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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。" S5 S, E' t1 ?8 Z6 c
netlogo自带的social science--traffic grid这一例子当中,
% u: S0 F$ v5 O/ ^0 S, ?' p0 Vglobals$ [; }  d9 b8 [4 m% }" \# h& F
[+ N; w" U. ^4 i$ Z; S
  grid-x-inc               ;; the amount of patches in between two roads in the x direction: G& O0 w8 W( E( F/ w' o! e$ L% J9 I
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
' m" ?  n4 t7 \0 J! ]$ w% k- B; q  acceleration             ;; the constant that controls how much a car speeds up or slows down by if+ f! g. }3 @. R) V, P  s
                           ;; it is to accelerate or decelerate
. N6 q) K" t7 @  phase                    ;; keeps track of the phase
; s5 s9 X  n  D( _9 @! D  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure% \  K7 X' H* u# c1 L
  current-light            ;; the currently selected light
& j3 c" f4 r2 a5 n! v  X0 A7 g5 b5 f: j. M
  ;; patch agentsets
  ?2 ^% V8 m. N% l  intersections ;; agentset containing the patches that are intersections# q+ z4 m7 Z( O9 u
  roads         ;; agentset containing the patches that are roads0 m- W, B- z- I; z5 _+ T5 f
]% O4 ], z2 g% R# I

: h/ f% v) T3 p# ?% W- ]1 Jturtles-own
  O. b" k6 s2 g[
7 m! L: t5 x# m% J/ f" T0 Z  speed     ;; the speed of the turtle
3 p' Z( y, ]' f  up-car?   ;; true if the turtle moves downwards and false if it moves to the right8 ^6 n9 r/ k1 W! r# z
  wait-time ;; the amount of time since the last time a turtle has moved
1 G* y. n* R8 a& ^  k$ I2 A8 B]. L; k& F4 N2 o$ E$ b) n  O

$ ?& W9 T9 e: r" _patches-own9 v5 e$ j9 P! T3 C0 H
[
$ u$ k2 p8 o1 a! ?! r1 T# a  intersection?   ;; true if the patch is at the intersection of two roads" A% O( L$ u: w. P0 `
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.; j: `7 |5 J# b$ Q! F
                  ;; false for a non-intersection patches.9 w4 b, v3 |, h5 e$ h( h/ M4 A
  my-row          ;; the row of the intersection counting from the upper left corner of the
' u4 z% V7 h' t9 q                  ;; world.  -1 for non-intersection patches.
  P; ~( |: G, e! I, T  my-column       ;; the column of the intersection counting from the upper left corner of the
( Z8 K, ?8 E1 T/ \' M, H                  ;; world.  -1 for non-intersection patches.
* z( g& E' e" m& i4 s  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.7 U- D% [8 U. z4 u
  auto?           ;; whether or not this intersection will switch automatically.
$ o; |, l( Z2 Z                  ;; false for non-intersection patches.. B2 O2 s# t, A: f4 O" q0 q
]
; d2 M, H' Y$ P  H, V) E3 m1 |4 ~- j& J" f7 F+ F! B8 e
! B: ]7 z  b% n9 W  ~5 g
;;;;;;;;;;;;;;;;;;;;;;; `% X# V6 h$ X: o2 B3 }# R
;; Setup Procedures ;;, z0 f6 r  E! a
;;;;;;;;;;;;;;;;;;;;;;1 w5 I! S. S8 c4 M  u; J, {

' @7 n' k0 A5 G# {;; Initialize the display by giving the global and patch variables initial values.) ^% [( ?! g  X3 ~' K
;; Create num-cars of turtles if there are enough road patches for one turtle to
! P" M5 Y9 E3 L3 O& C;; be created per road patch. Set up the plots.8 O, X; y' L& i  m
to setup9 N# x5 S) x* z4 y0 ]* T( e
  ca
+ b4 N. m& q+ v# p8 t2 z1 M7 c  setup-globals! ^( [. F/ j% e4 \& ?& }9 l
$ R/ d" o/ F! g' x" ]; w# a9 c
  ;; First we ask the patches to draw themselves and set up a few variables4 |2 Y( Z9 M) l$ {7 f
  setup-patches
( u2 ?. n# N* w0 S! y1 Q6 l  make-current one-of intersections( e# {  |" g% u5 t- V. b; C( U3 P
  label-current
% R4 C% Z* V: z$ W* y8 ^% O/ w' V: d; N% m, U2 b8 w
  set-default-shape turtles "car"9 H7 I9 }% _1 T4 p+ L
; u) ~/ w7 n! s( M
  if (num-cars > count roads)
. n4 i  F, m" j9 ?  [
$ x, T! V. [" M  ]' H4 p- Y    user-message (word "There are too many cars for the amount of "; T3 K1 y3 L* j9 D( t! ]$ J
                       "road.  Either increase the amount of roads "
* S( {5 `, x5 {7 k! e& _                       "by increasing the GRID-SIZE-X or "$ O: X- K( h# Y% _  I
                       "GRID-SIZE-Y sliders, or decrease the "" }0 b! G1 B6 G
                       "number of cars by lowering the NUMBER slider.\n"0 ~" C3 V3 F0 e9 ?6 h; s2 S
                       "The setup has stopped.")! T/ W7 ^0 Q7 T! x/ d; J5 {$ u
    stop, N5 C) s1 E$ r5 E) S1 O& w+ B
  ]
1 E8 l+ l2 T$ E- j: D9 ~- e  l$ e& l7 A0 O- E) @3 I# I5 f
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
  [' X& u" z+ p( F" V  crt num-cars" j7 P8 l8 [: l' l" T9 z8 G8 D* a
  [
. Z# R7 @/ o1 A# Y' U, a    setup-cars
8 A% V9 S" D3 w. G# ]5 o0 W0 g    set-car-color
/ I, T( S& K! S5 L    record-data
1 ]8 K+ R% p$ i( L7 T* T7 N. D2 r+ f  ]7 c( x- P9 O# m% }3 N  n9 \0 q

/ a% |+ \2 Q9 _; E5 G4 V& @$ I  ;; give the turtles an initial speed
) Y1 r: {2 i* G) _5 _1 [  ask turtles [ set-car-speed ]
+ S  E! \& t0 W; i& R" v; ~
6 y8 T1 P1 H( C2 T  reset-ticks
( }/ q9 k2 @; w- d9 A2 Mend' e! o( [4 [+ d: a( g+ A9 h
* E# Y0 T2 K: |' F) Q! q% \
;; Initialize the global variables to appropriate values
* S8 n. c" l" Z# ito setup-globals& |) H1 [7 g# n! q  R" b6 k
  set current-light nobody ;; just for now, since there are no lights yet! q& `' [  z" I% M2 _  `7 G3 P- X
  set phase 0
& C' s4 N/ ~& J+ ?1 M  set num-cars-stopped 0
2 a( U- r# S. n$ p  set grid-x-inc world-width / grid-size-x0 u* l. g1 I) x% z+ K
  set grid-y-inc world-height / grid-size-y9 z2 N+ A8 T% h' N  Z$ ?

9 A. q8 J; O) D0 Y8 V  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
- V5 e' f* K2 Y4 k/ e4 Z  set acceleration 0.099
" j; K  S3 \. _; F3 M* f" ~% z0 k8 zend
2 V) P: ]7 |1 f) Y) O/ Z1 Q& a
) B/ I( K- y) S+ T;; Make the patches have appropriate colors, set up the roads and intersections agentsets,$ D5 b* B: S, y1 J
;; and initialize the traffic lights to one setting
. S: I; e' d/ a0 Ito setup-patches
+ n! R2 @- Z) {5 Q  ;; initialize the patch-owned variables and color the patches to a base-color4 K+ R# c- \& F# ?
  ask patches
9 N( J5 p4 j% a/ J5 Y  L  [
( ^# z" ?. H2 z6 d" U( J    set intersection? false; L0 q! ?& s3 H! Z) I0 {
    set auto? false
9 D, e& ]* Q& A, q: p$ n% W$ w. _    set green-light-up? true
4 }, T) ^1 V. `$ F/ B+ t/ N    set my-row -1
0 K: Z' m+ k& A! |    set my-column -14 v7 G. m  `9 f+ o
    set my-phase -1
: P$ q+ j' ]6 ?* y    set pcolor brown + 3
# J% Q# z$ @. N* R* O. c7 _/ @  ]
$ n* X0 k) q* k  x/ ?
2 A% ?, o  G1 A; A: Y0 L/ F; |  ;; initialize the global variables that hold patch agentsets" I% ~. b) f+ @# D( P
  set roads patches with  k% j9 g; U+ C- F+ X8 B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or# @0 X2 t& w# @
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ a) a& B! L% [0 ~
  set intersections roads with; Q2 v6 z9 T9 [6 ]
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and6 Z( Y( r2 m! a
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 P! u7 W9 s) @! ?  v9 \3 N4 n

. W3 O2 m: N9 C& e' S5 B3 z# z  ask roads [ set pcolor white ]2 Y* P; ^/ P6 h! X
    setup-intersections
# K9 T3 `6 w1 H2 e3 R! L5 Cend
8 c' r& K+ d* M其中定义道路的句子,如下所示,是什么意思啊?0 B3 b  E) I  _
set roads patches with
/ Y3 ~9 s' X6 u7 x    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, @' w" O, W) p" T    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 ]7 G( E) h  w+ _, ^$ }( y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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