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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。
6 p+ w7 d! G, h4 nnetlogo自带的social science--traffic grid这一例子当中,% s3 P1 Q, }' U8 R) B
globals4 N; R% k/ K5 R
[
& N: L1 E0 {2 e  g* a. W  grid-x-inc               ;; the amount of patches in between two roads in the x direction
) K/ o8 t1 x, w# i  grid-y-inc               ;; the amount of patches in between two roads in the y direction4 `% g% e9 F# \" j- `
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
, c* j4 f+ P" _  v0 k                           ;; it is to accelerate or decelerate5 [, X: `3 G# ]) N) ~- P
  phase                    ;; keeps track of the phase. m, [) G. O% D& R: Q; |( }5 _
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure7 k; D+ M0 W; A" [$ r! E  b
  current-light            ;; the currently selected light
1 J5 ^9 N& D( P" a
6 X. J7 E0 ~. x9 n/ B, B  ;; patch agentsets7 S: u5 U% Q# k+ ?9 Z: t
  intersections ;; agentset containing the patches that are intersections/ f+ H6 ]; F& z/ R2 @6 r
  roads         ;; agentset containing the patches that are roads
5 Q- L4 S3 q* K+ H]
" S5 W0 H% g& e, U# [. \6 `& G# K5 C0 ~- M6 y9 G9 C* _
turtles-own
' g6 u/ I+ x) x: Z. b+ \[
5 a1 L! @0 l* W" x- p6 N& @  speed     ;; the speed of the turtle
9 j( m) `0 a8 `6 z1 [% ~  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
4 j: n# n3 m" X& S  wait-time ;; the amount of time since the last time a turtle has moved
( A, y! r0 }" Z) R& C  m+ D]0 q  k* @$ P2 f6 K7 I

8 b9 N8 ]7 B. b2 npatches-own
3 v8 D1 l$ g. i* e[7 z- M: g: W% n) z) U& R. j# x
  intersection?   ;; true if the patch is at the intersection of two roads% M" U9 A& E4 z# S# {4 Z: k9 I
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.5 S7 n6 b( q6 N
                  ;; false for a non-intersection patches.4 {3 d$ M% N/ @
  my-row          ;; the row of the intersection counting from the upper left corner of the
/ D# T. g  z+ b3 ^+ A5 b                  ;; world.  -1 for non-intersection patches.
1 c2 c+ `( m( J1 i, [" V  my-column       ;; the column of the intersection counting from the upper left corner of the
, }2 |6 t! @' V3 R- n( p5 W) L                  ;; world.  -1 for non-intersection patches.. C9 X+ Q# ~3 Y" k6 [7 S
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.- ]! X# |6 n  U' M% V
  auto?           ;; whether or not this intersection will switch automatically.
7 h5 M+ R7 {. f7 S; d" h                  ;; false for non-intersection patches.
; d6 J! `( k6 Z2 t" d]
" h8 |5 V0 e' E$ C
2 N2 g, N1 y# b$ ^: C
. J& \$ w1 h# c! `;;;;;;;;;;;;;;;;;;;;;;0 I/ L6 \% ^7 M: D6 h
;; Setup Procedures ;;
# |. A+ W& m) W' e( {- ^;;;;;;;;;;;;;;;;;;;;;;3 S* o9 t" s" s. g# I; x0 r

1 M; g  d1 c8 o$ q$ H6 Z. Y, G;; Initialize the display by giving the global and patch variables initial values.  w  A' D8 M5 q7 c9 p! L
;; Create num-cars of turtles if there are enough road patches for one turtle to# T# |1 W5 }0 [( y) f2 d. v- y
;; be created per road patch. Set up the plots.0 \3 T( r1 q; y' D
to setup; y. P/ P2 F$ v8 H' u- I
  ca% O# t( H) g9 q8 \7 i
  setup-globals
5 @" E, |& ~# ?! ]: ~
! B: i0 c6 n0 h. C  ;; First we ask the patches to draw themselves and set up a few variables  D* ^. j7 c5 X- z2 M$ h
  setup-patches9 `. L( K2 F% r2 \# U, R$ ]& S
  make-current one-of intersections
( @+ z5 N" ]* k; y  B  label-current
- d8 G  z  y' [  m$ X! A
7 k, O# c9 D$ |8 p1 P1 S8 o  set-default-shape turtles "car"4 M9 ~0 A" V- P

% q* u3 Y" H9 V* E/ \$ \$ b; O  if (num-cars > count roads)
, @& e. }& R9 F, p+ g; H1 y+ }  [
! |" f, F, w7 `  [# U& y% y    user-message (word "There are too many cars for the amount of "2 c2 g" \# e$ m' `8 `
                       "road.  Either increase the amount of roads "
& m% {! U" _' i" V+ C1 S& R                       "by increasing the GRID-SIZE-X or ") W6 N9 n9 M, P9 v  u  i
                       "GRID-SIZE-Y sliders, or decrease the "
: v, j: T' L; v, o% {* l4 I" d) Z                       "number of cars by lowering the NUMBER slider.\n"
- L: e3 N+ ^; y: g1 T                       "The setup has stopped.")
. }0 p7 _+ E9 S    stop% ]# L$ G7 i3 e: R. Z# y
  ]  {# j% u! J) m' D* a

' W. Y4 S; L0 M) l0 _8 ?7 y- G/ p% d  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color) [) L/ @, w; \: L: W1 n
  crt num-cars
% F1 @) Q5 K! t( H' J. M  [
# B8 v) g) C2 }7 c& j    setup-cars
, }9 c# Q3 a0 j/ w$ F    set-car-color
+ I, _3 B0 ]8 X1 W& G' k4 I    record-data
' C8 ?8 h* Z6 R- e4 F) s' `! I0 e  ]' s' v# @: a7 l
  T% J3 m( Z7 u" m* Z
  ;; give the turtles an initial speed$ I2 G7 S1 F1 ^. a! f& K/ H
  ask turtles [ set-car-speed ]3 V) `. n7 G. ^3 v
& W1 i0 \% [) v/ o9 ?
  reset-ticks# ^; m; L2 L0 M" P& R
end. x1 N: B8 r! u( D$ i
. J* N4 W- s1 P# I0 k
;; Initialize the global variables to appropriate values
6 t7 x: K2 y0 s8 V+ b& m/ ^; ato setup-globals
: l1 k5 ?  @9 Y7 x& G  set current-light nobody ;; just for now, since there are no lights yet# n1 V& T  p8 |
  set phase 04 j  ~6 T/ ?7 q: w
  set num-cars-stopped 0
6 b* U+ N" Y; {  set grid-x-inc world-width / grid-size-x
3 c5 N6 m1 F. f1 q$ F5 J7 ]- X5 z  set grid-y-inc world-height / grid-size-y
, n6 E& p6 }/ F" C) ?, E# S& q
( J4 f" l% @8 E, x) ]  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
6 M& j: O/ F2 Q  set acceleration 0.099
+ p# S# L4 `1 O, ?, u, r% H( ~# S& {end
) e& g, U' C! d
: T/ e; T9 V2 b+ B! r;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
( [1 Z, ~6 E) `9 d2 f;; and initialize the traffic lights to one setting
# J5 h4 }6 v1 C7 ~+ O9 Y  Xto setup-patches' R/ P; c( S2 w  p0 J3 G
  ;; initialize the patch-owned variables and color the patches to a base-color8 D7 ^: V8 z, J
  ask patches
( _3 g  |& w8 Q% W! m/ t  [
( M" i  b9 ]6 F: V$ q9 n    set intersection? false
0 c+ S: }9 g% G' u4 N2 h    set auto? false  [. [; \2 ?4 I: w, d
    set green-light-up? true# e5 S, u) X* @/ C: i) O
    set my-row -1+ e7 c4 n  Q, Y3 R* P
    set my-column -16 c' ?; I& b) U- W7 e+ R
    set my-phase -1! l8 ]0 V+ ^6 d* b' {. d( o
    set pcolor brown + 3
% H; B9 L( u$ |  ]
9 x' r7 [& h* b$ z3 Q4 Q" H$ \/ ~8 {( T" F, Z0 Y2 v
  ;; initialize the global variables that hold patch agentsets
7 I% q; v0 e; R" }  set roads patches with: i, l; s- v2 Z' x, \' ]
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ g! }* W4 c* X$ j; N    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  N% N1 b2 A" x; t( m
  set intersections roads with# a8 @* _2 f9 s$ V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and" `& c9 y, s8 c$ J) L+ v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 m# F$ ?5 B  N3 w5 Q7 \1 ]
( b9 e2 l1 d) a
  ask roads [ set pcolor white ]
6 y" l+ L5 ^- X1 ]! z    setup-intersections  a5 x5 ]/ {! a
end3 l& W! G) O) n& ~
其中定义道路的句子,如下所示,是什么意思啊?7 G& b" T# j  X1 n$ G7 q1 @
set roads patches with
3 n7 {- d* Z2 f8 Y* @) s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 p) b* b( [0 D, d9 g8 a    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& y( @  J4 D$ ~1 C% f
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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