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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。
; @$ X8 `  F' W0 @# ?8 `0 Z+ Q1 r0 Anetlogo自带的social science--traffic grid这一例子当中,
; k8 [* t, ^3 V) n3 \globals
/ `5 m3 u2 s9 J# a7 R" E2 b[
5 ~# Z4 p  y, k/ M  grid-x-inc               ;; the amount of patches in between two roads in the x direction) {3 z& i3 h4 D2 M/ C- e/ W1 D3 h/ e
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
& Q& K# Y: L$ h, ~5 {  acceleration             ;; the constant that controls how much a car speeds up or slows down by if3 a; R" O( T- {1 ]& j
                           ;; it is to accelerate or decelerate  G* U, I$ b% N9 n; c
  phase                    ;; keeps track of the phase; d* ~# C: h$ |' i1 e9 u' Q: v
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
4 H; e. o4 F' g0 `. Z  @* w  current-light            ;; the currently selected light2 A- O) m- _9 n. _

+ m0 m3 S9 j$ X9 f4 m1 Q  ;; patch agentsets
7 Z& I- S+ T$ z% b6 b  intersections ;; agentset containing the patches that are intersections
4 R, ^7 g/ |: G7 [  roads         ;; agentset containing the patches that are roads
! l1 k9 q) D0 Z, f( i, Y% R2 S1 }& m]5 i* p# T! C% B8 u

5 _* w6 N! s3 s* X# Kturtles-own# Y$ d2 U" h& `" G
[
) |9 X8 d; E" o7 T: l  m  speed     ;; the speed of the turtle# J+ u* Z* A# P
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right& z& G% s$ G1 F+ \/ |( o9 l
  wait-time ;; the amount of time since the last time a turtle has moved
! T/ I0 v$ q: J5 |]
8 ~! e* K( X6 v. b7 ^* c5 _, b  D) L9 B
patches-own
! F+ _- G6 a, E  [& o# b[
8 N4 |/ v& E3 U) |  intersection?   ;; true if the patch is at the intersection of two roads2 [7 R; ?7 T0 P# P( \# V
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.0 a6 r( Z+ O# F$ L
                  ;; false for a non-intersection patches.
7 n: o' D% o; N0 J  my-row          ;; the row of the intersection counting from the upper left corner of the8 T, a( x% X# R5 R* l8 p
                  ;; world.  -1 for non-intersection patches.
# C" Q* z" O, }1 v2 U" t7 J9 E3 n( t  my-column       ;; the column of the intersection counting from the upper left corner of the2 Y* q. U& W9 S0 G. W/ C6 i- e5 I
                  ;; world.  -1 for non-intersection patches.# b3 [7 e. [$ M* R% _& L
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
; k' @* j: O' y  auto?           ;; whether or not this intersection will switch automatically.
6 @# @. w0 I( V+ V9 E8 P+ _                  ;; false for non-intersection patches.
/ F# B+ d* L+ W5 L]
' d, S- {* G* c$ r/ @! }. h
- J2 ]7 }+ {  R+ a; K, C9 \  B5 y: _# e& Q7 d/ a( ^
;;;;;;;;;;;;;;;;;;;;;;( B4 l1 P6 x& u0 u& e. [
;; Setup Procedures ;;4 m4 {4 |' H) _0 N2 x8 O8 U
;;;;;;;;;;;;;;;;;;;;;;+ a( @( E: [8 K% y6 U

6 e( H* D$ @3 r4 @7 O;; Initialize the display by giving the global and patch variables initial values.
* q7 F# {; G' G0 |; q" h;; Create num-cars of turtles if there are enough road patches for one turtle to  [  @+ k  w2 f; M) I! \/ Z1 b
;; be created per road patch. Set up the plots.
' _! z! X3 j- Z1 J" p9 o% fto setup
* i7 G% E: I+ }& A" D  q2 C1 {  ca
. k5 v, o( K3 d# Y4 ^: F# a  setup-globals
$ t/ i9 o3 ?4 W' B3 c: `/ ]/ A6 b* O, \  J
  ;; First we ask the patches to draw themselves and set up a few variables6 Q  q" T0 T. Z$ Y, l) v. `
  setup-patches
6 A" M  ]5 w1 N/ G  make-current one-of intersections" G$ P0 o# l5 D0 z; i  z. z
  label-current
- @2 W, q9 S, a4 y' l1 j( I* W8 Z
1 [( b# v; z& c0 C; M& I  set-default-shape turtles "car"+ X" ~3 U: \( F/ e' o, ?# |
4 W' V' `) O, _& S  A9 b
  if (num-cars > count roads)
. e- L7 K  g& ?  [7 N2 m# P2 b& w3 X* W# q2 D3 o2 s
    user-message (word "There are too many cars for the amount of "
, Z( L- ^) G! e! n+ H                       "road.  Either increase the amount of roads "$ V7 \& @7 [/ T3 l0 N! J
                       "by increasing the GRID-SIZE-X or "6 {7 G. E& x+ V
                       "GRID-SIZE-Y sliders, or decrease the "
. }9 {; \; d, S& B6 U' T" U1 @                       "number of cars by lowering the NUMBER slider.\n". R) u4 i( B1 _+ Z
                       "The setup has stopped.")" O$ [, d( q- G5 |; i1 Y* `' q
    stop
! S2 e0 w/ A- B, q  C/ b* \  ]
0 {' p' P( I2 ^; `
! P6 p. Q3 ?" u0 J2 o* K6 h  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
/ {1 K6 b* R) g- a  crt num-cars. \( B6 Y$ h& \* c4 v
  [
7 V0 j6 E7 O5 a8 h& d* [    setup-cars4 s. w* K# a. _$ Y
    set-car-color
6 ?4 K1 c) o: ~4 a; G( a    record-data# D+ U: e+ L9 U. K
  ]. A; D' }5 ^' k0 z( Q

5 o, _) ~% Z; m9 X, O" l  ;; give the turtles an initial speed5 z3 i3 k( q6 Q9 g/ H( O2 @! m
  ask turtles [ set-car-speed ]8 E8 w6 o" B5 L1 G
6 ?. j1 l  w0 Z  S8 Z. y
  reset-ticks
( q) R% B! a3 Q0 d4 kend+ ^+ R# j% i- h+ B" k; h! N1 U8 F+ P3 f; T

- m& P  l) o$ D& m;; Initialize the global variables to appropriate values0 w8 I/ g( D% K3 X. N) q- L
to setup-globals  u% B9 i" k2 U2 m
  set current-light nobody ;; just for now, since there are no lights yet
1 ~. H8 q+ h- y  set phase 0
# g8 t5 [0 \9 T: V  d4 C$ F  set num-cars-stopped 0
, r) J- T4 ], J- A* _" t  set grid-x-inc world-width / grid-size-x
4 u* g/ I& [( v' Z  set grid-y-inc world-height / grid-size-y
+ w/ p6 h9 `6 y$ }7 h) o# R& @8 j5 M  W) b6 {
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
0 C- i4 b, e7 Q* e) }! z/ H  set acceleration 0.099
+ i3 l/ g. U" ~2 L/ M# p: K1 u5 eend. |, E. e) r; T; z8 f

) @! X1 x4 m$ P% ~& l+ ];; Make the patches have appropriate colors, set up the roads and intersections agentsets," }. l* p7 e# d3 V1 z( g. Q
;; and initialize the traffic lights to one setting
  g% @& x( V7 ]7 n( [! Vto setup-patches+ u1 D! n/ Q, T- ?
  ;; initialize the patch-owned variables and color the patches to a base-color
! z9 ?6 q- g  f$ g2 n8 ]/ D( o  q  ask patches
/ v5 p" ?: `0 H9 o5 d5 u  [
* D3 M0 v/ r$ }; n8 E    set intersection? false
. h0 R; `% p% G2 H5 h( O8 Y    set auto? false
2 |6 d2 V. }4 U3 p) a    set green-light-up? true
) @/ ]& K% J( g# H, W4 x    set my-row -1
8 ~0 E6 W; c7 k& j8 T) A* |) Z( G    set my-column -1; F) t8 c8 d2 s9 X/ S. O: D# k. D& o% B
    set my-phase -17 m9 y4 _$ [5 Z# B: o3 B
    set pcolor brown + 3
5 {: I/ _0 W, g- p# a/ h# Y4 O  ]
" G; q* y# [4 }( a5 {& e5 ?
. E& P. o" Y& G" _8 H  ;; initialize the global variables that hold patch agentsets* U$ q! f- G$ h% j# S
  set roads patches with" ~, j3 \  U( {
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 X2 D4 W  h) f# s/ Q7 X9 t7 V    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 v% m' L: s$ L. ]( W$ X: P6 Y
  set intersections roads with# K! h, g% x$ S- a2 ~8 O6 Y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
* S9 R6 e' d1 v$ j: ~& K' t, K    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' a" q9 N- P  }& X, ?/ [

* }! J! T) n2 X4 i9 G  ask roads [ set pcolor white ]" D/ N7 u6 G% Q" c
    setup-intersections; w4 l% V$ T  C* k. E' z) z) G
end
9 E4 K2 t: E; M# H5 Y, n其中定义道路的句子,如下所示,是什么意思啊?8 v* v2 c. F; Y* Y1 V) r$ m  D7 h8 a
set roads patches with( [+ |# k8 g7 Y9 U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 }: W* \# k# h; f    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& g* @0 v* Y% g
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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