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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。' A' z, D7 A3 j  _* L! R. b+ O
netlogo自带的social science--traffic grid这一例子当中,
  i* P- h# g8 E/ Z7 ?  mglobals
. d0 ]/ @. E. h, @5 ]/ P. w[8 O: J5 G' O" w! @1 R
  grid-x-inc               ;; the amount of patches in between two roads in the x direction+ F2 l* u. @4 w' |2 o0 R
  grid-y-inc               ;; the amount of patches in between two roads in the y direction/ J6 B4 Y+ Y) i, v5 V' s
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
: l4 b0 E, M" Q- ?- v8 m                           ;; it is to accelerate or decelerate2 `" ?. A. n9 x" P* b& @- M
  phase                    ;; keeps track of the phase
. ?3 F: z& G) p. \; }( ^  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure+ b: L% c0 U6 z6 K/ b
  current-light            ;; the currently selected light, o% d  ?$ [0 |, X. N! H
$ t8 z, [# |+ N# b. T
  ;; patch agentsets
# @4 v, Z! g  _( W8 T9 ^" w  intersections ;; agentset containing the patches that are intersections8 o/ W2 R+ s6 @! r6 w6 |. V) O( [
  roads         ;; agentset containing the patches that are roads
3 x$ s/ v8 I( H, Z. \. t$ s: O]' |9 h  h4 B! v

3 E3 \' j6 N9 k( _3 L2 Q8 vturtles-own# L3 M# L- P' P/ s; U% T
[
4 Y# F1 E- W* P9 s  speed     ;; the speed of the turtle* A1 w% S1 y3 {4 ~$ i2 B
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right0 f) d* A4 h/ R1 c$ b( L' ]
  wait-time ;; the amount of time since the last time a turtle has moved& o/ b: ?" G, a# f# Y$ C  K
]0 N) u- l# R7 c( ^3 y- m$ [" D6 @
$ F' u; t& T8 V) u# I1 G. v
patches-own
& F6 a- O* I8 s9 @4 \* f. _0 H[" N: }8 t8 U, V" _+ S- c
  intersection?   ;; true if the patch is at the intersection of two roads4 O2 D# k; B8 v$ f% ]- ]
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
! H1 r/ W5 R! e                  ;; false for a non-intersection patches.' Q/ T0 o" E7 b+ F% W
  my-row          ;; the row of the intersection counting from the upper left corner of the2 D& K# J9 u' T& x2 o
                  ;; world.  -1 for non-intersection patches.
' g0 y; `- T4 H4 `7 V- d. R; P. [! {  my-column       ;; the column of the intersection counting from the upper left corner of the
2 ?" _" r; q. E- I8 u1 N                  ;; world.  -1 for non-intersection patches.; c' H- b: G0 u" A* H7 m
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.. B# @8 C- \8 N
  auto?           ;; whether or not this intersection will switch automatically.9 P9 i7 p/ J; G# [  t
                  ;; false for non-intersection patches.
, Q; i% g% ~% v7 ]- h, Q]; [% k: d6 _# |: V
8 D1 J/ @) j- v# v* q$ d9 L4 [

# e+ Y& ~+ n9 v1 |# l;;;;;;;;;;;;;;;;;;;;;;" Z/ _. M& }# c% y( z+ k
;; Setup Procedures ;;) ?) v1 g7 s4 [9 A
;;;;;;;;;;;;;;;;;;;;;;" O' C8 N7 t: L: b  w. V) v
  b3 u5 o3 i& Q4 s+ j
;; Initialize the display by giving the global and patch variables initial values.
  k- U  x' M( K9 q. ^& h- R2 Q;; Create num-cars of turtles if there are enough road patches for one turtle to
+ Z0 Y1 ?7 ^* W7 O, Y. L;; be created per road patch. Set up the plots.
' u: x: o& D& a6 G* wto setup: X& F( E% l2 @. T1 ^- w: Q
  ca  k8 U+ [1 D, y
  setup-globals
+ _; [3 a  l5 H! I: w
+ ]' |$ x- a1 B( O8 ?  ;; First we ask the patches to draw themselves and set up a few variables
- M- l: ~. `! A) J- }* F8 {8 ~  setup-patches
" r! P) L  k4 w; D# Y0 o* V  make-current one-of intersections# @8 v& }3 M+ S& a2 z
  label-current
/ z( Z7 F  q2 G. H* d8 k7 B: T8 ^6 Z/ X3 @
  set-default-shape turtles "car"4 r8 T# H  ^$ W$ g& L: d1 x- S# A

0 l1 O5 |' Z1 e9 n' n9 ]4 _" U  if (num-cars > count roads)+ J* r4 v7 z! |0 F, u6 s6 W
  [
/ y/ s, _/ ?+ ]: {! v3 b* R    user-message (word "There are too many cars for the amount of ", P6 ~) k$ c( H% E+ o, k; V! z- D
                       "road.  Either increase the amount of roads "0 X' N+ x5 T1 C3 ]+ n; b
                       "by increasing the GRID-SIZE-X or "
5 |* Z5 j; k% T9 |  z# R- H) J                       "GRID-SIZE-Y sliders, or decrease the "
1 g3 N4 t0 G2 R                       "number of cars by lowering the NUMBER slider.\n"
) F/ ~1 |. I9 a( E5 b7 M# d2 R( T' \                       "The setup has stopped.")
* k) B' t/ l$ h$ ]: E  n9 ?1 O    stop
* g) g% U# r$ J- W* l) F' P  ]
) h3 j" D) K9 q, W& K5 a
7 b+ T4 g* W" A0 ]/ t0 f  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color3 `& f4 u" K" `# l+ d/ k4 ~) C1 o) L; y
  crt num-cars
) B1 l8 D& ?# P# Z  [4 i+ L; ]5 P5 b, A5 W) `! ?8 W
    setup-cars
  @5 _- n$ N* I# n    set-car-color
4 r! P# R. x5 p: B1 I! ]  g5 j    record-data
& \; V  b# Z5 B" {: A. U  ]: I% i8 W5 ^" E0 l$ \% i
. L/ ?( x' f0 H* e, V/ b
  ;; give the turtles an initial speed* x' x, q* \0 R" ?
  ask turtles [ set-car-speed ]
+ M3 z& @; k; Q
6 ^8 [# ~% l+ z  reset-ticks
& L- E( x0 {$ e. w$ c" Wend
2 B+ G$ o& h; ~" Y5 R- a- ^4 G
4 e+ u' J6 ?# W/ B) [;; Initialize the global variables to appropriate values
# X! x+ p  T# @6 fto setup-globals8 q( m! p  l5 D' ~0 V6 z! y" q
  set current-light nobody ;; just for now, since there are no lights yet2 ^/ i4 u$ Y3 L; @) A& I* d
  set phase 0( |1 B1 U7 u; T& A9 Y" A$ n
  set num-cars-stopped 0
2 m4 U) q8 f$ x0 ?  set grid-x-inc world-width / grid-size-x
$ ]9 Z+ R: G1 z4 X  set grid-y-inc world-height / grid-size-y  `) q! \/ u7 [) I5 ?' I9 V3 }

+ X' }6 b5 E: q  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary+ `3 g4 |) h9 L" A; n& Q
  set acceleration 0.099
) g  p$ B6 [; e/ Tend
8 R: e7 o0 ~9 y/ d
5 o8 x5 L2 F! I* _1 p" A$ P;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
: \0 o2 V7 b) a% u! t( C;; and initialize the traffic lights to one setting
/ E6 `: g5 O% }/ eto setup-patches
. _  t( W& D: j% K! U) C2 j$ m  ;; initialize the patch-owned variables and color the patches to a base-color* J* N7 t* }, i( l! @
  ask patches; W1 M5 a/ w( |, ~' g
  [
9 e) T  c8 o/ B3 A& Z& P    set intersection? false* \% D# L- s' k$ t; s
    set auto? false
  I  Y' ~6 m& [    set green-light-up? true" o+ e7 Z1 k, k/ V
    set my-row -1
& e2 L5 {! m: w! ~% \    set my-column -1+ v8 C$ k2 n( Y* o' V
    set my-phase -1+ d. W9 n7 w% m! X  `/ x
    set pcolor brown + 3
8 i$ z) N% Q( i' Z  ]# s) u3 F) B, r. }) u
, ?- p( R( K/ H% d
  ;; initialize the global variables that hold patch agentsets# T9 }, S, N1 K/ r
  set roads patches with9 {& |  U$ N( j
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* }, B1 h0 P' x  b: j& g6 U  V9 J
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- i5 w/ s4 C. T$ S" W$ z& w& A  set intersections roads with
0 `# u/ G7 m9 E% Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and: V& `- f* A! a  J" i
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 _- s! V3 B, L2 z' P
& X4 u2 C0 u9 j# t; @
  ask roads [ set pcolor white ]
! B; J& `8 m( _9 Q; D    setup-intersections" q2 n$ r; W7 w) |, \
end0 A) s! M: E- ]3 ]% p4 G' {
其中定义道路的句子,如下所示,是什么意思啊?8 Z, _  o& x4 r
set roads patches with* d% O: l& e/ E4 I
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 p) a0 J. W9 L6 O+ `- l
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- g4 }/ ^7 C$ w$ r6 Q: r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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