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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。
4 T/ o7 d$ h) L, anetlogo自带的social science--traffic grid这一例子当中,4 r6 P: t9 C4 u4 u( {
globals# h+ h/ |" W: g+ Y) z" ?
[
7 R$ X% e- c" V- B- Q  grid-x-inc               ;; the amount of patches in between two roads in the x direction
# J! g. h3 O% G  grid-y-inc               ;; the amount of patches in between two roads in the y direction
5 J3 s$ A3 X' R; S- t5 y  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
' |# Q6 w1 t3 t% V6 p- k                           ;; it is to accelerate or decelerate" T0 _( {9 z% U- d" Z
  phase                    ;; keeps track of the phase) Z' P. @/ G5 {: L& c# G
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
7 e; c2 i+ _3 b  current-light            ;; the currently selected light
( X' |9 ]1 a+ @* m
$ r% A" F) G5 m" a1 [  ;; patch agentsets
0 K* o7 y$ V( }# d: \- `  intersections ;; agentset containing the patches that are intersections
1 S( y1 v  ]: q  roads         ;; agentset containing the patches that are roads! s2 G( q0 Q" a- l- R" r
]
. A% q0 ]% G! y  a9 e- |
1 t& m% }1 Q! ^- @6 @. @  u# n+ vturtles-own
: F6 A+ z& ?; z% B[! T1 s# U/ y  o1 r' c3 ^
  speed     ;; the speed of the turtle# e( R* E! \% i
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right7 z& t: ^8 w* O6 Z
  wait-time ;; the amount of time since the last time a turtle has moved
: h( x5 {/ M9 ^9 i/ g, y' F]
3 F  y# s0 u% M- F3 m# P6 T- p' q' q2 h$ ]
patches-own
! @( P$ J4 j( l; ]+ A5 G[
7 u; w# m& u6 `  F3 _  intersection?   ;; true if the patch is at the intersection of two roads
, a, Z7 Z  _9 j( ^1 t  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.; X+ k% d1 L2 ]5 ^( F+ i8 o* k+ b
                  ;; false for a non-intersection patches.
1 W) M' Z8 ?# L' a9 L  my-row          ;; the row of the intersection counting from the upper left corner of the7 s% f. O  H" \! F& N; L& c
                  ;; world.  -1 for non-intersection patches.: [) `/ W. S! H: |: n
  my-column       ;; the column of the intersection counting from the upper left corner of the1 o* W  G) V* o' E; M
                  ;; world.  -1 for non-intersection patches.! E5 l/ X+ D$ d3 s# B+ ?) P$ T
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.9 ^) V8 w% c; _3 c
  auto?           ;; whether or not this intersection will switch automatically.4 ?" D% s2 X. [2 _- N3 Y7 f
                  ;; false for non-intersection patches.0 n. M% m/ Z- F  h7 [* i4 r
]) s6 y  g; ?1 [1 B' s

% T. I$ N. U* S$ O0 [  H2 E' C; H6 t; i
;;;;;;;;;;;;;;;;;;;;;;1 x* q# C: F+ w6 I# k9 ~
;; Setup Procedures ;;
. d0 t# }+ H8 p( _7 c! S# C;;;;;;;;;;;;;;;;;;;;;;* i3 J7 T6 U6 [. h& ?& X

; I+ V. u( U9 I9 h5 |7 E6 a;; Initialize the display by giving the global and patch variables initial values.( t: Z, e% K3 ]6 H" |( I/ O- X
;; Create num-cars of turtles if there are enough road patches for one turtle to
% A7 d1 x5 T0 x  U; s7 k9 X;; be created per road patch. Set up the plots.
4 F. Z: g$ K+ c0 E; `# B* Sto setup, T4 p  r8 R' q2 s! d' O" o
  ca
2 O4 J7 [" @& v# R0 p% e  setup-globals
% @& X' {3 X) x- B; o/ f
* e  J9 F: H# Q  ;; First we ask the patches to draw themselves and set up a few variables
1 |" T  f; J7 Y  setup-patches' n6 r) D) J- K" R. J+ X
  make-current one-of intersections5 N6 ^: o% c& G' H1 T
  label-current
" k  k3 y( k& f* S$ \
3 u* w6 }0 s; J4 c' L+ f6 c8 f  R  set-default-shape turtles "car"0 ]- T, S# d. ]0 _$ k, ~; \. H8 H
; b- o6 V$ Z' P4 d: r
  if (num-cars > count roads)+ `; z* }7 U% i/ G1 O1 @* k) Y
  [3 o. w! \% f' |$ p$ t6 X
    user-message (word "There are too many cars for the amount of "3 _: g0 K2 V5 V* s3 |5 q8 m
                       "road.  Either increase the amount of roads "
0 ]" U* @- ]3 U6 t8 D                       "by increasing the GRID-SIZE-X or "0 |9 f( `$ Y0 W& M( u7 y7 Y
                       "GRID-SIZE-Y sliders, or decrease the "
; J9 c" p  R  n) b" A% E% G8 k8 p7 o8 J                       "number of cars by lowering the NUMBER slider.\n"
3 V, Y( G: f+ r2 f' P                       "The setup has stopped.")
/ i  P: g; L" l2 ]' _    stop' f) L3 }5 f7 r5 d' E+ L
  ]7 ~7 \! W2 r* d" _% w3 W
2 C5 |0 I# E6 f
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color$ f$ b! f5 X, }6 D8 ]7 w' N) |2 _
  crt num-cars9 d) f  D5 f/ p+ d- ^( I& R( L- J
  [, X. a8 f& _+ E- U! B' B
    setup-cars
! v) Z5 }( ~0 K+ w6 j    set-car-color
7 Y  V" P% E4 O+ P! {! {    record-data
) e$ Z6 g* G* R) ]7 `  ]% W) j8 `5 T+ c

# b- o3 V" O/ s- V; n  ;; give the turtles an initial speed
* N# \3 A. O9 o  n  ask turtles [ set-car-speed ]
3 C5 a7 a+ f# J& W, W/ W: _' R! G% v$ e; X
  reset-ticks! F; t0 T. J( z9 C3 ^- |
end/ o& T2 h/ N0 g6 a" [) R. ]' F

  Q3 Y2 S' D! c3 V- s5 y;; Initialize the global variables to appropriate values
) w& h) e; o. F( d+ A& Cto setup-globals
5 p& s# w% Y' h  set current-light nobody ;; just for now, since there are no lights yet
; ^4 h0 ?7 g. h" e1 x  L  set phase 0& `, s6 U: Q) @6 ^1 {. X' L$ {8 S
  set num-cars-stopped 0- w2 E. \: r  g1 i. C
  set grid-x-inc world-width / grid-size-x- }! L* u+ C; L+ \, ~: t
  set grid-y-inc world-height / grid-size-y5 ?* B% n/ I4 u, n. J/ Y/ V
: B0 A5 ]& @6 u9 e9 ~- t. q8 F
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary: u' h& z, n5 N0 X( g; J+ S
  set acceleration 0.099; R8 [* F/ M* a  g# q
end
- C- H9 d' T1 j) Z6 H. w
9 i  g/ n$ S5 }! O( i;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
8 J$ e7 G# l* O) i) D;; and initialize the traffic lights to one setting7 z0 }5 ^- s% t, ?; a5 w$ d
to setup-patches
7 t$ Z. v+ g3 l/ ^8 s, t  ;; initialize the patch-owned variables and color the patches to a base-color
% ^3 z& x2 S( L2 N5 M  ask patches; G: u0 L- s( {: a7 u7 H0 j5 ]
  [
8 s& G% U5 p2 D+ \6 z0 y% P; B    set intersection? false
3 K2 }  `; N* o' J/ n    set auto? false' D2 I' q+ u4 V: i  e5 |
    set green-light-up? true, h6 Z/ B0 j: J/ d
    set my-row -18 u7 Q0 S! ]: N8 h, w4 j, j% A- r
    set my-column -1
+ p+ v$ \+ ^$ E- C7 Y1 B) j    set my-phase -1% l1 B2 y) S% d; O; Z$ k
    set pcolor brown + 3
4 c. w0 J; {) j/ F2 C! k' S  ]
6 k" R0 R) i5 w: R
! B7 O8 N/ C6 M$ I  ;; initialize the global variables that hold patch agentsets7 k; h/ o4 ?" w3 D3 |' p
  set roads patches with* ]9 @% U# q$ _2 h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* k$ u  d3 M5 z$ \1 z6 m# Q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( G: z( O' z. C
  set intersections roads with
# {, r5 i6 E7 r9 Z( }' K    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
% {2 v$ R6 d; \- X: ^. @    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  J9 p' N  q3 _( m& e9 M' s1 o1 l" @) I
  ask roads [ set pcolor white ]
& G+ f- G6 \7 v& W$ V    setup-intersections$ s3 N' X0 [. A: c' k4 J
end$ T; R% |' i$ v
其中定义道路的句子,如下所示,是什么意思啊?5 g6 T7 o- H5 u
set roads patches with9 |- p( f' q0 x" ^1 f
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" D' V& J! M4 Z0 Q( Q) x7 r    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 _+ \, v* {  }& ?/ B5 }! A! ?
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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