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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 F1 ]! x' Q4 P! s  R
netlogo自带的social science--traffic grid这一例子当中,$ u3 N" T$ r( C1 Z1 J
globals! o6 O9 ]$ H. |+ q2 `$ u
[
! i- B- `' f) A/ s  grid-x-inc               ;; the amount of patches in between two roads in the x direction
$ }- Q# k7 Y3 g  grid-y-inc               ;; the amount of patches in between two roads in the y direction8 N1 R( G8 T9 |# h. b
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if% n1 n4 O: c4 W
                           ;; it is to accelerate or decelerate: _0 K) O; s- G: Q* Y( X
  phase                    ;; keeps track of the phase+ @8 B( S: r) O: V
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
! g* U( r, c: n# I  current-light            ;; the currently selected light1 |0 {# g( X5 l- V% O
/ N, i+ a: \0 n0 h$ J1 y. s
  ;; patch agentsets! n5 R3 m  o. z4 Q, o9 b/ L) E
  intersections ;; agentset containing the patches that are intersections
) r5 f$ _, F, L! i% [# u  roads         ;; agentset containing the patches that are roads
6 r9 U( e5 U  z- F0 S" g! t  R]
- {- y5 p& }% a$ K3 V" I1 O
1 n, V& a7 w+ D+ J2 O: v( lturtles-own+ |% {% l) q# `9 R
[
. {1 n3 N( Z# k/ N0 F  speed     ;; the speed of the turtle
# l0 v0 p2 F. Q  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
( K8 \; a0 m2 J+ Z, A3 f+ g/ m  wait-time ;; the amount of time since the last time a turtle has moved8 W& u3 n3 l- y0 g! V% q, b( t
]
4 M* x7 G( `! N: c
; J, q( |7 e  k. ^% O% opatches-own
' ~6 O( w. M" z: \' k0 T* S; h1 p4 \[1 z2 `& `2 W) C  v0 A# F
  intersection?   ;; true if the patch is at the intersection of two roads- f- r& E9 k8 v5 H6 ?$ m% `+ [
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
3 Y6 A% \# H' y3 U                  ;; false for a non-intersection patches.0 F; x# i& O1 q* L% D& _) [, l9 h/ `
  my-row          ;; the row of the intersection counting from the upper left corner of the, x5 f( |/ A- Z: d  M$ f3 W
                  ;; world.  -1 for non-intersection patches.. v; [, F" R; p4 R. V6 O0 f, l
  my-column       ;; the column of the intersection counting from the upper left corner of the$ P! `/ g4 J" K% }1 J& {
                  ;; world.  -1 for non-intersection patches.; c9 f2 I+ y2 C; Q
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
7 L% c' S2 _( T  auto?           ;; whether or not this intersection will switch automatically.
- ?8 j9 n1 q. i% `, p2 L                  ;; false for non-intersection patches.5 [1 k; r% u9 Y3 ?
]1 z' i* ]/ {9 r6 T

; Z7 K, o8 W  N: j
7 @& m) E2 Y3 m! v;;;;;;;;;;;;;;;;;;;;;;' d: U$ Y& Z# n! d! `7 h: S  Y5 H
;; Setup Procedures ;;
3 ]  |2 A! y' M) q! s& i9 b;;;;;;;;;;;;;;;;;;;;;;2 c6 ^' M( c9 K: X& J! w7 @3 v
( `1 E/ ~  c4 f) N3 z0 P3 _
;; Initialize the display by giving the global and patch variables initial values.
" V! d& a# x3 w& \8 G6 p3 p;; Create num-cars of turtles if there are enough road patches for one turtle to* e0 G: \% H! X( ]
;; be created per road patch. Set up the plots.1 t% b+ \8 `5 I5 P
to setup) E. `# f( J$ e* d% D$ w0 {# N
  ca! ^- c: x' E& [) j: ]* {( p9 e
  setup-globals$ l& _% H3 `8 ~& N0 q# ?
5 r- @" [/ H8 B5 I  B) I( B
  ;; First we ask the patches to draw themselves and set up a few variables
! `+ m) D; G! e  setup-patches
$ c/ a: l" i1 `6 ]6 i* \  N  make-current one-of intersections
! X5 k, O' S/ m! h5 R& j, T  label-current: m0 _" k* A/ s, h: F+ a
4 s8 f8 B0 v" D% C6 d
  set-default-shape turtles "car"
- `" y, e' W5 A2 O% t3 I
( X) m3 E9 Q/ r2 F* q1 Q. h0 b  if (num-cars > count roads)
, X9 t3 ]8 q: ~7 A8 Q- P  [
# r( H  J' n: H1 U9 m+ X) n    user-message (word "There are too many cars for the amount of "0 C; n7 z+ |, e0 N7 r0 d- c) P
                       "road.  Either increase the amount of roads "
0 [' I' }; p/ I- q% O; b                       "by increasing the GRID-SIZE-X or "
" r3 \1 ^5 J+ e; S                       "GRID-SIZE-Y sliders, or decrease the "1 o1 A9 r4 b+ E
                       "number of cars by lowering the NUMBER slider.\n"
0 n9 N4 Z0 A& k; Y3 n, s                       "The setup has stopped.")3 K/ v% u- e# n
    stop1 T: O0 B; q; o5 W+ h
  ]
  F# ]4 ?' ?* l3 U5 G3 b& h4 [& R1 G* E. M  P, U
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color$ U2 s' N; w( s, q$ G
  crt num-cars
: x$ g% f/ I! @8 F& [  v7 a  [
8 \5 u% I( M' ^8 A    setup-cars
) B6 P: P# i# L6 q, u5 X+ X# }9 F% g    set-car-color
  n5 E& q: \, A5 v7 @- a" m+ g    record-data
) b7 Z% y6 G3 D$ b) I6 D. v8 g- w' ~  ]2 D9 q' w: X* c. D
2 L# r& P* X% \/ W2 u6 [
  ;; give the turtles an initial speed
) Z# ~: e+ ?+ O  ]( b6 A8 }+ d5 R; ]  ask turtles [ set-car-speed ]1 c8 p& @0 d* C0 [( k4 u' ]3 Y
: S' C! Z4 ]# c$ T% j5 Y
  reset-ticks
% n* G7 b7 y1 {! {9 `. Eend
0 i; A7 ?7 q* ^2 s9 R( j" k9 p+ T  `( k! U8 @
;; Initialize the global variables to appropriate values# `& Q1 }2 L, D' X/ a* M1 C+ x
to setup-globals
5 k; m" v0 S8 n; F1 B  set current-light nobody ;; just for now, since there are no lights yet
/ }. d( Y  g; ]1 U2 m6 K  set phase 0( E2 e/ ^4 i* ^8 e. Z! v' ~2 ^6 C
  set num-cars-stopped 0
( ?8 ]) o& G, @  set grid-x-inc world-width / grid-size-x4 A! [$ e2 v+ @& [' K+ b7 M
  set grid-y-inc world-height / grid-size-y$ ~# n2 O8 i  t

8 p3 _. L% m+ a  e9 `1 |% ^  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary4 P3 x0 O- K7 Y+ o* ?, m2 `" e
  set acceleration 0.099" m; u/ q% f* J2 D3 B
end
; j" f* y0 [' ]( {1 Z
. c" D; h1 u  Q3 F6 a9 V3 c;; Make the patches have appropriate colors, set up the roads and intersections agentsets,! t+ h! t( X" Z1 T$ I
;; and initialize the traffic lights to one setting
9 F- R# P- V6 ?9 k. tto setup-patches
/ j4 }# i1 y/ d2 Y6 a, g( s! E  ;; initialize the patch-owned variables and color the patches to a base-color1 o5 R  z& g  a  K
  ask patches: \. f1 `" |- F' z; w' ^
  [" |" L0 k3 N; `- i0 I8 d
    set intersection? false
/ q* k4 j  K1 @) _/ B( [4 B    set auto? false) E5 |) w# ]- Q
    set green-light-up? true
3 a4 o: N* ]7 h) ]. A) x    set my-row -15 r) y9 V# \( q( u
    set my-column -17 J: O. z: e9 g* t6 B
    set my-phase -1
+ F6 d$ P) d' \# p4 A* h2 d* K    set pcolor brown + 3& |0 j8 r1 e, S% ~
  ]  h" r, T# G. A0 O( n. F. S

0 [9 h7 h% y; d  G! H: E2 J2 H9 `  ;; initialize the global variables that hold patch agentsets
9 n. f3 r! z& ?  set roads patches with
8 @) q; w3 Q$ ~3 c0 l    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: j& B/ J" `( L! ?; C0 B    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  ]' c* {3 {% d, ]
  set intersections roads with
4 b4 E0 Y9 w$ C& r    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
7 `/ h# ?8 F0 e    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' g5 c9 X; |, G, v

; c0 I. C0 A4 k- l" A+ m& r9 l  ask roads [ set pcolor white ]" D" d# _* z9 p. _6 s; ?
    setup-intersections. T# Z. y  H2 F! S; S$ E
end0 h7 z2 F: j+ D; G1 R& t
其中定义道路的句子,如下所示,是什么意思啊?9 k' d- I1 E# i+ T/ B
set roads patches with5 |' N' e+ I' [& X5 u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ j! X( e. S, s! `7 E& c  p
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ }2 _. z* ]3 M5 H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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