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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。
: l+ ~! y" g! K' x7 J+ C( znetlogo自带的social science--traffic grid这一例子当中,
5 }7 {. f0 h' y, Jglobals
: F- T+ F) O9 D  u0 h[
4 m) O4 @+ p, ~# [/ I  grid-x-inc               ;; the amount of patches in between two roads in the x direction9 h- G2 S8 j* i! v: A5 u+ b$ X
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
' A# \2 k1 e7 d  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
9 x  Q# s  `# x- s# ?9 ]                           ;; it is to accelerate or decelerate
+ Z1 {8 G& c: C6 d  phase                    ;; keeps track of the phase- D5 I$ @" F7 v, ?* z
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
0 G% z9 [2 V7 {8 s( c  current-light            ;; the currently selected light2 u/ R9 G1 q% T8 Y0 K8 T4 d

6 x1 p  a) {* K. r0 e  ;; patch agentsets
& f" w& n6 A. m  intersections ;; agentset containing the patches that are intersections9 i) a1 W- L" Y. a, v7 O
  roads         ;; agentset containing the patches that are roads
9 K6 n1 h- J% D% b3 w0 U]
$ a9 [* Y, q9 @
. q! b9 J& S* H! J* n: zturtles-own
. N% S- h0 Y- A1 T3 K! |[- b! z) Y& V, o$ g" H% _2 F" W
  speed     ;; the speed of the turtle
, F9 D: e+ A: w3 Q  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
& Y: c  X+ [+ Q4 u! X/ X  o% W  wait-time ;; the amount of time since the last time a turtle has moved, b, X& Q5 @0 L  v
]
0 u9 W- U9 [* p  B9 L
# a3 L, B$ S- c4 Cpatches-own2 L! t9 U3 d9 y3 H/ i
[* [! x% S6 I" j8 R, c
  intersection?   ;; true if the patch is at the intersection of two roads1 J" S# `/ U* B) k8 j/ b! ?( T. g
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.# l- H* c' ]; Y$ {
                  ;; false for a non-intersection patches.# T: c4 B9 q& Z# Q3 i
  my-row          ;; the row of the intersection counting from the upper left corner of the
) ~# K, h2 B/ b( H7 D3 G                  ;; world.  -1 for non-intersection patches.
% c# j- T$ o1 r6 m$ ]! q" ?  my-column       ;; the column of the intersection counting from the upper left corner of the( a  ^) h4 `& _! S- y
                  ;; world.  -1 for non-intersection patches.. a9 ?' p( k. z2 W  J9 e( |) C0 C
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
* ?# x, ?2 s) O0 e3 |/ i  auto?           ;; whether or not this intersection will switch automatically.
5 }- l3 }3 ^+ g( o                  ;; false for non-intersection patches.
8 R) K8 z/ J9 C5 E6 a; c: }+ B]8 K6 a  B& e+ w& @9 c. q8 q

2 O( _6 I2 r8 |& M, [1 B4 C4 g- ~
;;;;;;;;;;;;;;;;;;;;;;$ D! C1 \) N- [& k
;; Setup Procedures ;;* o/ Q1 b" m: g6 F2 o
;;;;;;;;;;;;;;;;;;;;;;
' Z" ^; E1 ], |& C% `) L8 [7 C  ^+ p
;; Initialize the display by giving the global and patch variables initial values.
( {9 }2 S( \/ g7 i5 M" \8 r/ _;; Create num-cars of turtles if there are enough road patches for one turtle to4 A. \6 d2 k# ~: m1 x# y
;; be created per road patch. Set up the plots.
6 x# p+ o. i7 `2 p% `to setup
7 \. i# \7 N0 e/ D  ca$ U- ^  z" [, W$ R* _/ F
  setup-globals5 n9 i0 j$ J' I" j/ H

7 k. r5 Q& K* ?2 a0 b5 |  ;; First we ask the patches to draw themselves and set up a few variables  {4 p+ h% b3 B9 |5 F% Q, w
  setup-patches
, N% T  p0 a1 t$ f6 Q8 o  B  make-current one-of intersections1 T* d% `, `) m$ S  j
  label-current  P4 M& N1 f- d% E. V- |; d& \% |
3 `. c6 l( V. @3 D! H% |) R
  set-default-shape turtles "car"
8 o) Q9 p/ s( M1 }6 L2 X% O# P: }, p& z
  if (num-cars > count roads)- n% \4 ^* p9 [1 y' z8 J
  [
! ^* b+ Z; |: ?( n) y1 k' B    user-message (word "There are too many cars for the amount of "
) J7 X! J0 s0 r/ ^6 ?7 `! W9 D                       "road.  Either increase the amount of roads "
8 x- H/ W) v1 S0 X4 `7 {                       "by increasing the GRID-SIZE-X or "4 K4 V9 }: C* g
                       "GRID-SIZE-Y sliders, or decrease the "# @  o8 o9 B% }3 ?
                       "number of cars by lowering the NUMBER slider.\n"
! Y% f# w2 V5 Y/ o: B! N                       "The setup has stopped.")
5 @* c# ?8 k# E1 c* J. D    stop
/ b( N. |9 {+ T& Y0 a8 b- q) b: E  ]9 p+ W+ q! c- ~: [  [  V' a$ f$ j

3 j" b$ m. k, d  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
2 c' g0 A) ^  H  crt num-cars
1 V$ s' O9 U8 y" a% X7 W  [
& |& P  g. b) Y3 N1 g# X3 |; V    setup-cars
3 h0 K8 `. p; z0 ]    set-car-color
1 [: A% J- w" v    record-data
1 _6 l8 A9 ~; B  h  J# }, [  ]9 j; I, |$ o2 g  y' N# w# e/ d

4 B! C" T) G2 T' J0 u  ;; give the turtles an initial speed
7 {$ |6 r; B7 p* {. r  ask turtles [ set-car-speed ]- [3 o8 W8 h' U6 p) N6 k
" x' o4 _; b+ C
  reset-ticks& y1 ], H, v1 B( I
end
( U$ G( l2 e/ j' G, U; _* B. K- [( i  n( a" ^  [! f
;; Initialize the global variables to appropriate values% t0 F2 k' A9 Y9 S! K7 V
to setup-globals
7 S3 i/ L" E9 k2 G# R  set current-light nobody ;; just for now, since there are no lights yet
% J5 `' ~% L( t1 O. ?" o) i  set phase 0
% X0 A9 G- w1 O4 U8 P  set num-cars-stopped 09 d4 [! M% W# x) i& S& T1 q% i8 b% s
  set grid-x-inc world-width / grid-size-x$ l2 R1 I# C) `% z) |
  set grid-y-inc world-height / grid-size-y
+ \9 X1 i2 J. M/ z' q$ {4 t4 R
! ~% ~3 ~  S. H2 L# X' |( ]8 ]7 g, R  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary1 N5 t. S! H8 r! r8 f. g
  set acceleration 0.0994 P; R0 p- p  R: q- h# a
end0 C' `: S$ v8 L

2 u9 f* O: U, o6 Y1 M: x;; Make the patches have appropriate colors, set up the roads and intersections agentsets,& o. F1 E- }8 t! Q
;; and initialize the traffic lights to one setting
, M+ H- n3 ?" y; |2 bto setup-patches0 y# l7 u! |( M3 r" G' z7 |
  ;; initialize the patch-owned variables and color the patches to a base-color
0 _/ s) S3 c% c% D  ask patches% Z& y) U" j9 p7 X. u
  [, C1 L4 d/ X' P9 F' e6 \
    set intersection? false
5 h3 L/ D$ u7 Y* Q) l    set auto? false
9 D4 n: m1 y7 v" S2 @    set green-light-up? true1 y0 f9 ]/ B: [4 x6 r! [6 k4 `
    set my-row -1+ r+ ]+ k/ F3 l( a. g0 q* J. L& ^
    set my-column -1
: D8 {# u3 ]! i3 w& b9 z    set my-phase -1
8 i* M; ~" u* A; [9 d8 _    set pcolor brown + 3
# X3 D7 n0 {$ s  ]. `" r, t) H, @0 E

6 V( P* _- {1 H+ g1 J5 E  ;; initialize the global variables that hold patch agentsets9 ~1 p% _% Q6 y4 n3 k% b' N
  set roads patches with- Q" T) W* X) d8 g& S
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 V" _4 r9 i, a6 L  P
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% C) X7 f4 j6 ^- e, M5 J2 ^- I" ?  set intersections roads with
' u# ^0 d0 x. s- Y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and7 ?, o/ n$ a4 n/ V8 G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 J% Z4 S, b2 O- L
- X- T, Y; y0 A! v! {% U% q
  ask roads [ set pcolor white ]* Y3 C5 H+ u) y/ r$ o# [5 k
    setup-intersections' `! z- V9 m$ y. M4 B. R
end7 Q6 L4 O0 V. i7 C9 C( S( _! b, n
其中定义道路的句子,如下所示,是什么意思啊?+ |4 ~7 c' ?8 ]1 `& s$ V+ S
set roads patches with% L: A. i; F6 C" {
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* |& L: B7 _9 J2 i& E2 V+ g& _; g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ N# I( N9 u7 M  }  q2 |$ k$ n) N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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