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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。
8 k1 n6 D& q/ I9 ~( mnetlogo自带的social science--traffic grid这一例子当中,
* a- Z3 n) Q" u/ j* l+ ?globals4 l6 @/ P' d: `$ p$ G3 {
[
- @  z) Q" Z! n  w: e  grid-x-inc               ;; the amount of patches in between two roads in the x direction5 x/ D" D0 t( ]
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
& }+ j: w6 c& I& ]' W' v" ]  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
4 p) r! [1 ^6 F. o$ @3 [! B                           ;; it is to accelerate or decelerate
8 \; m2 i/ B) J; f1 B  phase                    ;; keeps track of the phase6 b3 |' x0 S' G7 A5 k" G2 [# m5 v; N
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure* C6 r. q6 A9 p* F) p2 q: e
  current-light            ;; the currently selected light
9 j( u/ I( ^7 U* M1 H  ]/ [4 {" d) j6 @8 |& L
  ;; patch agentsets
2 h% l$ M4 h* q) a, @1 g4 \7 h  intersections ;; agentset containing the patches that are intersections/ l$ {* M8 C$ h
  roads         ;; agentset containing the patches that are roads
; B" w% X8 R) H6 ?! M# m# ^1 D* _]
+ g. [) W/ h' p2 S+ o& @& d% O( {8 k$ n$ \2 U! ^, n. k) r" T
turtles-own
! a/ \& a  u3 ]6 e& ~* o3 {: A! d[
, m6 i1 W4 s3 c& Q9 u9 u# O  speed     ;; the speed of the turtle
6 A/ z+ A5 h+ j- p* W  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
- J4 u  I9 d% c% C- |  wait-time ;; the amount of time since the last time a turtle has moved4 x( @" n, g' p2 S. b) i4 T, Q
]
5 y9 ~( a4 \7 u. ~+ W- l$ d
/ u- {1 Y8 ]  {: A! ?) Vpatches-own% \+ I  E' w- Y! i. a4 c3 ]; g
[5 X* P1 D% D9 t; Q9 l0 P# J
  intersection?   ;; true if the patch is at the intersection of two roads
; G" j" L" b% j6 z  green-light-up? ;; true if the green light is above the intersection.  otherwise, false., u/ O" G2 m' f9 Q' P  x
                  ;; false for a non-intersection patches.
3 W# o- t" I0 K8 |( A  m  my-row          ;; the row of the intersection counting from the upper left corner of the
0 |8 E& d. b6 ~! z' `                  ;; world.  -1 for non-intersection patches.
: A0 H1 e% f5 |' G7 a, k  my-column       ;; the column of the intersection counting from the upper left corner of the
/ O0 r. o" i) V5 x" [0 i! H                  ;; world.  -1 for non-intersection patches.5 I. |9 X  u" ?0 l' ]8 o: ^) g, o4 h
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
1 N! H: E$ M8 E- v  auto?           ;; whether or not this intersection will switch automatically.
" s* C; n5 ~* ~5 `. B2 Q$ P9 [" Y                  ;; false for non-intersection patches.* K, l8 @' k) [# A
]
6 \. f0 x' e1 e; U9 K2 a& l7 D4 S
  \3 e/ i. o2 Q' v9 F, a
5 o  v; F  {8 u: x: f;;;;;;;;;;;;;;;;;;;;;;
& S/ x+ A3 Q5 \/ {4 q7 O6 [;; Setup Procedures ;;
' |4 Q5 h/ i* @;;;;;;;;;;;;;;;;;;;;;;6 Q" d9 X6 K9 C1 s

/ E* ?) i; P0 l2 \9 I- D2 K4 Q;; Initialize the display by giving the global and patch variables initial values.
5 D1 ~& c+ F: Y* c' h* K  ^;; Create num-cars of turtles if there are enough road patches for one turtle to
0 h: c8 Y+ H; `;; be created per road patch. Set up the plots.' c2 Q& B2 m- G9 g! l5 e
to setup2 S+ E: S# [/ X# x9 I
  ca
# r: ]8 t1 v/ k4 V1 q( E  setup-globals9 w  h& ~+ d/ j, a$ t2 ?( h
2 {" p! s% N% `6 n5 s
  ;; First we ask the patches to draw themselves and set up a few variables4 U$ W0 A2 @7 t
  setup-patches
! d% P' P' p$ ~5 w0 n: }/ I  make-current one-of intersections( d3 ]0 W' Y# j* r' |9 w/ L" o
  label-current
# ?/ t4 G  }) l, e+ j) O  g3 C  N
& c: D- Y) d- E/ G  set-default-shape turtles "car": I# a; ?6 j4 \0 P
1 _2 Y/ x* t% u/ t7 W) V
  if (num-cars > count roads)/ u' w3 I" ]# [$ W6 Z
  [8 [( E0 E  w5 i6 \0 K
    user-message (word "There are too many cars for the amount of "
0 q! y( ^" Z) Z                       "road.  Either increase the amount of roads "
4 z! n  Q+ q6 E. h                       "by increasing the GRID-SIZE-X or "
+ S* K2 M9 M# w; t7 @3 S: v" e                       "GRID-SIZE-Y sliders, or decrease the "9 T. \4 B6 e4 I( r/ z& Y# y
                       "number of cars by lowering the NUMBER slider.\n"' V  N) ]: P) j" K# ?; s- y7 y
                       "The setup has stopped.")
- }. m% _3 X( [. j" B1 ^2 s+ n1 q    stop
) n: a; M5 R5 y# l+ @, L8 F. t  ]
. }, r$ z- h2 N, A" h. @) Z3 t6 g7 L( s+ c7 u6 u
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color+ y4 Z+ g6 }5 X
  crt num-cars
+ f0 B, ^( M& g7 }( L  [$ i" X( `( ?2 B* |
    setup-cars
+ s% c. J  b* B1 J# h5 |- \    set-car-color
& `& S  ~, _: o4 ~3 Q+ G    record-data
8 f- Z  ~2 }/ M  ]: |4 y- |3 O) x

. \/ d; n# ]2 d6 }1 C! S+ x  ;; give the turtles an initial speed
, q/ o& T- E3 }  ask turtles [ set-car-speed ]* u3 [* U! n  `
, P5 w6 [5 {, X4 f9 y
  reset-ticks' L* M  o* \3 o  m
end& `$ b) t8 j% {9 n# T
$ y" E" J& p- G# c0 E3 F& Y
;; Initialize the global variables to appropriate values
) N8 u: J( T2 t$ F- a2 N- t/ H' Nto setup-globals" Z; v% J& O' y  f# G0 r
  set current-light nobody ;; just for now, since there are no lights yet
" N0 S4 S3 o1 S& W/ p  set phase 0
' K4 n% m; e* ?: R# Q7 Y, Y+ s& ?  set num-cars-stopped 0
( J# b" y# N! m  set grid-x-inc world-width / grid-size-x6 x, h8 \% T- l+ R6 `8 K6 i/ s
  set grid-y-inc world-height / grid-size-y( V2 m# d6 O3 H# j1 M- X
0 S3 V* p( \) A% p) `" Y
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary0 ^* G" O6 N2 R, A7 \
  set acceleration 0.099( Y$ M- E- a- E: F% O5 U" g* S
end7 w$ {8 ?2 r  z; h8 U" f
) P- w' X& N4 d% a4 G6 l( A
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
; o4 ~5 t( j7 D3 f! s;; and initialize the traffic lights to one setting
' I/ Y& n& t9 G$ T  s2 ~to setup-patches
6 j- E% E" A3 W4 ?( y  ;; initialize the patch-owned variables and color the patches to a base-color
/ N! N" U+ v* v: O6 n5 Z: S+ E  ask patches
( j! F0 j2 ^# z  [  h/ |! F; u9 L" s+ W1 ?6 N' g, R
    set intersection? false( Y2 {4 Z+ B0 S5 g+ D2 r, R
    set auto? false3 M( m' q2 n% k- f
    set green-light-up? true. W' p* U) K" L4 v
    set my-row -10 D5 C# r  \% @; x
    set my-column -1  J4 t. N  u/ {8 j" y+ A
    set my-phase -1
( b, k6 q% X" L0 N# f+ \* S    set pcolor brown + 3
# ]1 w/ [# Y4 G& l  ]
! V3 q3 X) Y/ r0 p) ^( {& _# b' c, j' x( ~
  ;; initialize the global variables that hold patch agentsets/ s  n! D: |/ P7 L
  set roads patches with$ R* J2 ^- e: f% S8 X: Z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, e9 o% y4 {, A; K; z. |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 Z9 {7 u1 c7 Q
  set intersections roads with" X- p6 b" E- p
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
8 U3 F  R; F" r+ O8 v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) Z* s. s7 q7 l+ k+ r4 f. g3 d4 J0 x, C# Y  W6 F
  ask roads [ set pcolor white ]
4 l1 b& g2 U7 v9 A; I) [: F: O7 g% {    setup-intersections
% H& E7 \* G% A5 d2 t7 C6 tend! b. V6 E+ V; t
其中定义道路的句子,如下所示,是什么意思啊?! p/ _& @$ |1 C1 G" u7 ^
set roads patches with
/ @1 L+ L1 H6 ]2 v  x" Y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ {0 r* `" v" e! i- I* p: W3 |0 m    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; i' ^6 Q0 O5 N0 p* Z, p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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