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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。
/ i' J" E- W" @netlogo自带的social science--traffic grid这一例子当中,
+ j+ D  F# }6 u/ ]9 w* s! qglobals
5 i# }, X' h0 u- s5 L[
" K0 Z( o8 `! \. T  grid-x-inc               ;; the amount of patches in between two roads in the x direction
- ~4 l1 d- E! h+ s* i7 m& K  grid-y-inc               ;; the amount of patches in between two roads in the y direction* R% H' Q7 y; C; l' P+ n
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if: l+ {, V6 o& U: \# H+ ~. x
                           ;; it is to accelerate or decelerate$ X& F. S6 C0 }/ o+ I" K
  phase                    ;; keeps track of the phase
+ y1 f- E; V- u  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure6 G, [4 ~$ l0 D* }
  current-light            ;; the currently selected light$ Z( j2 B! d" J! V
: w0 x1 O2 {: }1 w
  ;; patch agentsets
# b4 Z. z8 Q8 I/ s% }, Y  intersections ;; agentset containing the patches that are intersections
$ W, [% _0 W  ?( A! _6 e  roads         ;; agentset containing the patches that are roads. P# T& C* q% E
]
: h) L8 h3 |! T! Z; T- N# ^
0 }2 O- k/ Q" s* K' oturtles-own* R, V4 C, \4 B. ]; x' r, \* X
[
' m, f. E( v+ Z, B% {  speed     ;; the speed of the turtle
) ]2 b) I% Y3 [; w  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
5 L* b' c3 p3 g$ N/ r7 C  |9 l  wait-time ;; the amount of time since the last time a turtle has moved
+ w1 @7 @* @$ B  d! q0 D]
" i7 Y9 M/ V/ P' Q* ]; x( o" F' Q. ^1 P* p: t
patches-own2 C0 G" a* a& H  y% E* x+ E- o# D
[& B1 B4 x2 W3 g! t& G/ U
  intersection?   ;; true if the patch is at the intersection of two roads
! i4 Z! h4 S. w4 h  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
3 i% d, t5 `% Z  @; M, Z1 v* h                  ;; false for a non-intersection patches.+ y/ {; i# m' R
  my-row          ;; the row of the intersection counting from the upper left corner of the
( ^7 w; ?) C" W3 a) `$ D! g2 q0 C( p                  ;; world.  -1 for non-intersection patches.' g- t$ E" J2 l" g
  my-column       ;; the column of the intersection counting from the upper left corner of the* [% c; Q' o: C- C
                  ;; world.  -1 for non-intersection patches.
: h/ V( C( j. }" ^  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
# I+ C& }5 Z: {2 D  auto?           ;; whether or not this intersection will switch automatically.* T# C: q( \* \
                  ;; false for non-intersection patches.+ s/ ], B! k6 Q
]
( j- u6 g4 R1 g
+ _+ O+ `& {8 Q. X* I% D' G! ?7 N4 U0 o' g1 P3 }1 |; w
;;;;;;;;;;;;;;;;;;;;;;$ b9 d' g& R: w  R2 b
;; Setup Procedures ;;
4 f- y$ F* B* D4 y+ {7 ^  j- p;;;;;;;;;;;;;;;;;;;;;;
( z5 C& U( \, e8 b
9 c: V9 f0 S: A: l;; Initialize the display by giving the global and patch variables initial values.& w+ L+ l# u7 w  y  U# Q+ |0 i
;; Create num-cars of turtles if there are enough road patches for one turtle to
2 S8 N1 V* n9 B; t;; be created per road patch. Set up the plots.
" r" [8 c8 w3 d/ h1 h- ~to setup
' b, v. v8 `, ~/ \- T0 S. C2 `  ca
! t( I% E* b% C- ]  T  setup-globals
+ D: R: B2 W& U3 q8 M6 B8 L4 M5 D7 U4 Y& K6 T) J9 ?1 p
  ;; First we ask the patches to draw themselves and set up a few variables
; F4 B  B) w" V1 I8 \9 G& a  setup-patches4 \0 D3 Y( X; S- e
  make-current one-of intersections+ U1 _5 l0 U7 {5 Y) F# o: ?
  label-current/ G1 W" q; [, C( ^0 Q; u
5 Y7 ?( H) H% W( _1 K
  set-default-shape turtles "car"$ R1 m! `; q. x

1 _8 T6 w9 l3 E& k# m  if (num-cars > count roads)
: ^( ?! k8 q, j, |& {9 S  [
! R: v- {6 v' ]+ j    user-message (word "There are too many cars for the amount of "
: F# I# M, e$ J6 I) G% C! k) F                       "road.  Either increase the amount of roads "  |' N# ^5 F1 `; c! f( e+ y; T
                       "by increasing the GRID-SIZE-X or "; e+ E) P+ K, Z; R' t% h
                       "GRID-SIZE-Y sliders, or decrease the "
7 r: ]: g6 r& [  B4 x9 J( W6 P                       "number of cars by lowering the NUMBER slider.\n"1 E  S$ A/ n" n6 X$ d, r7 c
                       "The setup has stopped.")
+ r, a8 i3 W' t$ f3 f  V% M    stop
7 f6 P+ g3 }: k3 H  ]
7 C% _$ G8 P) d( N. T  }6 I- E5 X- _: n) F- b1 K: V1 k4 m
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
' q/ ^0 h1 m/ e  i9 E' D8 C; t  crt num-cars
$ ]: `/ d: p& o/ B9 j" @% P  [
) s' I( G" b( ~+ ?: e# v" X    setup-cars
( V. B) E2 `2 Y    set-car-color
. ?  b; K2 W) `) b7 H) v    record-data
! V1 i3 o& P1 ^; w0 ?7 r. X" P1 U7 n; o  ]8 F" M& r: R# A% j

$ e" a  m" k4 v5 h) k  Q, {  ;; give the turtles an initial speed
6 i5 H) ~3 x) _. U9 c6 s' x  ask turtles [ set-car-speed ]
- p( H3 i+ J& r( ?$ V% P1 u& c- }% l7 g6 H+ }$ }' [( h
  reset-ticks" F) z6 d* w* [7 O: C
end
6 l- N0 Z4 P1 F; k1 @8 p! b5 D9 H) e0 l: M  g
;; Initialize the global variables to appropriate values# A% V, F( e- h4 @
to setup-globals: r; l/ }& J, }, [
  set current-light nobody ;; just for now, since there are no lights yet
7 J  X/ Z% ]5 \  set phase 0
( T6 d1 s' O. h! G3 ~: `  set num-cars-stopped 0
1 M! [/ ?3 h  ]; P* r8 l  set grid-x-inc world-width / grid-size-x
+ S7 R/ l9 }! {4 {* Y8 {) d  set grid-y-inc world-height / grid-size-y7 f1 Z3 F2 R; v6 D+ d4 q& R4 r; |

: A9 o! J/ t, K  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
! x9 w" `1 v4 p! a3 v) |  set acceleration 0.099
  b6 Z4 l$ r% J- Z1 [end
8 {" F1 ~8 U. D. ]' ^+ \8 m! U
* T0 k2 m6 ~; _- T, W, m% _;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# _6 o1 m% g3 w" N6 q;; and initialize the traffic lights to one setting7 }2 U/ P0 E: F1 h: `6 O% z
to setup-patches8 M( F! v; A5 D7 ^
  ;; initialize the patch-owned variables and color the patches to a base-color, R' v/ X( |1 Y, j, \
  ask patches" f* t1 [; g6 }$ ^/ U" P! {( r
  [
/ J, K; s% K/ {' y6 ~/ P/ L    set intersection? false
9 u! @$ }9 X" K2 L# h  g6 u3 Z. y3 j4 Q    set auto? false  i$ Z; U2 u7 E, ^* [- z; s
    set green-light-up? true
8 g6 a( Y& E: b) X7 c    set my-row -1+ u; n8 y4 A& _; F' \" I. u7 a
    set my-column -1
& {+ f0 |6 |+ z1 g4 m2 A    set my-phase -1! Y. Z4 ?- R7 S& A
    set pcolor brown + 3
* y" ^0 u: N7 x; R  ]2 ]0 Q7 y- H8 g/ J

* s& \1 X8 r2 |  V5 C0 L  B  ;; initialize the global variables that hold patch agentsets. t! B/ _7 J  a: Q& r- i: C: S
  set roads patches with9 p. w9 c  x! N6 ^
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 R& \; B. y( ]; m, }8 [* e) v! k
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" G  A+ |9 k- D; W. {  set intersections roads with1 ~9 X5 J8 [6 e5 p, e8 \
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and+ a# C5 u- ], n8 G- H) a
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 \7 W. K( [! j/ @" A! K
- E9 _% y6 e# E3 w  Y" ?
  ask roads [ set pcolor white ]
5 B/ H7 o1 o; {* [6 p: V) \9 |) J    setup-intersections. T6 H- _. N+ {8 t. A9 D2 L# e
end
  {, v; K) X$ H. l/ E$ ]其中定义道路的句子,如下所示,是什么意思啊?" D& l( t  \  N' ]; H& E" L
set roads patches with
; Z! q' n6 f# [2 p2 @7 b1 E    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or0 [7 Z' d1 l7 p0 M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% k" X% O- o3 R* N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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