plots a web
Description
plots a web, based on a flow matrix
Usage
1 2 3 4 5 6 7 8 9 10 11  plotweb(flowmat, names = NULL, lab.size = 1.5, add = FALSE,
fig.size = 1.3, main = "", sub = "", sub2 = "",
log = FALSE, mar = c(2, 2, 2, 2),
nullflow = NULL, minflow = NULL, maxflow = NULL,
legend = TRUE, leg.digit = 5, leg.title = NULL,
lcol = "black", arr.col = "black",
val = FALSE, val.digit = 5, val.size = 0.6, val.col = "red",
val.title = NULL, val.ncol = 1,
budget = FALSE, bud.digit = 5, bud.size = 0.6,
bud.title = "budget", bud.ncol = 1,
maxarrow = 10, minarrow = 1, length = 0.1, dcirc = 1.2, bty = "o", ...)

Arguments
flowmat 
flow matrix, rows=flow *from*, columns=flow *to*. 
names 
string vector with the names of components. 
lab.size 
relative size of name label text. 
add 
start a new plot ( 
fig.size 
if 
main 
if 
sub 
if 
sub2 
if 
log 
logical indicating whether to scale the flow values logarithmically. 
mar 
the figure margins. 
nullflow 
either one value or a twovalued vector; if flow < nullflow[1] or flow > nullflow[2] (if two values): flow is assumed = 0 and the arrow is not drawn. 
minflow 
flowvalue corresponding to minimum arrow thickness. 
maxflow 
flowvalue corresponding to maximum arrow thickness. 
legend 
logical indicating whether to add a legend with arrow thickness. 
leg.digit 
nr of digits for writing legend  only if 
leg.title 
title for arrow legend, e.g to give units  only if

lcol 
line color of arrow  not used. 
arr.col 
arrow color. One value or a matrix, with same dimensions as flowmat; if a matrix, each arrow can have a different color. 
val 
logical indicating whether to write flow values as a legend. 
val.digit 
nr of digits for writing values  only if 
val.size 
relative size for writing values  only if 
val.col 
color for writing values  only if 
val.title 
title for values legend  only if 
val.ncol 
number of columns for writing values  only if

budget 
logical indicating whether to calculate budget (sum of flows in  sum of flows out) per component. 
bud.digit 
nr of digits for writing budget  only if

bud.size 
relative size for writing budget  only if

bud.title 
title for budget legend  only if

bud.ncol 
number of columns for writing budget  only if

maxarrow 
maximal thickness of arrow. 
minarrow 
minimal thickness of arrow. 
length 
length of the edges of the arrow head (in inches). 
dcirc 
if cannibalism (flow from i to i), offset of circular 'arrow' 
if 
bty 
the type of box to be drawn around the legends ( 
... 
extra arguments passed to Rfunction arrows. 
Details
This function is less flexible than function plotmat
It is meant for visualisation of food web flows, that are inputted as a flow matrix.
It displays the elements on a circle, and, where there is a mass flow, two elements are connected,
the magnitude of the web flows is reflected by the thickness of the arrow
Note that the input matrices from function plotmat
and plotweb
are transposed.
Author(s)
Karline Soetaert <karline.soetaert@nioz.nl>
See Also
plotmat
,
Rigaweb
, Takapotoweb
try: demo(plotweb)
Examples
1 2 3 4 5 6 7 8 9 10 11 