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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。6 q% C& p- X9 G. R4 l
netlogo自带的social science--traffic grid这一例子当中,& N( S6 P" I: m' w9 X" n3 l0 V
globals
# t- I0 j* r5 D% @2 I! O8 p3 E[
4 R2 O0 @, r$ j0 r7 j1 j% {  grid-x-inc               ;; the amount of patches in between two roads in the x direction4 S# h/ c% Z6 M3 Q' a) K
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
) ?; }6 R$ J2 [* `4 X' r  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
* y- |. F; q: E/ m; V' T                           ;; it is to accelerate or decelerate
3 h6 m% j7 Q, F- J  phase                    ;; keeps track of the phase! b7 B9 G! J7 Q, G
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure- f- M: M/ l) R$ o5 M, Y6 c- N
  current-light            ;; the currently selected light
" P' l& |/ k# K! T/ D5 ?  R
5 U; _2 u7 J! E  ;; patch agentsets
2 a5 C/ S# e% d; @) R6 I1 \  intersections ;; agentset containing the patches that are intersections: F3 X) v' ^9 j9 u
  roads         ;; agentset containing the patches that are roads
7 ?; d( }+ A5 t5 g) q]
$ C* m  w6 `% j, }' O. ]2 t, o: Y1 i& e) Q
turtles-own! E4 b$ I! j3 p$ ~8 Z: v1 ~" t
[
' B% c# q+ v# |1 J& D  L; Y  speed     ;; the speed of the turtle0 N( [: g3 K0 D
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right" u3 X5 k2 J9 P" t' P; L. x
  wait-time ;; the amount of time since the last time a turtle has moved) o' _0 R5 y) U
]5 h, O1 F; r- C6 a; f
# u& \! x( h& Y( z: V0 F* Q
patches-own
8 l+ b% ?% A$ ]" l. o) l3 H[
% \3 ^9 d. j# _7 j! `: ]  intersection?   ;; true if the patch is at the intersection of two roads
% P7 Z& t) Q0 n) a3 [* v, U# T" F  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.+ I, ~  G) `7 T' H+ f% g
                  ;; false for a non-intersection patches.& v% B: g. w9 Z# u8 o9 c, v; Z% N
  my-row          ;; the row of the intersection counting from the upper left corner of the
0 ^. L; I" D! f( T# p" Y! {( `                  ;; world.  -1 for non-intersection patches.
6 M, C' Q1 }, w) K& r  my-column       ;; the column of the intersection counting from the upper left corner of the( I. p4 x5 m  L6 E. Q
                  ;; world.  -1 for non-intersection patches.8 r. ^6 V3 }* c( |
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
% B% \- ]+ X; _3 L- c9 \1 F4 V  ]  auto?           ;; whether or not this intersection will switch automatically.$ M( u! @3 T! t% m
                  ;; false for non-intersection patches.- l/ w: B9 Q2 ~& T
]3 W( M* x0 \* `( N) D
2 W% Q% O( F+ A0 L2 H

5 l* u2 E  V  V5 P;;;;;;;;;;;;;;;;;;;;;;( ~( p! @* }# g: m. i6 s+ q
;; Setup Procedures ;;  N) ^+ g2 Q4 W" Q2 O5 _
;;;;;;;;;;;;;;;;;;;;;;
# n) Y' f) q* E# T
1 M7 {2 z$ q0 \* H& ~! f3 m, X;; Initialize the display by giving the global and patch variables initial values.
- T- a4 [! n& f/ k2 x( V: n;; Create num-cars of turtles if there are enough road patches for one turtle to: d3 ^# O8 r8 U3 V% W
;; be created per road patch. Set up the plots.
  {) H* X! g" ^" X% \, cto setup4 l0 ^3 Z2 a0 T! s( G
  ca5 ~! c$ i% p% X' |: @3 t3 \
  setup-globals8 B! p- w  X/ T( q4 Y' S

# n5 i& |% ~: G! h% Z2 X" _  ;; First we ask the patches to draw themselves and set up a few variables
2 o3 {# k8 j' p" ]+ O' d  setup-patches
. @& ^# z- ^* I' N% c  make-current one-of intersections5 ^; V- {7 S/ i+ g5 I+ m) ~7 k6 e# B0 O
  label-current
% t7 w* L9 l: A( n+ D; ~! t3 n
# l4 D- p8 f7 i# s2 \1 V# {  set-default-shape turtles "car"
, w+ Z/ u4 V1 |! l7 h& z+ ^; _) I7 J0 h3 `
  if (num-cars > count roads)
% k. z$ ^. K* i+ J! }  [
& v* z  r1 F# y$ n    user-message (word "There are too many cars for the amount of "' W( \, n6 e/ o- F: n1 v3 x
                       "road.  Either increase the amount of roads "+ Z8 b1 e! U" R8 x7 m
                       "by increasing the GRID-SIZE-X or "
& M1 u7 `% a7 f+ u                       "GRID-SIZE-Y sliders, or decrease the "
9 j  B4 n2 P  l3 u. j8 {  @( Y% E' X                       "number of cars by lowering the NUMBER slider.\n"# ~: _8 c3 A) M5 Y2 y
                       "The setup has stopped.")/ `# }$ r) ^* Y1 }  z, \
    stop
: e( G$ r  d( J  ]
" `9 x0 v. F( Z" b8 |& M0 S3 I0 L# V! Z4 g4 X, C
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color3 p5 d" k3 h; H# H& Q0 q
  crt num-cars
" Y0 I  I. d- _. @+ ]  P, g  [, X6 `4 _" D% C) r6 \5 i5 t
    setup-cars
1 I" d+ u; }( K0 P/ r1 T    set-car-color* ~3 ^( e! ^. ?$ _& O$ j
    record-data
7 _+ D8 a+ [2 q  [3 M$ M: p% `5 r7 B  ]! D: p9 G1 U! ^6 @/ ~# ]4 }

% h2 O3 j0 Z0 q  ;; give the turtles an initial speed* D; H& _7 \3 N$ D, }+ q4 x
  ask turtles [ set-car-speed ]0 w' v9 D; W5 B
. c. Y! a; R) R
  reset-ticks
5 \3 l3 z! O1 |7 L9 zend+ C4 d" w- B0 G) g. d! ~: f3 T
, D/ h6 X" R. I5 n1 [
;; Initialize the global variables to appropriate values
' N" Y; `, w. H9 j( `* O! ~to setup-globals( p* b3 A$ q2 k+ z- Y
  set current-light nobody ;; just for now, since there are no lights yet
, M4 S' {3 t, w( Y8 {  set phase 0
& y' ^  l, z" D$ C8 {' v# f! {  set num-cars-stopped 0+ B  m& E( g  ?1 L! D( I
  set grid-x-inc world-width / grid-size-x
$ J2 ]2 K  e6 c: P, S$ k  set grid-y-inc world-height / grid-size-y
  n+ a' C  R3 {' {) O9 A; k
5 V7 `5 y) N, u  K9 @1 B6 R0 ]  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary' F9 p2 i& E& i3 N; [) V
  set acceleration 0.099. b9 w: @0 Z; F9 j
end
6 X1 S2 n9 E. {/ a
' g1 ~6 o, [$ J4 u;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
0 p( Y1 W# m3 L; J; R' J+ w' y' C;; and initialize the traffic lights to one setting
* j, @+ w( r/ I. ?& I6 ]& b, \0 Pto setup-patches
: e' x  M% U% V+ Z  c* }( e5 Y& c) R+ M  ;; initialize the patch-owned variables and color the patches to a base-color
' D3 ]+ j  r  Z( V( z4 A$ K, O  ask patches
9 }: n( D! d' T, u' m0 I0 p  [) H( h$ G$ M; E/ ]/ ~: X5 r8 t
    set intersection? false
9 s& P) [3 O* I4 ~0 {/ {2 g2 x    set auto? false& Q6 l9 |# u% X# u5 b) c, a
    set green-light-up? true
. s6 C' X% I2 u- a% _    set my-row -1  J" o8 P0 `7 ]+ N9 y! G$ A% z
    set my-column -1; T4 q, n8 n3 v8 q8 q2 h5 M/ e
    set my-phase -10 J# n5 n8 T7 F
    set pcolor brown + 3- v4 G$ {# [! g& @) u3 @
  ]  \* _+ g. N: N+ Q

' e# L; Z' g$ V: Q! {( q6 P# c  ;; initialize the global variables that hold patch agentsets
8 {: s' p- K, x  set roads patches with
- T  k* E9 Q7 G# D  Y0 @    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 d6 b; L* ~1 a9 A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" r4 F# ~/ y8 I# O) E/ g, e
  set intersections roads with2 j" l0 v' b3 b! a- l6 d
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
" ?. }0 k+ `( E7 s0 m' x0 Q9 @    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& ?$ V/ W2 X" Z" c# a2 C+ G2 b  K( C2 l4 [7 `  W  P
  ask roads [ set pcolor white ]" W. D, |. E5 `7 U! j
    setup-intersections
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其中定义道路的句子,如下所示,是什么意思啊?" U( o/ M3 E; C% g
set roads patches with
: f# U7 v# a+ K4 x3 X    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 C) i, U3 i! O5 X
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 n5 Q9 h8 V8 T" r
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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