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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。, K4 y7 n# n8 j1 q2 Y+ @6 _
netlogo自带的social science--traffic grid这一例子当中,
8 _7 J+ k* K6 mglobals5 ]+ Q3 z( \& N2 j$ ]8 R
[
' G" Z0 y! T8 _0 \  grid-x-inc               ;; the amount of patches in between two roads in the x direction: t( D3 f/ l# N6 d: S2 P4 p
  grid-y-inc               ;; the amount of patches in between two roads in the y direction5 q$ W" Z7 I' y
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
. Y) {- r* R2 G6 r+ c. R7 k& d                           ;; it is to accelerate or decelerate
% k5 c: T2 U0 b6 p; B  phase                    ;; keeps track of the phase
2 y* x- y4 @% [# @% F, i  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure+ r6 Z) v' ^$ D
  current-light            ;; the currently selected light
2 W  ^: z5 q- m1 w8 v2 D6 X) h) K6 J* E. U. ^& |/ @3 v/ `
  ;; patch agentsets
. I& H" `* Z1 G' q; b) R  C  intersections ;; agentset containing the patches that are intersections
/ @9 v  q# z7 f  z3 `  roads         ;; agentset containing the patches that are roads
. f& a( h8 [' [- i, M" k% _; ]- |]
- u* p6 l9 A/ K3 `* m" q; V, e5 U- V; r5 Y- o7 W
turtles-own
5 I  l3 _# c2 f2 f$ d  [0 {[% n2 h( l* a. U! w: K3 V( Z: Z
  speed     ;; the speed of the turtle1 {3 x# L$ v+ P  m& N
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right' P  n# [3 l2 e2 c+ A
  wait-time ;; the amount of time since the last time a turtle has moved
. z' `' g0 h" h/ z( y  L# o]9 E" k# v3 M. h+ P6 o8 e
/ \/ N- l5 h( c2 q) F- P
patches-own
5 r% D4 J/ l! \; c% h$ I" F0 a5 Z[
# n, a( c$ ]5 q' ~  intersection?   ;; true if the patch is at the intersection of two roads' Z1 E% u% [7 O5 }" F
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.; L4 j; B) Y" J; Q$ }( Y: p7 L$ B
                  ;; false for a non-intersection patches.; c. E& K0 K0 s" j4 F0 b0 k  m5 j$ \
  my-row          ;; the row of the intersection counting from the upper left corner of the* p3 i# m& w: t$ y
                  ;; world.  -1 for non-intersection patches.$ ~* ^" a$ h6 |
  my-column       ;; the column of the intersection counting from the upper left corner of the, O7 u2 {- s5 Q, w3 P8 I# f
                  ;; world.  -1 for non-intersection patches.4 c9 k% ]$ l& E2 {  i
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
. K3 ~: F: U3 W& Q) g& ^- S9 M% g5 J  auto?           ;; whether or not this intersection will switch automatically.
9 {. @/ l3 H: f2 r                  ;; false for non-intersection patches.
  `! P) c) I4 j& y7 I]- |7 I) x' C& Y8 o
5 T& W+ \) h0 ]0 q0 W% d  q

) T! i" S$ Q6 Z: b9 A6 }1 V* e;;;;;;;;;;;;;;;;;;;;;;
" E  g' V, O$ t% Z3 G5 ?. K$ p;; Setup Procedures ;;
  b$ l: {8 O2 X5 c+ r5 `;;;;;;;;;;;;;;;;;;;;;;" \4 ^+ P; F4 B! f

! T) a( w$ P+ A4 S;; Initialize the display by giving the global and patch variables initial values.! Z/ M% v2 o7 S( Q' Y
;; Create num-cars of turtles if there are enough road patches for one turtle to$ W- O6 k1 L3 e" L  a3 y
;; be created per road patch. Set up the plots.* \6 u9 P+ ~- V9 J2 ]
to setup
$ L2 H3 k  T2 r- @. N* |  ca6 Q2 s* Y2 j- O& u; [# t" i
  setup-globals
1 o' I& c) Y1 J
# K+ z5 j" k9 \1 t- z8 U7 ~  ;; First we ask the patches to draw themselves and set up a few variables
: K/ G& ]) I: i% U3 Y7 L! ~  setup-patches
; \. U* i2 L) M$ |& f% W  make-current one-of intersections
7 x) j" A' l8 x9 [  label-current- I, J: L. i: L- l- }

; B, j9 Z0 z1 X& T, N  set-default-shape turtles "car"
: @4 o& u7 ?  v& ?1 ?6 W/ t" I% d0 N  d
  if (num-cars > count roads)
+ E* A8 t$ m8 L* t  [0 S& d  e) i7 `( I" H0 T" Y
    user-message (word "There are too many cars for the amount of "8 D; {# T6 _/ }+ p9 j. ~
                       "road.  Either increase the amount of roads "; O! I3 i6 u( g) Z6 v. h6 T4 X
                       "by increasing the GRID-SIZE-X or "
) b# r9 a3 j0 G6 o+ s4 V. i5 }                       "GRID-SIZE-Y sliders, or decrease the "
# [( L* Z! C, [: w5 i                       "number of cars by lowering the NUMBER slider.\n"
% B: H" O+ Z1 X                       "The setup has stopped.")
0 |7 q1 F5 _: T8 l    stop  B4 j# f7 s, b$ A1 l
  ]
7 ^% b9 v" r! Y& `- U4 u9 w5 G" ^, a5 D& {5 p
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
' L$ p* e$ k, F) ]$ c5 X7 X8 |8 {  crt num-cars7 M$ F3 w' |/ _- J$ `/ u
  [; H& ^9 [5 t/ v# \% N
    setup-cars
( t) x5 S, ?) i  e9 y6 T- z% l    set-car-color7 |4 \8 Q' {* G. K; z
    record-data" t- j! x8 G5 d7 \2 v
  ], k2 j5 \; E' B' z

8 H3 o! v0 A$ j, X  ;; give the turtles an initial speed
& ^9 T# \7 z' x/ z& C  ask turtles [ set-car-speed ]1 [* w3 _- h6 |1 k, M7 [- f# Q
* `( B6 q: w: x, I$ _! x' u
  reset-ticks8 @$ i: N( d) R( I7 N% M
end
* w: s1 d# v. M
. Z6 G4 C5 C: q8 G1 |3 h;; Initialize the global variables to appropriate values0 ^' z+ \- [! T
to setup-globals7 G2 Z+ O$ F3 Q/ t: E) s
  set current-light nobody ;; just for now, since there are no lights yet
, v1 @. w7 ]4 ?' }+ S' M/ o  set phase 0( r0 C9 s+ d. F# U* C/ l0 k7 J, c# B7 j
  set num-cars-stopped 03 J8 O9 v/ m0 A
  set grid-x-inc world-width / grid-size-x3 [1 @, ?  ]7 r6 u
  set grid-y-inc world-height / grid-size-y; Z+ }" R5 y% ~" h6 @
/ x$ R) U; M, ~5 U+ y+ u
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
: v* n+ L9 Z+ @' M  set acceleration 0.0999 q& v# M" f: `% ^; F5 t6 `
end2 K  M  A# i; e* d2 n
4 T) L& P$ F' \4 G
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
0 i; ~3 U; P! h: x9 a# n;; and initialize the traffic lights to one setting
3 W: A% V2 Q2 }to setup-patches( ^. u) F0 m$ b& n. J
  ;; initialize the patch-owned variables and color the patches to a base-color
* J1 N2 s( B) K+ U0 E3 F  ask patches
4 z) M' [, C( q7 L. S  [
( ?5 v5 y1 R4 R+ k+ \! z    set intersection? false
3 b" ^# ]4 s. N. S# ^5 v    set auto? false0 |" n  r+ L; f3 @
    set green-light-up? true
% h& a: p! L, O; F# |3 Z" r    set my-row -1
/ Y9 K& @4 R- z$ V# N2 ]; s) p    set my-column -14 }& \( m" m- F1 m
    set my-phase -1
/ g5 d& X) V% J$ N& P: S+ Z: c    set pcolor brown + 3; G* N: e/ U9 n3 c/ o5 z
  ]
' R2 \* @5 j4 K( e: c
- J& m) B* X* l- W  ;; initialize the global variables that hold patch agentsets4 g; D) d6 \, G
  set roads patches with
7 ]. i( U- v4 r$ J' x, J    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. i, Z$ m2 J1 d+ J    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" n6 t1 v: H. f  set intersections roads with6 {" C7 f* y, L% T
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and) H, j0 U/ R4 e1 v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  {% n' a* T5 L+ j* G! N- w4 M1 ]- ]

# \! S) y8 G& P0 o$ ]  ask roads [ set pcolor white ]
' s5 b6 z; g! M5 `. u+ t/ |9 }; ~    setup-intersections
" a# }1 u6 c9 h3 [& ?& [0 vend4 J4 m  c) H7 b7 t, b8 `/ E/ k
其中定义道路的句子,如下所示,是什么意思啊?
  P) T  G( f7 D9 w/ K. ^9 z set roads patches with
6 [" S: `8 W7 l- U& i6 b6 I9 Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# a7 h; D# X$ Y7 j/ H    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: k, ]2 u" d- I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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