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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。# y, |8 x+ Z5 u7 ^' p2 e
netlogo自带的social science--traffic grid这一例子当中,
' b6 J9 z6 k, v! p' y% Lglobals
1 H% P" o# Z7 ]& O5 m: M[+ P9 O0 @9 q" V" \* @
  grid-x-inc               ;; the amount of patches in between two roads in the x direction5 N2 K/ Y* [' [4 P( c! C5 A: l7 H1 H
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
7 H6 W, O* k' _/ R& Y; r! U  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
6 }, N7 h/ E8 z2 R% ]                           ;; it is to accelerate or decelerate
# v5 y3 @9 v7 G4 n7 x  phase                    ;; keeps track of the phase
- G( b5 K% ~5 I3 c7 r  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure9 E9 p/ A: a& M5 }
  current-light            ;; the currently selected light
6 b* u: Z* p4 A; F
# U$ T+ ]$ r+ s7 g+ K  ;; patch agentsets
# ?& I# H- Y! l! m3 T$ |0 J! @  intersections ;; agentset containing the patches that are intersections
9 ~$ _4 @: Y$ s9 ~, ~& f) S1 x8 w  roads         ;; agentset containing the patches that are roads
1 {# Y$ ^# I; s( a+ d8 `/ N]2 Z/ Z$ u" x2 n% W) D) w

: W. s6 B7 H+ J2 E% kturtles-own
( I1 Q% P" y1 H$ D9 W  J[
2 c* J9 c1 E* ^! b3 Q2 K  speed     ;; the speed of the turtle
) F6 y( n7 x2 s6 j7 p) ]5 a9 h  up-car?   ;; true if the turtle moves downwards and false if it moves to the right9 N3 v3 F4 U3 J1 d0 h1 E
  wait-time ;; the amount of time since the last time a turtle has moved5 O2 B2 g* W* {! ?7 K
]
/ ^; t: W) N! F
! q0 }7 g- p4 s& R: H# G- kpatches-own
: C: ?5 Q/ D' Y6 g( q[
1 W! A* X% f. h' N- s1 g  intersection?   ;; true if the patch is at the intersection of two roads6 t- d1 i/ s4 G  k* U
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.4 P8 t! a  D/ q* P
                  ;; false for a non-intersection patches.9 O+ x1 e2 }  @
  my-row          ;; the row of the intersection counting from the upper left corner of the4 [8 T" Y' ~2 ]& y- Z
                  ;; world.  -1 for non-intersection patches.
2 \9 {& h3 g) B1 }! m5 |, |+ A1 T  my-column       ;; the column of the intersection counting from the upper left corner of the, c% n* l  Y; p6 J) z. o
                  ;; world.  -1 for non-intersection patches.4 a" m% ~/ b0 |& X" C( A% C# r! X
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.8 e% z$ |) R, K, B/ B8 @3 I
  auto?           ;; whether or not this intersection will switch automatically.
& e7 h3 v* h" l                  ;; false for non-intersection patches.7 @. g) d. s9 {5 [
]+ h# x6 V2 U5 b* H- v6 m
* \' N% O/ k; ~9 Q
4 }5 F: O5 Q1 N- S
;;;;;;;;;;;;;;;;;;;;;;
( l. l5 {3 R$ I;; Setup Procedures ;;
. W# U! e8 u8 b2 f+ S0 S3 m: H;;;;;;;;;;;;;;;;;;;;;;+ i6 z0 W6 w2 E& C7 i6 E/ x

2 ~3 S6 Q9 d3 U;; Initialize the display by giving the global and patch variables initial values.9 x+ L$ G3 }6 P6 b. Z$ n7 b
;; Create num-cars of turtles if there are enough road patches for one turtle to
9 [" e9 j& @% H  _/ h( v;; be created per road patch. Set up the plots.& e2 U% g# y; t( o; N. }$ C, z
to setup& U% N1 v7 F; c: x" N& y8 V
  ca" Z9 I5 V: q6 e9 ~" I, t& B1 p6 M
  setup-globals2 Y: U, j' S) F

: E& y; y" v: c6 ]  ;; First we ask the patches to draw themselves and set up a few variables
  x9 f9 o  u$ K  |" [! W. ^  setup-patches
3 ^7 \8 C  c& [, j# v4 e0 [( {  make-current one-of intersections
. M: y1 k9 F& L- m3 P+ `' k  label-current
  a% w+ J& v8 F0 G' X& j( W: n  `8 Z! B; A7 J) y, d2 d9 W
  set-default-shape turtles "car"9 F- H: {* Y7 ^: B: z
- `4 n5 y  j  q$ u# T3 S6 M
  if (num-cars > count roads)( g& ~" A1 d' Z  [+ t1 I
  [
9 Q1 R* R; j8 i- c* r. L: S; G    user-message (word "There are too many cars for the amount of ") B, d' L7 ~8 a7 U0 Q
                       "road.  Either increase the amount of roads "% J5 c) V# y' b. }$ x$ @
                       "by increasing the GRID-SIZE-X or ", @+ W* }. u/ }4 d
                       "GRID-SIZE-Y sliders, or decrease the "1 O% p8 n' X! A7 t$ F
                       "number of cars by lowering the NUMBER slider.\n"0 c3 p4 `( Z9 l/ ]; h
                       "The setup has stopped.")
% c5 _; N$ X3 n; b    stop$ x6 x. S4 `( O; e1 g! y
  ]: U' D# S+ e# m/ @) S8 w
) j' _5 f3 g# d7 ~5 y! }
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color/ U' t# J" Z! C- j4 ^
  crt num-cars3 `" s, f6 \  k& M' M& w
  [) Q* d) N4 u; N- U) K
    setup-cars
+ J- p( F0 E* G% l    set-car-color
2 @4 E9 g) J; U) c9 W6 n; l; k    record-data; s4 e& T, ~0 i
  ]- T) u7 w( G4 ?6 u4 b- s8 M

* r# Q7 h3 c6 a* I$ C  ;; give the turtles an initial speed
! z+ e( `' P4 n$ [) [% j* `7 r  m  ask turtles [ set-car-speed ]* e0 J" P, A( r

1 M. b9 W. k7 J# H  reset-ticks5 e/ J8 X+ J- p$ ~
end8 M: Y5 k; u3 y3 T
1 K; [/ q5 ?( `5 ^
;; Initialize the global variables to appropriate values
9 g  [# m7 k2 U3 g7 ?" h/ Hto setup-globals
* s. }" X& @6 k  set current-light nobody ;; just for now, since there are no lights yet
" @/ Y) V7 J& |0 M3 q. M! ]; h  set phase 0
- q7 A. x- K( n  a  set num-cars-stopped 0
) Z; M" m0 |) _" g) M  set grid-x-inc world-width / grid-size-x3 ]3 l- d0 l: _7 p: o& }8 [
  set grid-y-inc world-height / grid-size-y
3 W0 S- A0 q" N& ^% q1 |  V+ I% m$ A* F* A" B+ e
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary# e! P0 B. J8 t( i; q$ ?' A
  set acceleration 0.099
' R$ e; f* W, }* Fend
% R( [" J3 |7 ?# m1 S
6 \, m. h  I7 V1 {;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
1 Y9 O- I# R8 w( F5 j;; and initialize the traffic lights to one setting5 r+ z6 m6 c2 H' w2 D) D+ y
to setup-patches% b+ M; V& C# L4 r$ _
  ;; initialize the patch-owned variables and color the patches to a base-color
! k6 }% w' Z+ E% f$ D; K; K! i4 O& h  ask patches
. B& f& i4 Y' F, R4 m  [
: e6 F+ U! ]/ F  l* ^    set intersection? false
- A* a4 ?4 }, E+ R9 M    set auto? false
9 J  i9 T6 v2 f9 j    set green-light-up? true
# q4 Y. H2 E/ I$ T5 H; E+ ^# y    set my-row -1
7 @$ B8 |: ^/ }7 v    set my-column -11 H4 L7 y! P" J3 f" f" N
    set my-phase -1
" Z/ U: y5 A: I# F0 H" Z% ?    set pcolor brown + 3) f7 k! d) v, _% r6 i
  ]: Q9 h2 ]" O" ?  j5 v9 t, A) [
7 q3 z2 t6 k- a. K, I
  ;; initialize the global variables that hold patch agentsets% a( \2 X; f$ _3 {; ], x) r6 D& u
  set roads patches with
: W3 I. }8 Z7 w; n+ L    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% z2 |( v& H$ ~5 @0 o
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* Y& r1 D! R* X4 \. x, l/ d  set intersections roads with
1 i8 A- m" N3 W2 S! l    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
! B! m3 j$ O. h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 \9 ]/ F6 P/ \! Q/ j2 h% w/ x5 ?( E, a
  c6 Z! e6 Y- x1 G* `+ s- H$ b  ask roads [ set pcolor white ]
' i0 k* F( K1 t) U0 ~( ~$ a5 u/ ?    setup-intersections0 A, H; b6 s8 P2 J5 ]
end8 M) g4 r+ S5 b% o0 a
其中定义道路的句子,如下所示,是什么意思啊?' [2 i! u5 H8 {! L8 Q" p7 G4 \
set roads patches with& w8 O- W$ |* x. ]) h5 k
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  p$ l" t* |6 |" W0 R1 Z9 u' ^# q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 q( x& N9 G: 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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