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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。9 ~5 d4 h) ]  D4 {
netlogo自带的social science--traffic grid这一例子当中,6 ?& d4 x4 U& m" H  w! Y3 i' U3 n
globals
- t% p8 G" T8 ^+ x- w[
" l: ~' o8 x& M! o- W3 ~  grid-x-inc               ;; the amount of patches in between two roads in the x direction
( |# Q- H3 A$ [  U+ F  grid-y-inc               ;; the amount of patches in between two roads in the y direction
9 u# |$ d* j5 E* P4 S  acceleration             ;; the constant that controls how much a car speeds up or slows down by if- l" g  h2 l3 X, l3 ?8 j
                           ;; it is to accelerate or decelerate, E; H' L9 ?- y/ ]% |  ]
  phase                    ;; keeps track of the phase+ [6 z' ]0 H& Z$ d) Z  q  d8 P
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure3 X" J  P0 R' x' j0 e, \, O
  current-light            ;; the currently selected light9 i; q, x# X$ J0 o% [
0 h6 ~$ ^. ^% {' u8 b
  ;; patch agentsets
! f$ W4 q) C- l2 k, B. d' K  intersections ;; agentset containing the patches that are intersections1 h1 W7 f' y3 G' |, ]1 B# ?
  roads         ;; agentset containing the patches that are roads
( N( E1 Q' r, a1 B5 E7 l9 m]; P2 h6 W2 W& E/ F6 Q
" t1 v( f* i. n4 s& Y5 B) |
turtles-own
* m: S) X/ Y( K" r7 ?[
0 J9 H" t0 w! |; @" {1 _  speed     ;; the speed of the turtle
' I6 c2 \0 S# x* T1 B: W1 U3 k$ B( x$ @  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
2 `! ]8 x. j8 w( ]$ ^3 i  wait-time ;; the amount of time since the last time a turtle has moved
8 n% {& y5 W# l& c, T0 ]5 H9 ~: M4 s* h]) G) E# u% \2 ?  C3 p& g$ n3 l4 N, Y
) o5 W' L+ A1 l# b$ g' k% _
patches-own. G7 S* o- A& |: Q  c
[( }: \3 b! O2 y
  intersection?   ;; true if the patch is at the intersection of two roads
6 A/ }" a, P5 ~1 n+ U$ \+ {) r  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.1 G$ I4 H' b$ y  I! @
                  ;; false for a non-intersection patches.. k6 r" ?9 ?- k' a8 D3 C* f( y' e& B
  my-row          ;; the row of the intersection counting from the upper left corner of the: E# z# M& c* e3 {
                  ;; world.  -1 for non-intersection patches.# c) ]) v8 Y4 U  ^. K5 `2 i! s
  my-column       ;; the column of the intersection counting from the upper left corner of the
( ~/ ]  y" c" V- g) c                  ;; world.  -1 for non-intersection patches.
7 M2 i/ F7 K9 n3 w% V1 ~4 q8 L( O  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
  {: [! V+ [  \  r! M- ~6 |  auto?           ;; whether or not this intersection will switch automatically.7 F* `& a' E* f, O+ m
                  ;; false for non-intersection patches.
  i+ k+ Z6 ~! T, g* d]5 F0 `; b9 Y4 w! P  R0 t0 A

! H6 m: J  b: X+ Z& _" v, c; B  ]9 t! ]  I) P  Y  k$ c$ c
;;;;;;;;;;;;;;;;;;;;;;
) E9 s! w. \0 P4 ^+ v8 e$ v;; Setup Procedures ;;1 u. m" O2 H1 w; E, L4 s6 H0 j
;;;;;;;;;;;;;;;;;;;;;;
  O" a( \0 ?6 c& ^: w
& H7 A/ A4 X( w5 x2 p/ w;; Initialize the display by giving the global and patch variables initial values.
5 H) [/ [8 _5 Q7 y9 n;; Create num-cars of turtles if there are enough road patches for one turtle to
' ]$ y" o8 s9 G* g. ~8 l;; be created per road patch. Set up the plots.
9 N8 e+ a0 {1 z0 X( P' F: C' e' Qto setup! s2 Y; M' a1 y8 a' }
  ca
. U/ e3 @* F5 y* }, s  U4 x7 n  setup-globals
* t) Y/ h5 L7 N9 A& e
/ g: A4 C/ g' v1 o2 L* E4 y  ;; First we ask the patches to draw themselves and set up a few variables" ^( j5 O5 v" ?7 g& f, K9 A1 g
  setup-patches
1 ^5 J" ~3 @* Z! b6 q  make-current one-of intersections+ |$ H5 n6 q/ E1 k3 X. y! N! G+ F
  label-current5 v( l3 d+ }5 Q) }. L) V

5 P( a# [/ h) h  ~; a- ?  set-default-shape turtles "car"- q# b; ^' W; k
2 V8 T0 O1 h' i( U, q
  if (num-cars > count roads)
) g8 A$ \0 ^& w  [
. M' `# S0 {4 q' [/ L- V& y/ `    user-message (word "There are too many cars for the amount of ": l8 W9 a" a' B
                       "road.  Either increase the amount of roads "
( Q" _  x/ |6 v* F                       "by increasing the GRID-SIZE-X or "
( T- ^5 c. |( E+ y) P+ k0 Z                       "GRID-SIZE-Y sliders, or decrease the "* W3 K$ ?6 F; e' j6 Y/ L) R
                       "number of cars by lowering the NUMBER slider.\n"7 P3 C9 D$ o+ u8 N: ]7 `
                       "The setup has stopped.")# ?& p5 a2 i% g+ z3 B
    stop
5 p$ J% P' L  c8 C$ x  ]  E9 c7 w: _4 B* l7 f9 h
8 C$ }" D3 L* j3 j) V8 Y' \
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color; F! e0 f$ Q' D3 S
  crt num-cars
0 i' D" q9 C3 A" p( l  [  `& C7 c, b* `& \
    setup-cars5 t$ k- g& p8 V! U3 o3 n' Q
    set-car-color8 O0 \1 p' ?7 p4 a% N2 k5 Z, Y
    record-data8 |3 F4 ~) W8 k4 W
  ]8 [# O+ @7 w! n! G! ?0 d
# b: T( P5 w! N4 p7 M
  ;; give the turtles an initial speed
# r* z; m/ c3 |  ask turtles [ set-car-speed ]! n) v1 @- z  u+ p, Q

/ o% O" ^1 r3 c* @2 T. L  reset-ticks
2 q  Y. j- ?( M; bend
) U, U- o7 I3 D  F7 {4 ^
6 F: \; ^) l$ a0 U" X2 ]  F( ~;; Initialize the global variables to appropriate values
! F! t% q) D6 Y% a% O7 zto setup-globals
) I, Z9 r& V1 B1 N( T  set current-light nobody ;; just for now, since there are no lights yet
$ y2 s3 @* T/ B. r$ v7 C9 I  set phase 0/ @  Q! o; w3 H; g. ^
  set num-cars-stopped 09 A) X+ B$ T+ ^4 _
  set grid-x-inc world-width / grid-size-x4 E6 i$ f% B4 D- i7 g
  set grid-y-inc world-height / grid-size-y
( |/ H; a3 q, R- Z$ Z! v8 w' C2 R+ x. S* Q" _' }
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
+ d0 d* E- t& f$ ~% b% _  set acceleration 0.099' [/ m8 e! p5 @& F. R- s1 w
end2 k+ t0 K- v* L# X

* ]  ^- T3 S% p9 c% o' V! \! |" S;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
  J: j& {% _0 ^) g  n7 G;; and initialize the traffic lights to one setting4 \: O4 O9 s& U! `! R
to setup-patches
- G; T9 h5 K9 k- f  i* o  ;; initialize the patch-owned variables and color the patches to a base-color
2 A, v5 u& r9 j) B! W  ask patches
1 {5 c- c7 e+ U8 v2 P  [
, n1 ~; |# G7 K    set intersection? false& a! G0 |) X/ |) ?/ M. {5 B1 T0 k6 I
    set auto? false
0 I, e  v3 E- @" U- S    set green-light-up? true
" |  |$ ^7 }; I6 w' {8 c. g    set my-row -1
; Z* _# \; i$ M) M3 g    set my-column -11 a  Q+ F- H3 `/ ^$ X
    set my-phase -1! v$ F# [, ~0 _5 B7 B" j/ {1 _
    set pcolor brown + 37 F( t+ M9 {0 _0 l$ n
  ]5 B7 }- t9 w# q

5 i( D# K/ W$ v; z5 T" N  ;; initialize the global variables that hold patch agentsets; L; V. u( s. d. {  o
  set roads patches with
' X) F  w6 {5 ?7 K, y( H; v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or8 V# f* y2 w$ ^/ A0 E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 H  q( @4 \0 _9 s" b  L7 |
  set intersections roads with
: H$ z# \" U# B) ^    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and! d$ _5 T7 u( {; Y& p7 U
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: W6 s5 ^# S& `1 _

' o. x  L$ Q" p3 X  ask roads [ set pcolor white ]( X5 F& _' m# T8 U  P- S0 d
    setup-intersections
6 W9 X# `. ~, ?( N' p3 a4 ]end
6 ?8 r; e1 M' g. I' r5 l3 |0 S其中定义道路的句子,如下所示,是什么意思啊?
' `0 p& J1 U6 R, E) ] set roads patches with- P; E' ?9 L3 H( k* _% \
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 x' e9 [- k) Q5 @4 F' F
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* D3 J7 N& C' h0 Q+ 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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