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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。
4 E3 m+ s1 V1 x: x2 q* U# Vnetlogo自带的social science--traffic grid这一例子当中,/ h$ c/ d7 @- B8 M& _8 y, c1 a
globals! j9 h6 W' A2 w: d
[9 c9 z4 r: q' |: r
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
& k5 b7 K7 {! t7 Y  grid-y-inc               ;; the amount of patches in between two roads in the y direction+ ?: g' V1 n3 q
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
* w! C$ z: R& J                           ;; it is to accelerate or decelerate
0 P+ p' @+ Z- f- M  phase                    ;; keeps track of the phase
& h- j! K- n( y! w  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
' q8 N* r; r4 S' ?6 S  current-light            ;; the currently selected light
1 n# k5 ~1 I6 |9 b0 n' g1 A6 N9 [% M0 t1 v- D
  ;; patch agentsets
  E& H$ k( s1 w- w5 z* w& D% E. h  intersections ;; agentset containing the patches that are intersections
2 Q$ g0 |* b& l) B  roads         ;; agentset containing the patches that are roads
4 A/ J5 `6 b% ^8 ]9 X/ i]
5 M' d0 N0 w. _
! o4 p% t! w, S  Zturtles-own% @6 |, z" @: z0 V! a
[
+ K2 l, a; g, N, \5 {2 \  speed     ;; the speed of the turtle( J. N' o3 N( Z. w, W! I7 X0 R
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
* m  ^: M, g) ]: |9 ?6 P  wait-time ;; the amount of time since the last time a turtle has moved: Y5 I) r6 }- u) h% {
]* `9 h" g$ E; E" s  E5 z3 u" Y
8 i! W' k- x' r2 n  G) }9 e
patches-own( z* H. R- d0 y3 T- k3 C9 J
[
3 X, v' c  X: N  intersection?   ;; true if the patch is at the intersection of two roads
) g6 E* U5 u) m: p% v- \! i( h  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.1 B: F3 Y4 n' t8 [4 P3 u: p$ L
                  ;; false for a non-intersection patches.
- w5 u( I. D# l  my-row          ;; the row of the intersection counting from the upper left corner of the
1 X. A4 R+ ^+ X6 A6 {                  ;; world.  -1 for non-intersection patches.: d# G7 ^6 ?$ J  {3 S+ X
  my-column       ;; the column of the intersection counting from the upper left corner of the5 V2 |8 o% ?& P
                  ;; world.  -1 for non-intersection patches.
% J; q; X) }5 l) F. n% Z  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.' U/ t5 H! C( k7 F6 a9 ]8 D. b
  auto?           ;; whether or not this intersection will switch automatically.8 K5 I: K1 f, Y5 J% u8 J. t
                  ;; false for non-intersection patches.
4 F, c) g5 s; c6 m]
+ T( A! ^! Z) |8 i( g
( @2 L3 x4 r0 x9 {
# {% N/ B2 p% X* k;;;;;;;;;;;;;;;;;;;;;;
, S" P. n/ L3 W# M# k8 i* _  M;; Setup Procedures ;;4 _/ z6 f4 n- f: T+ F
;;;;;;;;;;;;;;;;;;;;;;  s) }2 f7 C# z8 g, H  A( L

. x, c& m7 j  E+ v* y;; Initialize the display by giving the global and patch variables initial values.
7 \. O& o8 P8 S( z8 d* i3 g;; Create num-cars of turtles if there are enough road patches for one turtle to
& I# x2 C, u+ _( D;; be created per road patch. Set up the plots., c: z0 d2 ~  E
to setup7 u8 k2 {$ [* ^# B1 b: q& f$ s6 ?
  ca2 c/ P1 t! C, \, E6 C9 A
  setup-globals& o8 f) J  T" \2 Q& M
: Q5 X$ u: }; v
  ;; First we ask the patches to draw themselves and set up a few variables- ?% j6 H# d2 {4 [
  setup-patches5 u- y) z0 V- I: g
  make-current one-of intersections
& z: u1 T2 ?/ J$ |3 A# f  label-current
. {+ G6 ]$ C% I- y8 ^. ~8 V+ E! n: i1 }8 b: T2 J
  set-default-shape turtles "car"
5 m: k6 M2 |& k, w# \) K! o4 P& W- B
  if (num-cars > count roads)& @, M# P6 ^" U+ }- }. e% s% w
  [
$ a7 d' P- f& E& ^; g; \5 Z  ?    user-message (word "There are too many cars for the amount of "9 d, q: E7 E% L) O1 ^2 x2 C* o! G
                       "road.  Either increase the amount of roads "
# @8 \+ z' o; g! Z& l  D                       "by increasing the GRID-SIZE-X or ", D  f5 H$ [3 K; `5 u
                       "GRID-SIZE-Y sliders, or decrease the "
- R: \- X+ C' X2 y/ {                       "number of cars by lowering the NUMBER slider.\n"4 j# J9 d5 T, \! m7 j
                       "The setup has stopped.")
1 u9 ]% y4 s5 a7 }    stop* h3 h5 I$ f" v0 {* I4 C2 I% n
  ]
9 K; n% S) c: c2 W4 U. p6 V" }1 A$ M6 u
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 O/ i1 c! [! i5 }' o7 T
  crt num-cars, J# B8 u( [0 [' ?5 J
  [
( p7 O$ g) v; e! ], Q4 O, v    setup-cars% j) n$ d) a. [# n
    set-car-color8 {3 Z) U/ G  S' m. `% J
    record-data
7 B+ ]5 C+ w( C+ O0 V# Z0 M2 @' z  ]
8 ]2 q6 L/ @2 n7 o  O
, b. {- J& O. L  A, @3 j) x  ;; give the turtles an initial speed1 N! I  u/ T2 Q  z" m  Y3 _
  ask turtles [ set-car-speed ]
, |% v' g& ^0 Z$ G6 `0 S5 K; K1 T# K# N$ x8 }7 p$ i( F7 w
  reset-ticks
$ m6 t. J' W! tend
  d0 W! G5 Z: H% T0 a
/ S' w  {0 K& V;; Initialize the global variables to appropriate values& I- @: o- i( |/ t" k
to setup-globals& U3 f1 a9 B, }6 M
  set current-light nobody ;; just for now, since there are no lights yet3 E0 e# A9 z/ ^" P. ]0 U
  set phase 0
+ F5 _  G4 b6 {( c; J! W  set num-cars-stopped 0( [, a' g( h% U. [
  set grid-x-inc world-width / grid-size-x$ q( n" o9 V% ]  u2 I8 C3 o
  set grid-y-inc world-height / grid-size-y9 P. b. v: Y' e+ D
- ?5 P4 d4 n. s9 P4 j
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary4 `3 |4 j( e6 ^
  set acceleration 0.0999 A+ _3 v, |# b  A3 `  h, F) E6 w
end; I' J/ W. [- e% f  a0 K
( u* J3 R0 g3 s9 c
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,5 C/ i  O3 q! h
;; and initialize the traffic lights to one setting1 h& U/ B" d4 u6 L4 E- u
to setup-patches
7 a" K5 |5 q' C* Z  ;; initialize the patch-owned variables and color the patches to a base-color) P* R' ?; O( Z6 w
  ask patches/ D) I2 p8 @. k1 ]9 Y! B
  [; Y5 E$ C" G) G/ ^9 N
    set intersection? false
# J# I& _5 t) `4 C) z3 ]9 B. n    set auto? false+ J7 E8 e: T% `1 {+ _& p
    set green-light-up? true
2 i2 n" I6 z. \3 M2 L- z* B+ A    set my-row -1' F# m) }  \7 s, ?) \
    set my-column -1
+ E9 `6 o: O* V) R- U" P7 {  G    set my-phase -1  l/ S; `" Y4 N$ C& X7 n* |( Z& L
    set pcolor brown + 3
' Y2 y" v: f1 v2 ^# Y  ]
1 _, W/ N0 p9 B1 U
% _4 p1 I# S% {. t% E* k0 Z9 Q! E2 j  ;; initialize the global variables that hold patch agentsets) ?  _, ^5 p5 O
  set roads patches with" w9 ~# D2 z2 b9 p/ [4 i1 t
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 c7 o/ z% d4 M5 p. J7 P    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* ~" L, Q& o  D( u# {! m
  set intersections roads with
# Y- ?; F8 k% g( o6 k    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
! M) o1 A( W; Q" P# S! S9 B    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. n0 d0 h. T4 i# ^/ D2 L

9 G; R% }( f( p4 S6 F4 S  ask roads [ set pcolor white ]
' k# }, e1 J- U$ _; i( X    setup-intersections5 r  ~! S7 U  M8 I/ Q, t
end- [6 n; Z6 g0 @' ?5 v
其中定义道路的句子,如下所示,是什么意思啊?
# n* v8 ]3 N/ [9 R) \ set roads patches with" q2 o2 u, J0 h% R, C8 M
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ m0 e  r: N. y' o$ D/ f2 P
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! C; g0 N3 W' X( b- z% B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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