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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。
  q" l8 V& t- }( j6 K' snetlogo自带的social science--traffic grid这一例子当中,' |' `$ p  g. P- s: N7 M, F" z
globals
5 R. O9 o; I9 ?1 T[# ?! p# }8 z" X1 O3 \  O8 i! c
  grid-x-inc               ;; the amount of patches in between two roads in the x direction6 j7 Z7 z4 R% e* ]
  grid-y-inc               ;; the amount of patches in between two roads in the y direction+ ]. p$ j7 r7 d8 a, w& s; G
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if+ @% ~' c0 A+ Y9 c! V
                           ;; it is to accelerate or decelerate3 t- J7 y! m' `/ x1 u2 y. Y
  phase                    ;; keeps track of the phase
) P  g- g; }! M! g* A2 \" E% ~  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure. L6 S, r% k6 o6 v
  current-light            ;; the currently selected light
& \6 g- Y& h7 i' f& j' a' p& O0 I
  ;; patch agentsets
: l/ F, @7 f' z+ `9 G  O) m5 L  intersections ;; agentset containing the patches that are intersections
+ A1 F$ F7 W2 x; w  roads         ;; agentset containing the patches that are roads
  P9 g- i; L" @+ E: x]
; B' w8 _  q" ]  D9 ~1 w/ B& I' L! ~* {  v$ }+ q
turtles-own5 X, h5 V9 G, O) `
[9 p7 j4 r$ j/ Q
  speed     ;; the speed of the turtle: m1 ^7 {3 b" Y9 Z
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
, b9 m0 o3 n! Z$ r( Q  wait-time ;; the amount of time since the last time a turtle has moved
/ Q- H2 a- |( D, M: F]7 H2 T8 [& J9 `( \6 K& T1 [) W  n% A

6 @0 J& j0 i; i7 F9 @, C/ zpatches-own
$ \4 U" X3 |( S[) M* I  Y' e6 I7 l( b, u8 D
  intersection?   ;; true if the patch is at the intersection of two roads: Z9 q. X5 W0 p
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
. i1 L7 P; Z+ R* |  J2 d2 e                  ;; false for a non-intersection patches.- @4 i4 N  r) `9 A
  my-row          ;; the row of the intersection counting from the upper left corner of the
6 Z* i7 w+ u$ ^4 \! |+ i4 F' W                  ;; world.  -1 for non-intersection patches.
' U( U/ S( u# q1 q( ^+ d  my-column       ;; the column of the intersection counting from the upper left corner of the
1 ?- I3 Z0 j0 o( S" Z, S$ C! A                  ;; world.  -1 for non-intersection patches.; X: |# a, L  T& g3 _+ D: W
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
' c, |1 O/ H' S0 u' F( p  auto?           ;; whether or not this intersection will switch automatically.: Y+ U' J7 z( {
                  ;; false for non-intersection patches.
0 ?. h8 u; p! R2 z9 z]0 R" P5 ^' E9 K2 d2 ~

! t" U& m( M2 Z; r% }0 t: f9 ]) n6 K' q& y3 n7 a" t( Q
;;;;;;;;;;;;;;;;;;;;;;
+ A% [% E5 ?1 |$ k/ M" p;; Setup Procedures ;;6 ~6 f$ ~+ l" D% J  ^
;;;;;;;;;;;;;;;;;;;;;;
& K& I# u+ v! c9 Y) Q. R: U" M' H+ ~. B0 Y
;; Initialize the display by giving the global and patch variables initial values.
% A8 x' F* L( {- V+ H9 ]+ `;; Create num-cars of turtles if there are enough road patches for one turtle to) z% t7 v* ?" W3 U/ `1 K3 H
;; be created per road patch. Set up the plots.
' s0 g$ B: o+ }/ q7 T& Fto setup: ]6 @5 S3 D; P
  ca9 C% C$ ?1 B4 Y& M; n
  setup-globals
' N& F: R- C1 N
' z+ r* V% |% V1 B/ t% s( ]: m4 x$ E9 I2 G  ;; First we ask the patches to draw themselves and set up a few variables
0 P) C4 Y4 c+ v2 v  setup-patches) v* v- ~9 k, x
  make-current one-of intersections2 v, v) }. R( H
  label-current4 h! W2 l" {. ^9 D; ]5 X; T

) O% _5 w7 ~5 X( @" e" h  set-default-shape turtles "car"
- g. w$ e( {- }6 |+ M
: s( n9 [# B& \: ?# G8 |  if (num-cars > count roads)
1 x' f* D; {4 L! g, m  [
% y4 O2 U2 q& B7 S; `    user-message (word "There are too many cars for the amount of "
# H' s9 j  g2 ^0 p                       "road.  Either increase the amount of roads "+ N& v1 }5 a) p/ U- i/ p' a9 O
                       "by increasing the GRID-SIZE-X or "2 y) t" H8 R& q! N, z
                       "GRID-SIZE-Y sliders, or decrease the "% ^2 [; H/ `* I7 Z+ w: ~! K
                       "number of cars by lowering the NUMBER slider.\n"
9 A/ e# ~7 C' b5 q  @" J                       "The setup has stopped.")
+ I) N, ~0 M+ {    stop( L1 u6 p+ F( ~! O& F9 E+ D
  ]3 L  m8 l$ I' C, L* h4 ?9 z
$ o) o5 V& P9 I; G8 a! W( |: q
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
" f, P9 d/ m7 H/ ~7 O2 a7 \  crt num-cars
- Y3 I% _5 `! [  [8 J8 ?8 s! C& z, p' q
    setup-cars
. l& X3 _5 k" L7 x6 e0 I    set-car-color
: N3 o$ U. R+ a- s3 L- H    record-data8 g, b2 K+ V! u' e+ b
  ]3 a& ]1 ]* w- t" z2 U1 [
* R3 j+ M" b' {5 i
  ;; give the turtles an initial speed
3 \0 [6 n& q9 }; d- S  ask turtles [ set-car-speed ]
; x$ M0 L' T2 u& X) \3 p) u3 u9 e; z) V* e- H8 F& A5 F
  reset-ticks
8 @0 L6 f9 V: C# ]. c' Dend
4 s9 C# Z1 z  \$ x1 R/ y6 v. l* s* j% m8 u
;; Initialize the global variables to appropriate values* b0 Y! b: @5 w$ M, Q. H
to setup-globals& J4 N8 X/ D( ^# i' ]4 q! t
  set current-light nobody ;; just for now, since there are no lights yet
1 o( I2 m% r2 J; K7 N8 Z' ]# c4 R  i/ \  set phase 09 t5 O4 ^+ B- H( @3 g% M2 r
  set num-cars-stopped 0: L0 G! B8 ]; T
  set grid-x-inc world-width / grid-size-x
, T' W* R+ I0 s  D  set grid-y-inc world-height / grid-size-y% |$ ^/ J+ F' A( C8 j
0 _$ ~" w- k, w+ w, Z9 V$ v! k
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary4 B( z. ~) p: D: f' v
  set acceleration 0.099
+ B4 W! z# Z, R/ I  S+ `5 B/ x2 gend
$ K4 }( s3 _: w3 G" Z* c8 N( L. M7 k, g. ~7 G7 T7 ^, a/ P% w2 ~
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
3 Q' d2 z( M) L/ ^;; and initialize the traffic lights to one setting1 s8 H; o5 Z8 V
to setup-patches. n' o: Z1 y' x
  ;; initialize the patch-owned variables and color the patches to a base-color3 D0 L4 s0 m# b! n$ e
  ask patches3 \) M% k) N- j" |8 L1 O
  [$ z. w- s+ v  X' u. a' X1 c* @9 V
    set intersection? false( Q9 X. F* H/ z0 @* K3 l
    set auto? false
1 {( \& b- m% y0 R- |    set green-light-up? true! M# E, x; s% v. l
    set my-row -1
4 {. Z/ r1 ?& O+ O# c( u    set my-column -1
& S0 H  B3 Y6 u. b& M5 T) p% _    set my-phase -13 E$ r# J, R8 m8 F* Z
    set pcolor brown + 3  b. ], P" {8 B* x
  ]8 ?  M% T5 @2 x# }# _

- w3 u( @" S$ L( _9 |  ;; initialize the global variables that hold patch agentsets; T& {8 I* n6 x* X$ V/ ]$ W
  set roads patches with
" v0 x- V# E- }    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, F; y% m# b( a' j. o3 p4 v7 a0 [0 p    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* K3 E5 Q/ }: Q0 V  set intersections roads with7 y. z# `7 P" Z: i1 Q5 @9 z0 l
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
" m) I- r; t& Q- p    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: A% o  _- |4 ~) D5 A+ g* L- b

" o7 \' C9 W% G/ x, p; r# J  ask roads [ set pcolor white ]! U8 T0 @& F& T+ Y3 H
    setup-intersections
. q8 G$ |# N7 G. M. ~; K; Kend4 |+ K" A! B) w2 T* f
其中定义道路的句子,如下所示,是什么意思啊?
& e0 I3 {0 W/ r$ e set roads patches with& f+ J% {' o8 z6 y" _& I
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 Q( ?8 k$ ?1 y8 t4 V6 U& a    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* d+ l0 V; d" G" B8 b! o# Y* 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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