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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。% e7 X/ I1 C. N6 h3 y0 K) x# `7 K
netlogo自带的social science--traffic grid这一例子当中," l) o5 x1 _, I8 L5 ^, I. _/ Z
globals
5 n2 {  C2 h5 {( ?% Q" V9 i+ ?[
0 U+ g1 e( S- o; g2 N% e  grid-x-inc               ;; the amount of patches in between two roads in the x direction% U0 f( C2 w% c  Q
  grid-y-inc               ;; the amount of patches in between two roads in the y direction. J/ i# N9 @5 S
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if! ~' o" C% m) q0 N5 t; R
                           ;; it is to accelerate or decelerate0 j6 }3 s! r% B1 {3 c; N$ F$ ?
  phase                    ;; keeps track of the phase
. X0 F) M, p3 J: c; }. T  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure, k% X6 Z. ?8 _6 C7 ~' @( b
  current-light            ;; the currently selected light6 M9 N6 M1 u2 S8 m  k

5 A9 ?8 Q% Q/ ?; T) z' F, E  ;; patch agentsets1 Y* d1 k8 d9 O& Z5 o. \2 L& @7 t
  intersections ;; agentset containing the patches that are intersections
: A0 Q: Z/ V; k  roads         ;; agentset containing the patches that are roads
6 d; R% f9 c( T: {% g8 ]3 S% n4 ?]
! S# h; c$ c4 T6 O- a0 d: {; x
* x. f: W; Y- v  V- |- ^$ _turtles-own. m( Q) k: _! t4 |3 ]1 Z$ d
[
8 T- Y9 j( W1 [" {1 t  speed     ;; the speed of the turtle2 y( S5 x0 _! S4 t0 s% h
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right4 x4 y- {3 k) `( h
  wait-time ;; the amount of time since the last time a turtle has moved- Z/ i  f: B* `# m
]4 k9 G! J- O% h4 K6 f
/ h7 b2 D' P( {5 h
patches-own, L- F) \. p- }2 L6 V5 v
[( S, i0 z' P% e# {- Q! S
  intersection?   ;; true if the patch is at the intersection of two roads
( ?: X8 @6 z) C% j  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.) I4 [' h$ I; O3 x9 m- C
                  ;; false for a non-intersection patches.) r. O6 J0 p0 a% Q/ N
  my-row          ;; the row of the intersection counting from the upper left corner of the9 q2 c  L2 h1 e  M, a4 d
                  ;; world.  -1 for non-intersection patches.: w3 ^; `0 r; P
  my-column       ;; the column of the intersection counting from the upper left corner of the9 F- g2 E9 X# q
                  ;; world.  -1 for non-intersection patches.
3 L- @, e$ s3 Q- N, P& e  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
/ O: u% ^  Z$ _  T2 N1 {  auto?           ;; whether or not this intersection will switch automatically.8 v6 x& F7 m, \0 {8 F# I; C. H! l
                  ;; false for non-intersection patches.
9 ^) Q9 g: h8 M% d9 t4 ^, S]6 c5 J9 l7 d$ r; `& x% \; ~9 `
! N! ^2 s  B& s  f& e0 `9 [

( a' r/ v4 Z7 k7 v;;;;;;;;;;;;;;;;;;;;;;, I9 S# E9 A( v" h. u
;; Setup Procedures ;;4 J5 S; L4 D' X2 L$ h
;;;;;;;;;;;;;;;;;;;;;;
' T& M- L: \1 C0 a% w8 V6 S  h( J8 E. b
;; Initialize the display by giving the global and patch variables initial values.9 X% i2 w* g6 Z) h) D
;; Create num-cars of turtles if there are enough road patches for one turtle to
; R4 z# Q; C+ b6 };; be created per road patch. Set up the plots.' ~$ D, S) @% F
to setup: W. k$ _! ^/ `! ]& |! _' q- G
  ca
! |; j1 {7 D" ?) e$ q& S! B6 j  setup-globals
2 O( l5 b/ u; ?1 C
0 v4 Y. z! F1 u5 n" q  ;; First we ask the patches to draw themselves and set up a few variables
5 w6 V* J1 L' k  setup-patches
; J# D1 I& r" j; v) r8 ~1 M( i1 |0 m  M  make-current one-of intersections
: @  f" I8 |! A8 r8 a) m$ ~  label-current; z- ]7 C. i: s7 q

4 y7 q) U1 q  u2 |3 }  set-default-shape turtles "car"+ _- u5 F0 C6 g4 k8 z* l8 d

" c! q2 M- w3 P+ R3 V6 L2 ?  if (num-cars > count roads)
- l! b/ k2 G" z" r- F" Y  [
) Q! H- G$ m5 D; k; m    user-message (word "There are too many cars for the amount of "
: e4 Q, @$ c1 _/ }                       "road.  Either increase the amount of roads "
6 g: S& C$ [7 e( n) R                       "by increasing the GRID-SIZE-X or "
  p8 m, H8 }% P- S                       "GRID-SIZE-Y sliders, or decrease the "
4 Z9 f/ u& h0 |, J9 ~8 T                       "number of cars by lowering the NUMBER slider.\n"
5 \( g2 c* D6 E" a# E7 B9 E4 U                       "The setup has stopped.")
( |  z  n; H. R/ z+ R! o0 s- K. j    stop
3 r# ?6 s, h/ h: `& a  ]
6 [8 R/ X/ X  |( P
9 _. n& ?7 d& C% C" O6 e  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
" h8 ]2 {1 k, _: K" i/ X  crt num-cars- u3 s3 g  L+ e8 H
  [; E+ m. ~) V/ V/ `
    setup-cars) w' X0 I! g3 z; p* Q
    set-car-color
, N+ S) O9 R5 A9 ~/ V+ v    record-data& C5 V- P) r- r1 z
  ]
0 M4 g) W: N6 m3 _* W0 n1 R! ~
2 V0 b8 ~- V( Q1 b0 r  ;; give the turtles an initial speed# M  |8 b+ Q- }/ Q3 e% I0 g
  ask turtles [ set-car-speed ]
8 i+ E5 x9 G5 ?$ T/ |1 b3 w/ }3 L
+ [# q: j+ g/ S7 x+ ?2 N. t/ Z  reset-ticks
, f8 v" M) m- q6 }end
; J! R% O! k1 @% s& v$ l1 y. h1 b( `. ^4 _
;; Initialize the global variables to appropriate values0 J9 j4 d3 s- h, I
to setup-globals
: F- o* Z1 {# D4 R/ J( l: I  set current-light nobody ;; just for now, since there are no lights yet: f* ^1 c0 ]: X6 S2 b
  set phase 0+ R# y% j7 f4 y6 H+ V; x
  set num-cars-stopped 0
+ l6 U- i. W8 p: l  set grid-x-inc world-width / grid-size-x
+ C! i8 P, W& S; m0 e  set grid-y-inc world-height / grid-size-y
$ K: Q6 n8 L1 E  ^
2 A; |" t1 ~; f+ R  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
0 t6 z% ]: E. \# C8 \, V1 x  set acceleration 0.099
: Z& i3 Z4 a% E) Rend4 n  {; f6 q! }( ?$ L
- u( @* Y/ T& [. O" _
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
( m% d4 F4 j' d5 o1 K* v;; and initialize the traffic lights to one setting0 O& D  p2 x+ J# @4 }5 z  S
to setup-patches
& X1 Y  d; G8 v8 Y1 d- y4 A  ;; initialize the patch-owned variables and color the patches to a base-color
: G; l' y( L+ v  ask patches( O/ Y: G7 H, |& }* K
  [
! C" P3 \) J. e: e4 _# e0 I    set intersection? false4 [. S8 |5 e) q
    set auto? false7 u! }9 R4 r6 B! ~' _( w
    set green-light-up? true
3 Q2 L( G! z0 x8 Q$ ?# U    set my-row -14 `( m1 c6 O8 B5 |
    set my-column -1
5 |0 v: x( t) ~, H; Y    set my-phase -1% F/ v5 d, v% R
    set pcolor brown + 3
: k/ |! ^( j- Y+ t. C7 n  ]
# Y8 j% k6 |1 n+ w# f  N* |+ P
3 b) K/ x& ?. d( t# o  ;; initialize the global variables that hold patch agentsets
4 S5 ?. f' ^9 \, x1 D) ?2 G1 |3 _  set roads patches with
0 M- }# n: t8 Z! |3 @    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- p- O* E+ j1 _0 z- U' Q* m
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) d1 l& ]+ O1 T' n+ B* |3 b8 C  set intersections roads with
1 O" `, l7 C" w# I) F    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
' C2 @: f. J/ {! Y3 X$ C, _    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' r) g) ]% U1 o4 R

& r1 d- _9 N; a1 C  ask roads [ set pcolor white ]
( A- D2 c2 {3 ^    setup-intersections
! @8 f. u3 C  X. @/ D* H+ L9 Cend4 A- x1 l4 X, E6 {9 H  n  U+ \
其中定义道路的句子,如下所示,是什么意思啊?
/ m: y6 |" D- I. ?# Y6 e set roads patches with
) P" L7 Z9 e: O0 Y' ?) ^7 W( h# Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( M" e% S; K4 [: N7 v/ Z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 v, @0 x3 p0 j% J* W9 |7 b( y
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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