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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。  K3 I; a7 d! e
netlogo自带的social science--traffic grid这一例子当中,/ ?9 a/ y# P, y. P: v" I
globals
+ ^2 z8 j. x$ r; S% [/ h[
* l: R# \+ I$ U2 I4 y  grid-x-inc               ;; the amount of patches in between two roads in the x direction6 E5 G& H' s) W: S5 @+ x. ]& |' I
  grid-y-inc               ;; the amount of patches in between two roads in the y direction! }! I7 j% {" a7 l" S, U+ C
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
# r# V, ~9 O! @* \6 A$ k5 w                           ;; it is to accelerate or decelerate( N1 W. p$ ~% k! M4 t; f
  phase                    ;; keeps track of the phase8 [1 A- o% O* j+ C# k
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
1 M5 {- i. S) `/ y) C  current-light            ;; the currently selected light- s, P: r; }1 G

- R& Y. T* ~  D9 ^  ;; patch agentsets
* r* U: u( k0 t$ x7 ^8 w' s/ p  intersections ;; agentset containing the patches that are intersections
: t+ y4 H# A7 f3 `  roads         ;; agentset containing the patches that are roads
/ S4 T5 i. L# b1 K( i# G) s]
6 B7 o/ V, J3 b  t0 |4 q( d( V0 A9 |6 J. U2 u  \
turtles-own4 c1 t- N* a% t1 O2 k9 b5 I5 U
[
2 j/ F- p1 H) x: K" }  speed     ;; the speed of the turtle1 S+ g$ D: s8 t( g7 s- w% n1 O
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right9 k. {( N9 l7 s/ @5 Y0 b  @
  wait-time ;; the amount of time since the last time a turtle has moved
9 u- s2 Q% j- a2 @5 z]  U' H+ V) u+ E0 W5 m

& R) ~1 r0 ], o9 Ypatches-own  [* O1 }1 U& V, r2 a5 m4 R8 A
[  k' P+ K+ d) x. K% z2 w
  intersection?   ;; true if the patch is at the intersection of two roads: P& E( e/ {+ R1 J( a3 ~
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
4 k. Y4 x& G# u) J                  ;; false for a non-intersection patches.8 f( L; o4 n7 y) Z/ }
  my-row          ;; the row of the intersection counting from the upper left corner of the9 }  a) T" e9 z/ F' ~* q8 o
                  ;; world.  -1 for non-intersection patches.
& z( Q& w8 V+ l+ l  my-column       ;; the column of the intersection counting from the upper left corner of the5 Y# ?, ]0 C2 r% @8 D" s* k8 ~1 K
                  ;; world.  -1 for non-intersection patches.
5 Z# o& W! O9 ^9 i7 a9 D  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.; h1 X1 c" K' C; R
  auto?           ;; whether or not this intersection will switch automatically.* _, m) T  J3 O, o0 {
                  ;; false for non-intersection patches.5 `  p4 K3 F. L3 L  |7 K$ N* h3 ~! Y) m
]" I. f5 j; v5 K0 o8 R7 r. J: L# m

5 I) N' P1 ]  P( M) Y5 f$ w# Z
& u8 z8 z* @: J& [3 k& @& W, s;;;;;;;;;;;;;;;;;;;;;;' f! D3 z$ u7 ^( E
;; Setup Procedures ;;
" C- }1 \, O  `1 ?0 c;;;;;;;;;;;;;;;;;;;;;;5 T5 S: M$ x- P; s

8 g" ^4 s& Z7 R0 Z;; Initialize the display by giving the global and patch variables initial values./ m. t+ u9 @4 W: Q7 Z( L1 C
;; Create num-cars of turtles if there are enough road patches for one turtle to
5 d- C. Y7 ]7 N4 t1 o! s; U; Z;; be created per road patch. Set up the plots.2 @) g8 r4 p! u8 O" n
to setup
5 Q6 L/ P3 P9 }  ca+ ~" x1 h8 d9 s+ Z4 F# R( Y) ?4 p8 C
  setup-globals7 t1 l9 b" D/ ^# F. D; l
0 v- H# e7 C3 c3 Y
  ;; First we ask the patches to draw themselves and set up a few variables
; t4 d; _+ I. j2 E& |6 T6 B  _  setup-patches" W+ Z7 w) D, E
  make-current one-of intersections
1 m- e9 F9 w% ~1 Q4 e1 `  label-current: X" S# n4 o( p: f5 E( Q/ }. c, n1 r
  v. c7 i+ f; a6 f6 m
  set-default-shape turtles "car"
$ l5 {; Y" P, a: L! B8 h6 j; f- i5 h0 y6 G8 E. ^
  if (num-cars > count roads)2 `4 m* u, c4 p4 o$ L
  [6 ]5 a5 U4 z2 r) _" O% X7 l
    user-message (word "There are too many cars for the amount of "9 X6 ^- m8 b6 P
                       "road.  Either increase the amount of roads ", }, V/ r: j1 }5 b
                       "by increasing the GRID-SIZE-X or "
2 x3 D6 P( s* e# |0 V                       "GRID-SIZE-Y sliders, or decrease the "
/ M' {/ |! x! T/ y5 v                       "number of cars by lowering the NUMBER slider.\n"
  M7 |( s; |: d                       "The setup has stopped.")
. r; M: X  x+ ~    stop
- }7 g& p% S7 k  ]2 D- S- w/ I/ E# C

! {# A7 Z- W- e2 W5 B  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 Q8 F3 ^% R; L& z+ i2 T- y+ b8 B
  crt num-cars0 M' u; o. z+ K( y
  [
7 b: B+ G/ {- h& ~! ]" p3 I    setup-cars, i5 p7 G8 K' d4 h
    set-car-color
& X5 M* k4 m. `6 Q    record-data: Z3 J" j  O# ?4 J5 H0 J
  ]+ x: l4 e7 o  w' A! P) Z( V0 t; O
, Z7 ]7 U, Q' [9 Z$ O
  ;; give the turtles an initial speed6 w4 @) E) N: W+ ^1 Z/ t
  ask turtles [ set-car-speed ]6 H( T% {- ^: G; `% X0 A
9 X5 B) f1 S% @6 _/ `7 w: d( S7 P
  reset-ticks
) r9 a' z; W* d+ `end
' G- R* {0 i1 j2 h
5 D5 L3 k7 D. m2 C7 R;; Initialize the global variables to appropriate values
0 k3 W; Z$ q' a, \4 Nto setup-globals
8 e7 g+ L4 f6 y  set current-light nobody ;; just for now, since there are no lights yet
7 Q8 c2 ~: T( }  set phase 04 T1 ~  O2 ^# v6 k1 f" `  W
  set num-cars-stopped 0
3 J; c/ e, a9 e: z; y$ u  set grid-x-inc world-width / grid-size-x1 [1 |4 [& q1 ^9 U5 H4 G1 i
  set grid-y-inc world-height / grid-size-y/ ~9 w' N2 N+ `2 w  v- e
* O! O/ ], S; m- U5 T4 Y
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary1 Y: X& u+ x! l4 y
  set acceleration 0.0998 q; ]! a; R  W" f; Q( `0 E
end* I, O9 I6 L, B

* `# Q, R' b. @;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
2 E0 v5 ]# V6 O7 F. C;; and initialize the traffic lights to one setting
# a: Q. J; @, A% e  ~: Mto setup-patches  B5 y% [: ~6 B# n: o# G
  ;; initialize the patch-owned variables and color the patches to a base-color; @9 y. P& x0 D" `: d
  ask patches. \- [, @6 N0 Z
  [
- m! G7 v' G: {    set intersection? false
1 ]4 X& K: T& z1 d9 g4 Y; F    set auto? false
9 E% v3 h" x" _: u, f7 v2 J    set green-light-up? true" m. u& B" H) _1 \* I7 Y
    set my-row -14 Q# U( X3 R* P. x
    set my-column -1, n4 D. `& [4 E; m9 @
    set my-phase -1
5 a# d% d( ~, B' o    set pcolor brown + 3
3 W. m+ D8 M. z  ]7 E7 H# G* h. c7 q7 Z. f& O
6 R! R5 b. l. w) R
  ;; initialize the global variables that hold patch agentsets3 U, j% K  [/ ]  U* q1 B
  set roads patches with6 w7 C5 Q9 Z2 E1 m
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 H4 {3 a+ B7 d+ a& o& V    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! [$ I+ p# I8 H* J: V  set intersections roads with
: b6 S7 F% y2 z+ q: w9 f    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
7 E' t5 {3 D8 V; R% D  b    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) x8 }8 C+ t' u/ c+ \& s& w1 b
/ U# W# D9 w7 B+ b* F' [  ask roads [ set pcolor white ]
/ M8 ]2 p: o2 K$ ~. |! f    setup-intersections
+ ^* _% O; r- M6 x3 eend" |2 n/ K. {/ C. R: q$ m) R
其中定义道路的句子,如下所示,是什么意思啊?
& p; ~8 l1 B! \ set roads patches with
4 Y/ v$ o+ t$ H1 q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( j9 Z5 \  g3 i1 j
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' z* y/ B: z2 N: }0 H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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