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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。; }- I  y, C. t- j
netlogo自带的social science--traffic grid这一例子当中,
7 ]' h1 U2 I* Z; I, Lglobals
2 |1 Q+ x2 |$ d4 Z9 N) j! u* D: C[% |& _& Z6 }& d( ]  T, e1 F
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
4 R$ i! S! r3 \) h) Q- P  grid-y-inc               ;; the amount of patches in between two roads in the y direction
7 K: x' D- P; j! c( [( u6 r  acceleration             ;; the constant that controls how much a car speeds up or slows down by if: _7 ]# F+ g3 ]4 v
                           ;; it is to accelerate or decelerate
+ x$ u; ~1 N5 R. S- `( }% y  phase                    ;; keeps track of the phase
1 U3 n7 F6 B- I* M+ g, E  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure5 t, i. h2 b; k( ~% p
  current-light            ;; the currently selected light& o; b. i7 @" O8 [
# R" I+ x  U) @# R3 |7 I
  ;; patch agentsets6 O; I+ J# I. s8 H2 U3 E7 v
  intersections ;; agentset containing the patches that are intersections
; M0 m! P" r- o: u  e% D  roads         ;; agentset containing the patches that are roads
% K4 n2 C. b9 Y]3 s7 B  B0 ]( @, x% ]$ Y4 O( T8 d

0 r: B) ?( ?  k; d# Pturtles-own
# i# w$ n+ P: [9 |1 ?[' A, T8 T, g- ~; E$ Q. Q# g
  speed     ;; the speed of the turtle
% b5 g) q) k7 x9 d% M  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
/ P7 A- }+ h1 M  wait-time ;; the amount of time since the last time a turtle has moved2 e  G- l4 C9 _6 }
]
2 d% l, Q! J- x. c
! _# Y9 l3 l8 E3 dpatches-own3 N* Y. D$ r& {) f& j0 P* M
[
  D5 U+ `. J$ S5 }- a8 c/ o  intersection?   ;; true if the patch is at the intersection of two roads
0 M" d) X$ v: i5 v1 U  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
! K8 \  L$ U1 z% x" }8 B                  ;; false for a non-intersection patches.
4 A2 c; `0 ^3 [2 S+ S; p  my-row          ;; the row of the intersection counting from the upper left corner of the
# u& H# @% m  U, B% V+ Z- F                  ;; world.  -1 for non-intersection patches.4 o" W# @( N( h+ U, [
  my-column       ;; the column of the intersection counting from the upper left corner of the
# {) e0 p0 a4 Z/ ^- m                  ;; world.  -1 for non-intersection patches." m* P5 s0 U3 j) H% Y/ |' R& l
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.4 j5 t- R9 K, v# R1 Y% |
  auto?           ;; whether or not this intersection will switch automatically.5 b4 r+ a* C3 ^" \% r
                  ;; false for non-intersection patches.
  C5 N; S# X0 ~$ f/ h8 _5 E' H]
* ^- y, r+ x9 H8 W1 A. m, ~+ D1 v3 Q

* N3 S2 ?* L- x' U; F$ `# z: X;;;;;;;;;;;;;;;;;;;;;;0 i* D# c: M* s0 @0 ?
;; Setup Procedures ;;( S1 Q  ~: q4 Z9 p
;;;;;;;;;;;;;;;;;;;;;;* T4 `2 G+ `& X% A! x/ e& G7 U

% n: X! `0 j+ l1 c$ P;; Initialize the display by giving the global and patch variables initial values.. x( k: u6 m4 c, S* c$ t3 B
;; Create num-cars of turtles if there are enough road patches for one turtle to) b6 o) F- j1 t! W' s
;; be created per road patch. Set up the plots.5 [: p5 w2 {; y, X7 c. G6 P
to setup
* j( W" L- B: |- z; J; q4 Z) M  ca$ k7 S' b; r4 z+ _' `! w: i
  setup-globals
. c/ b" Q2 B: U4 {! h# W/ [- |, L) F0 B9 P$ R' u* n
  ;; First we ask the patches to draw themselves and set up a few variables
. H% w" x  N% j/ d/ Y  setup-patches
1 T1 N+ k3 R( N7 G2 g" x8 Z$ o  make-current one-of intersections0 f. m8 K3 {( [1 J3 w, O
  label-current
8 B; O% H: g+ C5 e' K6 [  D
& p2 A; ~, V: i7 ?  set-default-shape turtles "car"& ], M7 `8 g' H. J  H0 q8 O
+ M6 o! ^' n: {6 Z& S
  if (num-cars > count roads), U3 T  ]/ {7 W3 A2 w
  [- K4 R, K# A8 D% O0 V
    user-message (word "There are too many cars for the amount of "9 q  ?+ a$ V5 k4 }; |7 j5 L7 N
                       "road.  Either increase the amount of roads "
  a0 s2 |% M4 B6 b                       "by increasing the GRID-SIZE-X or "
7 @! t; y: O2 _* P6 T# P0 T" J                       "GRID-SIZE-Y sliders, or decrease the "8 Z* i1 x0 \: J! J7 V% X! n+ U
                       "number of cars by lowering the NUMBER slider.\n"
5 [7 t# x# Z: i1 U                       "The setup has stopped.")2 ^" |4 N1 g( U8 f
    stop$ z8 @- m2 L3 s# o6 R5 x, L
  ]
# J: e$ K' g4 e# l/ w/ n, z6 L% f- K
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
. K" d7 m1 n& }7 N( A/ G) Y  P% H  crt num-cars
% i% e  F' K( T- e) [0 q  [
( [4 b# I- [: `/ I- o* @    setup-cars
4 _0 ~+ }& f2 n    set-car-color
% Q4 h; U' n. {. E  i6 H    record-data
  V  z9 @- p- B" b( K, |  ]
) E" i% I7 B# l7 |# _' n, s" c8 W  O6 l* R7 R
  ;; give the turtles an initial speed
( W; n; T/ G, H3 d! |  ask turtles [ set-car-speed ]
( B/ x, E6 b. g. L
& U$ B5 q0 @4 `" l  reset-ticks/ C; t! ]( b: ]1 [/ y# u
end
  w# \* l9 K0 j1 O. h
, @. k% q: N5 o; Z% w' \3 v;; Initialize the global variables to appropriate values$ m. ]) b& k% W' \8 \' N4 x7 F
to setup-globals
% R; M) D1 s  H1 ?: f  set current-light nobody ;; just for now, since there are no lights yet
' H& H  K) V0 P- P* x. l  set phase 02 T( V% W1 o" S* H/ `' o4 y: X% I
  set num-cars-stopped 0
9 o# J8 R, e- P8 M& R9 y  set grid-x-inc world-width / grid-size-x6 G. x( d' H/ B: K% ]: |, o
  set grid-y-inc world-height / grid-size-y
1 R3 s) u% t& D# l8 T0 M, E: q1 z% Z' E0 R
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary" P+ t# M0 Y" G# s" b
  set acceleration 0.099* i7 ^: ^7 N- E) M' x
end
1 Z3 {- i# k  @
" q' k( z+ p$ v$ ?3 w;; Make the patches have appropriate colors, set up the roads and intersections agentsets,7 p# x& q" {  b( m2 F
;; and initialize the traffic lights to one setting. d% @1 A# H) j0 z0 c9 }# M5 \
to setup-patches
: J" c% Q/ q3 \8 K  ;; initialize the patch-owned variables and color the patches to a base-color: G& v' A* J, x# i- J2 i
  ask patches
( V+ v: J2 ]/ M. e$ D  [7 S, d& k2 t6 h! ?
    set intersection? false
! I* ]9 U5 m+ p  }5 F0 V) b    set auto? false
- P( B5 C3 X2 |( Q  q6 }' }    set green-light-up? true
( }7 }8 @0 a7 q6 T" O: C    set my-row -1
( w; L, [4 u8 i& t1 P# L( D% v    set my-column -1
. [- A* L7 D7 L+ J& T    set my-phase -1
# j% V& N* N* U    set pcolor brown + 3
, I3 ?2 ?1 e1 V: e$ S' ?4 _3 }  ]! [4 V7 O7 G) _
/ N' O. W- A- p  u1 }
  ;; initialize the global variables that hold patch agentsets# D; I3 F: m( C/ S4 o+ T
  set roads patches with
" y" X2 ~7 w0 ?7 H0 A7 A    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 \/ ?, {6 @7 D8 u# t& ~/ D
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 }4 B6 L$ E) v- K, G& x  set intersections roads with
9 C% }" s0 L) [( R. U    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
7 L+ D! z" U; M' a$ Y' k1 ]8 w4 C    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], {0 o$ W2 u4 I4 A

! E; d( T2 N  U$ k  ask roads [ set pcolor white ]7 W6 u" P8 ?; x$ [
    setup-intersections; R+ b( ~2 Z* _+ |) |
end
1 C1 S% e% `* |. F, l+ A3 W! Q其中定义道路的句子,如下所示,是什么意思啊?2 Z' F/ q: u) z2 ]
set roads patches with
! K7 d2 M+ ~+ s2 w, F' i& l    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, [7 r' k; e: c/ ^/ f7 J" m, }5 e
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ D: I2 D% J: @0 q
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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