r4 z  label-current- r3 T( f9 {8 d7 W: `7 N
5 O; i3 S, L  q% G: g
  set-default-shape turtles "car"
) U6 _" S5 z* p5 Q4 ~% u& C$ y2 l$ x8 H5 \6 F( M! J" ?
  if (num-cars > count roads)
1 m. f4 w& B/ p- g  [
$ `$ t$ k# Q7 V0 j% x# V    user-message (word "There are too many cars for the amount of "
' \! O, q, u+ v# G# w                       "road.  Either increase the amount of roads "3 B5 V% m: f: q' |
                       "by increasing the GRID-SIZE-X or "
  n7 o( d: O- p$ G                       "GRID-SIZE-Y sliders, or decrease the "
! `; u3 G0 K3 @: M6 Q: ^0 h                       "number of cars by lowering the NUMBER slider.\n"
$ t- f: Z! n4 ?7 I: p2 |                       "The setup has stopped.")  n& e4 @% `8 u
    stop
5 D% i7 h9 ~  n* r: r4 M  ]
8 G) f+ L1 w7 x  J2 O* Z8 w7 `5 I' h  O. V4 P, t
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
  a9 y0 M6 B6 q+ v7 v: J' A  crt num-cars$ e9 r2 ]$ \5 B4 h# B
  [
" [  M3 o4 T2 S) O1 ~$ x$ u    setup-cars
: E2 t% q& M1 |6 I/ u    set-car-color
* \; ^$ a( m1 v/ X9 S, C) I    record-data- e, [  Z* w% z
  ]
: q8 O& t% E( Q; y8 a! P
6 P: |2 c$ q3 S0 ?# G  ;; give the turtles an initial speed* T" ]! N2 F6 p7 o# ?
  ask turtles [ set-car-speed ]0 z$ C& ~: I$ V" R

# @2 m5 V8 a4 c; n" O( K' s  reset-ticks
* b+ @6 D: C: {& H6 q6 ?# Gend8 r8 X7 ^0 U; T$ ]5 a2 H5 _
- A. {8 a3 `# ~$ V! @* H# x
;; Initialize the global variables to appropriate values
0 X7 H% }/ {( m7 q, qto setup-globals
  x# w, J6 b" ]( c* A. f  set current-light nobody ;; just for now, since there are no lights yet
+ s& Q" U* v7 A# O  set phase 08 v( h0 a: A/ u3 ~
  set num-cars-stopped 05 |' y! K" ^+ o0 |$ m# @. ^
  set grid-x-inc world-width / grid-size-x/ S: I2 d  |  z* d7 |5 q' ?  K
  set grid-y-inc world-height / grid-size-y
% c" f  @6 |, V3 u, H
/ o9 e# F; m" ?4 Z/ |  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
9 ]8 b4 F5 M( i! N4 y  set acceleration 0.099# q; h- J! h6 }- G, T0 c, v
end+ j" k9 Y1 G+ f4 ~) l

  D- `, [; o- v! R" o;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
6 I3 J; h& E* M9 S;; and initialize the traffic lights to one setting0 D6 i2 j0 Y8 ?7 Y7 i
to setup-patches
9 _7 c, k8 J! L  ;; initialize the patch-owned variables and color the patches to a base-color# C0 k. v# j9 g+ r* J
  ask patches
! G) W! P. m  B( C8 s  l  H  [% U; G  v3 @8 l" X
    set intersection? false  K2 `$ V. o' _* ^1 v2 m6 T
    set auto? false
, e( Z3 S/ r. {' y    set green-light-up? true1 _4 n7 v  l5 B9 ?& D
    set my-row -1! c9 [: c# k* j6 H. {5 n
    set my-column -1- {; z$ V1 j: ?1 o7 ~
    set my-phase -1& R4 Z# F% g3 Q- C
    set pcolor brown + 3
( Q4 K" i' H; F& t+ [/ x  ]2 E  @0 Q7 o2 L. j, @) x6 W
& E( R! F! \! S
  ;; initialize the global variables that hold patch agentsets
0 E3 n  u! i4 f2 _: J& C  set roads patches with  \8 f- }8 `3 [: t  V' Z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( ^0 |  M+ x& @) K) o
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ _3 D8 p& G( `  set intersections roads with
2 Z- {; E9 @7 e3 @; s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
* C6 y! ^5 K# n3 E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 V1 N  d" h" o5 ^# u; v4 y4 G" ?  e! P" N) u# w
  ask roads [ set pcolor white ]
9 y8 m6 E. _0 W0 Y( U1 n    setup-intersections6 D# p8 C( i% z6 u. V2 [; z0 s* L7 ?
end
5 z& d8 s9 q$ K$ L1 a% x8 S' Y& p其中定义道路的句子,如下所示,是什么意思啊?
3 F7 F0 j( w5 _5 i7 w set roads patches with
+ W$ Q. q9 `; _8 ^0 y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! w9 B! y  e3 c& h% \+ k# V) d
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' i4 X) T" o: N+ F% Q. n9 J# |' E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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