Description Usage Arguments Details Value Note Author(s) See Also Examples
View source: R/variableTransformation.R
The smooth transformation function is a smooth version of the
ecdf
. A smooth density estimate as well as the inverse
transformation (the quantile function) are also returned as attributes.
1 
df 
a data frame. This data frame should contain a variable

vN 
a character string corresponding to the name of one of the
variables of 
low 
a numeric, the smallest value of variable 
high 
a numeric, the largest value of variable 
delta 
a numeric, the bin width used to build the variable values histogram. This histogram is subsequently smoothed. Default provided if missing. 
alpha 
see 
... 
additional arguments passed to 
The smooth mapping to uniform function returned by mkM2U
is
obtained by first selecting a subset of the variable values for which
the variable time
of df
is between low
and
high
. The values are then binned between the min
and the
max
of the (complete) variable values with a bin width
delta
. Function ssden
is then called on the
histogram and the result is stored in object ii.fit
(This
object is stored in the closure
of the returned function). The returned
function is the result of a call of pssden
on
ii.fit and the argument.
A function inverting the "mapping to uniform function", that is, a
quantile function, is also returned as attributes
qFct
. This
inverse function is obtained by numerical inversion, calling
uniroot
internally. Additional arguments can be passed
to uniroot
via the ... argument of the function.
A function returning the smooth density estimate is returned as
attributes dFct
.
A function returning the probability for vN
random variable to
have a value smaller or equal to its first argument. The returned
function calls internally integrate
. Additional
arguments can be passed to the latter via the ... argument of the
returned function.
As explained in the details
section, the returned function has
the smooth density function, dFct
, as well as the inverse
function, qFct
, as attributes. Attribute call
contains
the matched call and range
contains the full range of the
mapped variable.
Since the density returned by dssden
can sometime
integrate to a value slightly different from 1 on its definition
domain, the actual integral is evaluated with integrate
and the returned density is renormalised. A lookup table of 101
regularly spaced quantiles and the corresponding probabilities is also
created and stored in the returned function closure. This lookup
table is used to speed up the computations performed by the returned
function which uses integrate
and not
pssden
. It is also used to speed up the
computations of the inverse function (returned as attribute
qFct
) which uses uniroot
and not
qssden
.
Christophe Pouzat christophe.pouzat@gmail.com
ssden
,
dssden
,
integrate
,
uniroot
,
mkGLMdf
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15  ## Not run:
require(STAR)
data(e060824spont)
DFA < subset(mkGLMdf(e060824spont,0.004,0,59),neuron==1)
DFA < within(DFA,i1 < isi(DFA,lag=1))
DFA < DFA[complete.cases(DFA),]
m2u1 < mkM2U(DFA,"lN.1",0,29)
m2ui < mkM2U(DFA,"i1",0,29,maxiter=200)
DFA < within(DFA,e1t < m2u1(lN.1))
DFA < within(DFA,i1t < m2ui(i1))
with(DFA,plot(ecdf(e1t[time>29]),pch="."))
abline(a=0,b=1,col=2,lty=2)
with(DFA,plot(ecdf(i1t[time>29]),pch="."))
abline(a=0,b=1,col=2,lty=2)
## End(Not run)

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