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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- `. }+ g. C+ Y5 B7 ~
netlogo自带的social science--traffic grid这一例子当中,
# g1 O5 [' o6 @; q: ?+ c- R" Y4 \globals
& x2 `4 a  Y6 L* @7 X9 N8 [[1 ?( ?, ?% n3 W" v
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
! C2 C$ S6 \4 x7 C. ]  K2 s9 N  grid-y-inc               ;; the amount of patches in between two roads in the y direction4 l& X5 m. T% e; O
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if+ l4 p; U; d. j$ A6 T, r
                           ;; it is to accelerate or decelerate
7 o9 t# {( w/ D% E: t& L  phase                    ;; keeps track of the phase
; y- ?  L( s( R% j1 ?7 _! i5 x3 t  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure# Y! k' c9 i" O+ l8 E) S3 a/ N
  current-light            ;; the currently selected light
! h5 N6 u" \2 [
8 [4 v# C' }6 R' I4 a  ;; patch agentsets# F0 [$ N' M; S, N( h/ S
  intersections ;; agentset containing the patches that are intersections
3 ?! ^4 ?4 {% k& @2 g/ L2 q2 m7 L  roads         ;; agentset containing the patches that are roads
) e: b! o8 i- e0 i]
# d1 |) w: y8 p8 M$ d' Q
4 U! z/ r) i( q& ^turtles-own6 V' z1 S" \9 `2 x8 i
[
, I/ a8 e9 p3 P  speed     ;; the speed of the turtle
! d# Y/ |7 g: w% L. g  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
- J4 z# I& }( H2 L5 p  wait-time ;; the amount of time since the last time a turtle has moved& K9 x' Q3 o8 G4 N; @, i* }
]* n. v0 W, \6 z3 F/ p' \4 N' ]7 @" Q
& B, r) \3 d1 x/ ?( }) L
patches-own
" a" X0 P- d2 s' E2 {$ L[' K$ k& Z2 `6 F# C5 e2 u3 F$ K9 R
  intersection?   ;; true if the patch is at the intersection of two roads
/ k$ s4 e0 X- s) y  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
' A* g7 P7 K1 f                  ;; false for a non-intersection patches.) a( D; Z3 w- Z1 Y: s
  my-row          ;; the row of the intersection counting from the upper left corner of the7 Q$ X* o+ S1 l% Z
                  ;; world.  -1 for non-intersection patches.  [0 ^7 q* S7 t6 |4 ?% w% _6 I' C
  my-column       ;; the column of the intersection counting from the upper left corner of the
6 r' C. ]; O6 p. V0 e$ _* e                  ;; world.  -1 for non-intersection patches.7 ]/ }5 x2 S( L2 l; l/ z( n
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
( m4 B$ [( m' x9 `1 Y  auto?           ;; whether or not this intersection will switch automatically.6 i, H- V4 D0 B5 E1 o1 ]
                  ;; false for non-intersection patches.
/ ?$ B- |6 `; b( l1 c6 ?]
9 }- i  G! ?4 a. v% V* J
* I# H" S. H4 _
) F5 T; M. j9 [: h( S4 g2 L9 x2 _;;;;;;;;;;;;;;;;;;;;;;0 ?; Y9 G+ j; |# ^! X4 j- F
;; Setup Procedures ;;: [, ^/ _' O" k% H! Y
;;;;;;;;;;;;;;;;;;;;;;' u6 z. N1 e9 d  Q2 B, y0 k

* n/ z+ Z8 B' ]' ]+ i;; Initialize the display by giving the global and patch variables initial values.
) D. G$ r) h$ i0 [" Q;; Create num-cars of turtles if there are enough road patches for one turtle to3 P/ v& {( j7 ]2 |0 r/ q
;; be created per road patch. Set up the plots.& V7 ~; f% t6 M. ]
to setup
4 n+ P1 k' M4 o  ca/ q% ?3 ?4 p# ]2 L& q, V+ U
  setup-globals
* l* a3 d3 h* D: B
' |5 D# v! H# ~1 M, H  ;; First we ask the patches to draw themselves and set up a few variables
1 k% L% U- V! }" d: F+ G8 v  setup-patches
! r" G2 h5 i* a. s3 H  make-current one-of intersections" w  J9 W2 g4 ^' \
  label-current
& b% C6 f% e0 v1 l2 }( j8 X8 u. O# d" Y) v4 ^
  set-default-shape turtles "car"
. L+ |1 C+ ^6 e! k  e- Q1 K1 d% F
2 P. v: H  ^/ N  if (num-cars > count roads): Y# U. K) @' Y! E' q& Y
  [
+ T) i5 b3 w6 N" F) V/ r! K    user-message (word "There are too many cars for the amount of "
" K4 t- ~$ M  t4 ]# {                       "road.  Either increase the amount of roads "2 m; ?5 W: H" I# Y+ k
                       "by increasing the GRID-SIZE-X or "
1 G9 O6 M# S. ]) B3 @% K                       "GRID-SIZE-Y sliders, or decrease the "
/ w* V! v8 i2 W  P3 c                       "number of cars by lowering the NUMBER slider.\n"( s5 \2 F' M5 N& p3 S  D* Z+ ]
                       "The setup has stopped.")) r" ^# B% J' D! G& p1 F* g# \/ e
    stop" T' {1 a9 N, K' O1 a" h7 m7 ~/ z
  ]
3 y4 P9 {! E: A! h) A- ^# T$ F" I7 m$ z. Y& B' h+ e
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
6 c$ G6 ]/ \1 C  crt num-cars
- [3 ~4 ?" P( |9 n2 W  [
& a7 j/ O5 p; q6 f8 e& A  C    setup-cars8 h# c' c+ ^! Q) L
    set-car-color8 J0 l- ?; L- q3 L% n' x
    record-data
6 Q4 w2 C6 i( @4 C# t+ u  ]
3 H8 [8 X8 |2 w$ c: r1 d9 r$ _8 o! N9 m4 P, B: E0 B2 G
  ;; give the turtles an initial speed
8 G& M5 E; V+ i8 P" X1 e4 a( n, S  ask turtles [ set-car-speed ]
& S$ z' j  ?7 F1 I' [& Z1 ^4 M- B) ^
  reset-ticks
; [; q9 g) i2 A) ^, l) Z; N( pend
) N7 }( H  Y7 g. L+ N4 ?
$ v4 h5 \$ t4 D' Y* }" }5 c;; Initialize the global variables to appropriate values
$ ~2 m2 d( W+ S# U+ S1 O# Q8 Lto setup-globals. C7 I/ B5 @+ D: d1 s
  set current-light nobody ;; just for now, since there are no lights yet
. A( q, k8 C* d8 V5 [; Z  set phase 0
) Y$ ~- O, u# M" X' H2 R; N  set num-cars-stopped 0) o: J, j) X+ O* M: f& o2 f# z
  set grid-x-inc world-width / grid-size-x& C2 C: F! B; A3 R8 ~* O
  set grid-y-inc world-height / grid-size-y' D3 O* o% a# P; F  y- t- J" X$ O
: }7 Q, @$ d: j, Q1 Y+ ?
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary- A4 H2 [! A* T" k4 ~7 T% x" ]2 ]% c3 L) L
  set acceleration 0.099
- X3 G9 {6 y- q& M% hend
+ ]( P! U- V) R! l5 R; \! s- M2 ]/ I( g; d) ~
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
' l+ l$ T# @% x;; and initialize the traffic lights to one setting  x0 |% P2 F( u2 v# e% s
to setup-patches
- }( x9 W# A2 s- y; E  ;; initialize the patch-owned variables and color the patches to a base-color. B4 ?! R: P, S+ J, V0 n- [1 k# p
  ask patches9 q+ A* }+ q3 ~
  [
1 [+ O+ R& Q: N# S2 A    set intersection? false
: d1 m. X/ h1 `' j: L* p    set auto? false# U& h+ E3 T& T$ V* p+ M  ~
    set green-light-up? true
4 c9 N  s8 v' a2 F  q9 U! y# J    set my-row -1
, G( S4 m7 `, b5 {    set my-column -1
2 G8 o" q- [! A    set my-phase -1
% X, }$ [' m$ C! q& Z    set pcolor brown + 3
- s. _5 P' Q; j/ d2 t  b  ]0 s6 z5 n% b! p- U/ [6 L! e
+ E, D. e) `7 o* x! a
  ;; initialize the global variables that hold patch agentsets
5 u- ~8 C- j# ~) g6 }  set roads patches with) M6 V' k/ q4 @- B2 {
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 B- }: Z; k8 I& I) _2 i2 M    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 t: [8 P% n# b' R+ B- M# n
  set intersections roads with
4 C; h! [( e3 n/ [, e: F9 P/ m& D2 @    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ B* k/ G* A: J
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ W9 F0 J- g- k9 U9 I! }3 E% L' K# j
  ask roads [ set pcolor white ]
4 }  f4 V" U3 W0 Y# e    setup-intersections
: W2 O8 }- y: b+ Zend! Q/ |9 {# e) e. n' c
其中定义道路的句子,如下所示,是什么意思啊?
0 T$ j1 Y% S9 t set roads patches with; X+ H) Q1 m' f; x1 A( F+ m
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: N$ d# b% ^1 Y" E9 A  p5 R
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; u: m; n" w4 C% [/ V% A% t8 P
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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