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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。0 \0 g8 ~5 t, Q9 c! f
netlogo自带的social science--traffic grid这一例子当中,) j" n) M4 I- x' ]% D. r' N- b, s
globals
! x* w- S+ C6 Z/ S* m7 }[
; p0 s: E3 x9 \5 _$ c; u+ ?1 K2 ?& s  grid-x-inc               ;; the amount of patches in between two roads in the x direction
$ `& u! {! d! w( a  grid-y-inc               ;; the amount of patches in between two roads in the y direction- f7 ^1 D( v1 N
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
, s: Z) }' M, Y' G8 e+ B0 g                           ;; it is to accelerate or decelerate
0 A0 E" X% Q/ L5 y  phase                    ;; keeps track of the phase) v1 e; q9 o) \7 ^& a( J
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
+ v8 `3 Q  U, H0 m9 P- p! m" t  current-light            ;; the currently selected light
2 T9 t8 {6 e: ]! u' ^. K0 J& @! Z, C
% W# K* P' e, A2 w2 t  ;; patch agentsets6 y! w! u, J9 K3 f0 F, E6 A
  intersections ;; agentset containing the patches that are intersections2 ~) w: T! f, g3 k+ @/ J- @/ \
  roads         ;; agentset containing the patches that are roads1 l- q1 i; H& J) Y
]
! J3 R8 A& S, A- P0 Z0 Y  n/ L& Q" x. O( g0 |7 m: x' @
turtles-own! u7 G+ G2 {9 l  ~$ m: E% k* _1 E( l
[
& j) V0 q. _2 ?, k+ \3 G  speed     ;; the speed of the turtle
" e8 y- z" m, F% ^$ w* ]: J8 k, D  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
: ?7 x# Q9 D0 _# p% B8 f  wait-time ;; the amount of time since the last time a turtle has moved2 a$ b: }- j* i9 C% O# G
]: C7 o' B; b- F

4 ~1 C6 `2 e6 R. n9 D2 {2 ~: P9 spatches-own
/ K7 t& V- g: m5 H& M[3 \0 k4 f8 `# \
  intersection?   ;; true if the patch is at the intersection of two roads2 W0 P/ f& L$ q' _/ N
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.- ~# X2 A5 @/ C! t7 G
                  ;; false for a non-intersection patches.
1 C7 |3 d' M! i# b: Y; n  my-row          ;; the row of the intersection counting from the upper left corner of the% L0 U) G* e8 u, G, s. X
                  ;; world.  -1 for non-intersection patches.  l* k) ]5 S7 s9 p
  my-column       ;; the column of the intersection counting from the upper left corner of the
& E" x2 w$ Y) j/ Y3 ~5 b                  ;; world.  -1 for non-intersection patches.6 [- d' a% D' r% `( j9 y, T, \
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.  l2 E: n: u9 e; Q% R0 n% g* v
  auto?           ;; whether or not this intersection will switch automatically.
, c+ Z: F4 S; K; B  i. m0 }                  ;; false for non-intersection patches.
! F" \0 X2 p1 f- j! Y/ A. W( K]
, S2 \8 \/ Y' s* p, G% t# E
% d4 \' l8 X) Q& ^' G4 J& d8 e! z8 ~7 Y/ E- ?
;;;;;;;;;;;;;;;;;;;;;;
/ C  L- {2 ?. j# j+ U;; Setup Procedures ;;$ }4 J* g% R$ S6 V, p
;;;;;;;;;;;;;;;;;;;;;;4 r  j1 D4 q2 I: S  z

- ]7 K8 N& s, _$ {$ z;; Initialize the display by giving the global and patch variables initial values.
) Z- K* p0 |) b% P1 \;; Create num-cars of turtles if there are enough road patches for one turtle to
2 P# ?! ?1 C, m' m3 k* k, o7 K;; be created per road patch. Set up the plots.
+ Q: L9 u- U, rto setup9 t# ^' d+ i& n# F+ g
  ca
5 w% e' m- ?5 B1 S: i5 A  ^  setup-globals* x! J+ i  @; ^4 S0 [5 a8 S* ]

% N' S2 a5 F+ A1 i' F  ;; First we ask the patches to draw themselves and set up a few variables
, r+ n" ^% B* M6 N& P3 e  setup-patches
; i' o" E( a! T* o3 e7 c5 W  make-current one-of intersections# w6 {% ]6 S4 a; Z, \7 [
  label-current8 o7 U: B/ E2 F$ `) S

: C  z8 f% D5 \+ L  set-default-shape turtles "car"& Z( b$ \! a4 s8 M

/ J' a0 b" O! K/ U; L  if (num-cars > count roads)
' T& L! n1 i* x* S! w) _8 _  [3 {- g  J" @4 g& Q# D1 P
    user-message (word "There are too many cars for the amount of "
9 A  z) P( u) `/ Y& e8 |  z                       "road.  Either increase the amount of roads "
$ A  A+ M8 C1 I: c* W9 W                       "by increasing the GRID-SIZE-X or "
6 h* v7 E; }$ \5 c% ?& v" W                       "GRID-SIZE-Y sliders, or decrease the "* h' Y, c. [7 R+ ]
                       "number of cars by lowering the NUMBER slider.\n"7 z7 D- b& u+ L# T( O, V0 O
                       "The setup has stopped.")1 T  \3 _% E- `7 P* s( x, Y  T
    stop
. {# D* k# d6 y; u9 X. W& U  ]4 U0 t2 h9 M4 {; p6 E' ]; l/ |* w

7 X4 W7 O  Q- a2 E5 g  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color8 d* N' X/ Z/ ~& F3 F  b
  crt num-cars& y4 w+ x# W5 N' f
  [
  z" F0 X9 n0 Q! l- x6 G    setup-cars
. E7 W7 }% Y" |3 j; W+ Q" L+ P' q    set-car-color
, a8 ~  k3 x/ `" l0 J& |& a# J    record-data: \, @+ b( p6 P" D2 f# p
  ]
* A  {5 `  L6 ?- m; i3 K% R% t& i+ @+ W
  ;; give the turtles an initial speed
' ]7 \% I! }- h; d) x  ask turtles [ set-car-speed ]
1 n4 [3 i, @* N; Z# u3 j/ N; @, d1 H3 s/ g7 {2 Y& I% M
  reset-ticks
0 ]+ g: A* S. _, I7 o" a+ D' B8 M" \end0 T& `8 x$ F. Y+ d6 |# u
; e5 e" i6 q6 f; N! y, \! M! X2 \
;; Initialize the global variables to appropriate values$ `7 {8 k8 {) x. a
to setup-globals
8 y& e6 ]5 u- T  set current-light nobody ;; just for now, since there are no lights yet
; D% s$ @2 ?+ b0 S  set phase 0, M8 e+ T- C) l8 ]
  set num-cars-stopped 0
1 S0 e9 {  y9 e- z, ^  c! E; n  set grid-x-inc world-width / grid-size-x2 F2 h( }2 M8 B8 Y+ h. X9 l
  set grid-y-inc world-height / grid-size-y
! F' m) i( N: i9 `! t/ }* T3 D
2 a5 D, n% i5 P. Y/ O! u4 j  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary6 p2 k  W# {' j# D' o" ?& A" R
  set acceleration 0.0996 ]9 e- u. u. K8 s3 t) R
end
% h2 `4 ]& t4 f3 v" A7 @& F' L
' k1 p0 G2 ~4 z;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
2 }7 O7 n2 v# O6 N: A& F) U# M;; and initialize the traffic lights to one setting
) |+ T3 x2 |& f& M7 Hto setup-patches1 Y# R& L1 E$ M$ \
  ;; initialize the patch-owned variables and color the patches to a base-color
0 A" M& H( O5 H/ b# b  H' y7 }. U  ask patches
9 w; ~/ G) j  q/ j& O8 Y" `  [
* ~3 N2 u' ^" w) F7 [    set intersection? false# Z5 r5 C, k7 Y* H8 ]
    set auto? false
# o, g* j6 L3 {: m2 `: X    set green-light-up? true( }! C6 U8 A+ w0 r
    set my-row -1
% g" b! I7 f0 f* F' o. F9 C' Z    set my-column -1/ [) J( y% N' g6 x' i) W2 E
    set my-phase -1
* H/ W9 ^+ _7 d6 S: `. d    set pcolor brown + 3
/ }2 m% N& g* o( |* w  ]( w! O5 L7 x$ K: a6 W
5 B- {, \" R9 y; M1 Y4 c  V
  ;; initialize the global variables that hold patch agentsets) U5 @+ z: p: [. p* n/ {- z8 P
  set roads patches with0 h2 m2 J/ }; h* R, Z3 \: H: _  A9 R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' F5 v/ A. L3 ^
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' ]/ g! {; a# M( E3 v  set intersections roads with' {: n+ h6 l; f: q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
- Q8 c4 ~0 `5 T& W6 h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" M# a# A  c$ }/ ~- ^

! _' n9 L& h' N5 ~! R7 \8 P  ask roads [ set pcolor white ]
5 h6 g. a0 i; F    setup-intersections1 `4 {; e% |. Z7 H  Y& C: `1 N
end
0 q; ]% ~* H4 y其中定义道路的句子,如下所示,是什么意思啊?5 u) z, y; p) R5 g+ s2 Z, T" @4 l
set roads patches with) a. \) O, s  ]3 @* h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 A1 L0 J5 I: R8 x; p    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ J  r6 ^; }6 A5 r+ s
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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