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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。$ S5 n+ z6 r7 _
netlogo自带的social science--traffic grid这一例子当中,
+ ]/ X; n. B. |  I# yglobals" [. p5 h. R' v, p& `7 S0 F! ^
[
# s- B% C) c& |0 ~& U  M  grid-x-inc               ;; the amount of patches in between two roads in the x direction
% q7 Z1 W3 K0 {9 n4 J  grid-y-inc               ;; the amount of patches in between two roads in the y direction
$ Z# l; r3 V1 i+ y  h' N/ N' Q- X  acceleration             ;; the constant that controls how much a car speeds up or slows down by if, O: W; p+ Y7 g- s% z
                           ;; it is to accelerate or decelerate% F5 B6 Z& p3 `, q0 e5 A
  phase                    ;; keeps track of the phase
1 t. {) N# v: m* x2 [3 p  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure. g1 x) H7 O  n& r' f% b  R
  current-light            ;; the currently selected light
0 W( t9 w0 r% T8 @/ U
/ S/ Q4 b: H' V, q( ]1 P  ;; patch agentsets! a# A2 _% `9 ?9 a
  intersections ;; agentset containing the patches that are intersections
1 X" F2 w2 W7 z0 a* u  roads         ;; agentset containing the patches that are roads
0 a* S% s5 w9 I% D]" H  |" f5 c) e1 V( N2 o5 W8 {

& C# e5 a! T8 m2 Tturtles-own
. z" T; y1 [5 Y3 Z1 _, B[& i6 p- K# O' Y1 n- o2 N' `
  speed     ;; the speed of the turtle
9 f1 l( `( v; ^6 O$ L* K  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
! h& x: V% T! f: u  wait-time ;; the amount of time since the last time a turtle has moved
6 Q9 f5 i* }+ Y9 k, b) e]
" E$ m& o/ Y+ o2 Z3 n; L. G1 [0 A1 K4 g
patches-own
! ?% U" N+ C& y3 }5 k[
5 i( {5 B/ E% a6 j* m  intersection?   ;; true if the patch is at the intersection of two roads) u- n1 e5 S7 y: h
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% A' F( y6 ?* c                  ;; false for a non-intersection patches.( m% w* a+ W& o& m# r0 f6 |6 m
  my-row          ;; the row of the intersection counting from the upper left corner of the, S5 w' _- ?" t
                  ;; world.  -1 for non-intersection patches.3 e5 U$ z0 X6 U' N; x0 H/ V
  my-column       ;; the column of the intersection counting from the upper left corner of the4 d9 C: Q# X( S1 W# R8 z$ C* ?
                  ;; world.  -1 for non-intersection patches.8 r6 S0 _' ?/ a
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
6 x" H( M0 @  X% _9 Q  auto?           ;; whether or not this intersection will switch automatically.6 B  T' i. c6 x" K
                  ;; false for non-intersection patches./ w7 I, k% S( R( V# [# q3 ?
]/ R. @1 V0 [: Q

$ v: \* P2 u7 ~* J3 Z/ A6 w3 ^, t4 ~; B- ~. \$ F' p# l" ?
;;;;;;;;;;;;;;;;;;;;;;
) k2 A! `) ^7 Q% P8 t% p/ U8 U5 _;; Setup Procedures ;;
! }8 O4 W7 j" w" N$ ];;;;;;;;;;;;;;;;;;;;;;
  {6 y" t# }4 u/ |* \) T& Q  u0 |
;; Initialize the display by giving the global and patch variables initial values.
" }) n* i7 l/ L* m7 W;; Create num-cars of turtles if there are enough road patches for one turtle to' V9 l* F1 ~& {# j8 f: f% V5 _
;; be created per road patch. Set up the plots.
/ f( E8 F9 O: W. @1 K7 s; s. E! l! S+ @) gto setup9 F$ c# U# i$ t1 o/ D6 c8 X
  ca6 e$ _! L1 |8 z$ N/ X9 F
  setup-globals5 B4 T! d; d6 w: V) J4 L2 v
+ V+ @- l$ Y/ ^) F
  ;; First we ask the patches to draw themselves and set up a few variables1 Q* |+ \& z9 W0 V  |
  setup-patches3 m0 `$ u- B) e" d$ e8 v: p! Q
  make-current one-of intersections
; a5 G5 ~5 G& ~6 T  label-current
6 J# P) ^5 q" ]8 k
; i) B+ r+ f8 @7 s$ @9 Y  set-default-shape turtles "car"
8 ~/ d! S- ^6 K1 X7 {% E* j
0 |- `2 u- g1 @5 Y  if (num-cars > count roads)
2 |. w' n$ a6 J2 x' y  [
: K1 v0 Q; \% {& \    user-message (word "There are too many cars for the amount of ": Z6 k* P4 Q- U4 D7 P& X( m& h( @+ b
                       "road.  Either increase the amount of roads ": X6 r0 h7 p# L3 Q6 H
                       "by increasing the GRID-SIZE-X or "$ }  p. U- x" O7 L( X# j
                       "GRID-SIZE-Y sliders, or decrease the "
9 j# h( T4 n/ j: u* N$ Y" F6 b                       "number of cars by lowering the NUMBER slider.\n"
) q: ^8 }& t( H7 |! h                       "The setup has stopped.")
7 ^% v' m. j6 [7 F6 @2 R  y3 K    stop1 m. I) H0 U9 G& o3 z
  ]
- I, b3 a* C! O- X2 f0 e5 f7 v; @) _9 I% {6 m* q% c7 G
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color& y0 [2 B7 R" F1 A3 r3 L/ @9 Z
  crt num-cars
  Q3 G1 g) T  m4 T  [% w" k/ I4 c$ N2 e0 j) _5 j6 P5 k
    setup-cars, Z' G! ~5 [& k0 O6 B
    set-car-color
! v% z) |8 `" ]. h  f2 ]) A    record-data& e7 K  g/ X: N- r- h
  ]0 m0 f1 X9 z. j; u8 y- @/ E

; B& _- |: e# c8 t3 M  ;; give the turtles an initial speed
4 p, s/ ?0 {1 r+ S# b! T7 m9 P  ask turtles [ set-car-speed ]/ A* q) t3 g: @" C

! J) F) J$ Q% D2 C) x2 L4 ^/ T- Z' w  reset-ticks* \" m: d7 L& D/ H- x6 _/ h
end% s* \! g9 @! F) B. _+ b  x3 `" W
  O2 s! o. h, @, X9 h" |+ O# w* I0 t  c
;; Initialize the global variables to appropriate values
4 j# E- `& B! J- k/ s+ g9 s5 ~to setup-globals+ Z* f( \$ x7 |* F! [
  set current-light nobody ;; just for now, since there are no lights yet
( ^+ h6 m# B# z8 l- ^2 N( E$ Y( c  set phase 0
! n/ M9 H4 T. ]6 T& {: |  set num-cars-stopped 07 E) F8 i5 b8 O/ T
  set grid-x-inc world-width / grid-size-x
7 E1 A/ b6 d5 y  set grid-y-inc world-height / grid-size-y
1 d! z# y0 j1 K4 i
6 L% ^/ A. K1 M1 ~5 ^0 y9 J  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary) d: a5 q+ h8 \1 X& D8 ^
  set acceleration 0.099
$ W2 _' T* t/ T8 ]7 c& V- lend+ ?1 R/ b5 g5 j( L* I  Q/ b: x( o

7 t! D, d. _. M  I5 Y+ m% C1 n;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
5 {1 S5 I6 w3 D" y8 u, j5 v4 q;; and initialize the traffic lights to one setting5 u; i+ i- |$ Q0 y- `/ K. d, ~, H7 G
to setup-patches) x5 [7 a- ~4 ~# U; t' K1 b
  ;; initialize the patch-owned variables and color the patches to a base-color
; C  r/ o6 y1 ?% L  ask patches
3 S1 m. d! d# F: r  [
# {7 \4 k4 D) o    set intersection? false
8 `% _# Z3 }5 Y( l' P4 t8 n! P    set auto? false
5 d* W6 D: @6 B    set green-light-up? true
& y6 g# c# M+ z6 X4 ?3 L% M    set my-row -1
* k7 c* X. _& Q4 o2 ^7 {2 {; t    set my-column -1( v. [- l6 ~& ?! p# q
    set my-phase -1
4 }& y  S- i; W4 V    set pcolor brown + 3
( c* s0 P8 l" t( r  R2 ]) O  ]
' {, r3 J. T& l6 F2 \5 ~" a
4 g& A, U/ Q" ^9 b! q9 u  ;; initialize the global variables that hold patch agentsets. t1 B2 c4 ^8 O5 U3 K2 v! @) V
  set roads patches with
5 H# [/ w  q8 Q% z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 \6 K% N. r0 {4 R& w) d) |4 n5 |
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( Y$ g+ n, x: m4 O' g! S0 M
  set intersections roads with
* A9 a8 g# x9 M- ~1 E    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
' l( _! Q! L9 @; c    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 q* k" {2 v" h: p2 O! Z
: m$ j( U( X5 N
  ask roads [ set pcolor white ]* g! R& I9 e$ L
    setup-intersections
: {, x6 |' y8 |" H5 kend
  }5 U& `& h6 l/ [" Y9 ^5 B7 F1 u其中定义道路的句子,如下所示,是什么意思啊?
2 E# }9 d7 o# S$ v6 Q( i set roads patches with8 M+ x" I$ p7 _% y5 _
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) ^0 [! c7 @& H7 g0 x0 D' r6 O    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ S) M8 _# F: w! I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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