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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。' c3 N1 y/ q$ F7 B" n# |/ g
netlogo自带的social science--traffic grid这一例子当中,
- m; k# D: n! O1 T4 O$ H; I  Dglobals5 K% X1 G' W) f
[9 p, r# A' \# _. }9 }; D
  grid-x-inc               ;; the amount of patches in between two roads in the x direction; ^1 `2 [" u3 h$ y5 q! a( ^- u
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
* z. t, p$ y" M' A4 I9 ^* b  acceleration             ;; the constant that controls how much a car speeds up or slows down by if% f) l" Y" ?/ f. R* T# q
                           ;; it is to accelerate or decelerate
! ?+ {& d$ T  X. `( u  phase                    ;; keeps track of the phase
: j; N( L) V/ J4 v. M7 V9 X9 R  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure* d/ |* c! L/ X/ N, a
  current-light            ;; the currently selected light
$ G6 ]. }2 E' Q% w( i& W7 F8 }) t
' e9 B4 q0 A/ V8 Q) l  ;; patch agentsets9 M6 u( p- ]6 M) Y
  intersections ;; agentset containing the patches that are intersections
1 N( a, M* E/ |( i( `; X4 ]: h  roads         ;; agentset containing the patches that are roads
- D( K  {1 j. o% ^& m+ r]
8 ]* l7 x) o$ ]6 X- K( ]* f! G
* e8 c" Y3 }& Gturtles-own5 {2 {5 j( d. h6 }" h4 P3 Q; r
[; d- o7 C+ `" g  V! d
  speed     ;; the speed of the turtle3 ^" X* `6 W* r3 Y+ L# ]
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
" k7 m9 D" O1 g5 k0 K. j  wait-time ;; the amount of time since the last time a turtle has moved
0 G9 e& [' v& ?2 l]6 R& P) `3 ^( e' ^

: |: z2 s3 ?! \: F; n" q+ L$ o& Apatches-own# S4 w! w6 p% X  ?4 u
[) _* @  V7 G' |. P+ l/ e. p$ a  ~$ @; Q5 u
  intersection?   ;; true if the patch is at the intersection of two roads
5 `7 ]$ L, e- q1 W$ s  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.  z1 G  w( y# a0 I! U! W
                  ;; false for a non-intersection patches.- W, ]# I! G+ _. L
  my-row          ;; the row of the intersection counting from the upper left corner of the) @( ~4 c' U$ [9 S1 W
                  ;; world.  -1 for non-intersection patches.: e* X7 n* g2 c9 [; _
  my-column       ;; the column of the intersection counting from the upper left corner of the  R/ O6 y9 x0 R. P
                  ;; world.  -1 for non-intersection patches.. i8 M& f: R5 ^: \4 l/ d& v4 F& {
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
0 x  n& g+ y! m0 H9 ?4 Z: Q  auto?           ;; whether or not this intersection will switch automatically.! d" {/ L9 @7 I/ @, r2 C' J
                  ;; false for non-intersection patches.
7 n6 v$ f: i* v]
) A$ d  a; v, T2 f% i4 e& W  F' G4 Y) ]. A2 _2 B
. p, d3 u; q+ k; S9 {
;;;;;;;;;;;;;;;;;;;;;;: I! a4 Q/ B6 S7 V9 q
;; Setup Procedures ;;
# O7 w( [' A: q  a$ y+ y2 U;;;;;;;;;;;;;;;;;;;;;;
6 [4 c7 n) b! b1 v- e" R. n: Z( B' x/ y
;; Initialize the display by giving the global and patch variables initial values., E3 Z& c1 ^' `
;; Create num-cars of turtles if there are enough road patches for one turtle to* G2 t8 o. @9 q2 f; l
;; be created per road patch. Set up the plots.# D4 {- h& ~" C3 t# ^' p
to setup
8 L3 i! Q4 v5 ~( e3 |  ca. ]" x# x1 `* J4 s
  setup-globals6 G# }% h# x( I, ?# [% c

- b( D& v1 j9 y3 C  ;; First we ask the patches to draw themselves and set up a few variables
+ p( L9 G. G& e( z) R; N  K  setup-patches
6 l7 z5 \; L8 p: K, \  make-current one-of intersections% v% q* Q# \5 C* V% a2 X3 i
  label-current6 M5 p: H( V) \9 K/ I# o/ ?7 o

; m2 k2 z! ~: O" c  set-default-shape turtles "car"
6 J0 q9 k6 a6 d$ Y/ z, k
4 \' M8 m5 S7 N6 O0 z  if (num-cars > count roads)* M) w9 u, i! y1 u2 u
  [
$ Y- D8 a+ {) I) R2 A    user-message (word "There are too many cars for the amount of "
- F) ~9 Q0 l. t# Q0 s$ l* ~                       "road.  Either increase the amount of roads "
+ d* @- O5 ]3 |$ _& v                       "by increasing the GRID-SIZE-X or "
, o7 H4 g8 _/ @7 B% u8 d. d' a                       "GRID-SIZE-Y sliders, or decrease the "+ x% h5 j# m* }1 R
                       "number of cars by lowering the NUMBER slider.\n"
$ W* L( z4 m3 ]% d1 h- ^                       "The setup has stopped."): K, z# _2 N6 g+ x# x$ x
    stop
* D! i4 p+ `& n$ H, f" o  ]
( l1 G& @7 F7 N) n% a- Q2 n" [0 |8 ~
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color" b% k# g) @+ w& M
  crt num-cars7 A4 ~$ Y) E/ X& e( b5 ]$ n
  [
; F* _# S' F7 \9 L    setup-cars
8 N6 J) P' V; e) _& U  U$ a  w5 G    set-car-color
& z  Y' B' D. w. F    record-data
/ y- @& d; b' z2 x: @) n  ]" \* \( W( n- C) p
, j( a7 H* \7 D2 R
  ;; give the turtles an initial speed$ U3 R! T2 \3 e+ x1 f$ }
  ask turtles [ set-car-speed ]  Z6 s  V2 e' ~- _- y) h: x3 b

7 R( B$ E3 `8 _. W% _+ P+ f  reset-ticks5 q3 Q% }( X# V& a6 @+ z0 @5 [
end6 y8 \% d  y8 q  D

" |% ~/ z) m0 j( t;; Initialize the global variables to appropriate values
' J% K' v5 i* j& b- c' ]0 s! ?+ yto setup-globals
0 J! C. Y; W3 {: S  set current-light nobody ;; just for now, since there are no lights yet3 s$ Z* m4 @  D" T% V
  set phase 0; m; V2 @6 z6 H$ U' w$ W0 D5 k, ~! d
  set num-cars-stopped 0$ r7 P" G- z0 \( v* h5 L7 V
  set grid-x-inc world-width / grid-size-x
4 h5 _! Y. Q  O/ i  set grid-y-inc world-height / grid-size-y
  z) y6 p% w& a7 O! x0 ~, e2 M
' l' b. e/ f% {; ~/ s+ o  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
; k! {6 X. S+ d- R0 b; W  set acceleration 0.0993 v6 V- \* q! M2 [
end7 B7 J$ f" R0 H$ g

) j- M) P9 a) Q+ d4 f. T;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
1 `& ?8 H' R$ v4 D3 J" U* o;; and initialize the traffic lights to one setting
$ h, N9 T( f1 J. Fto setup-patches& U2 @  {/ ]( b9 ~
  ;; initialize the patch-owned variables and color the patches to a base-color
" p0 f$ {9 z/ Z$ _& H  ask patches) }9 [5 H5 y- R( j$ i  [2 v3 @% d. V
  [
% }8 _! u2 t3 d    set intersection? false
7 Z! Y$ N2 _& \7 P9 F    set auto? false
7 A* D* e  M! J4 Y2 \    set green-light-up? true
- N7 z  Y+ G" \$ ?" R    set my-row -1% e2 E, m- u* q# V- }( c
    set my-column -1
3 s0 f/ A" U, V4 W    set my-phase -1/ B% B' k( b) m, B  z8 T
    set pcolor brown + 3
+ G( V5 q4 R, _6 B  ]
9 H' D5 v% p' a' E$ i0 m3 {! i* e% A7 L6 l" R
  ;; initialize the global variables that hold patch agentsets+ y: O  ?6 A- }" W! O/ J$ S
  set roads patches with4 U0 S8 D: y  V" W1 q% a" @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! }$ ~, K* ~. @6 S3 j7 C    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 `& n7 P$ V* g$ q0 N  set intersections roads with( E, H0 L1 D. [7 b1 u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and7 c& @4 s6 v# p
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ I& H4 S- K" B. y0 v4 r: \

  I. p# Y# I$ R1 \$ v! ^  ask roads [ set pcolor white ]# w0 o8 n3 Z' ]- m9 e
    setup-intersections
% o1 ?8 a8 A! x/ f$ J7 Yend& H8 J- d- D4 D
其中定义道路的句子,如下所示,是什么意思啊?
9 S3 V3 s( ~* F set roads patches with' ~; N/ F3 Q. s" w7 \
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or7 B# f# l# U" N2 @$ Y! u
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, f' Z/ F& f# K( d: g) v& {3 e3 L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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