This function computes the Likelihood Ratios for the gene sets under scrutiny, as well as estimations of genes dynamics inside those gene sets through mixed models.
TcGSA.LR(
expr,
gmt,
design,
subject_name = "Patient_ID",
time_name = "TimePoint",
crossedRandom = FALSE,
covariates_fixed = "",
time_covariates = "",
time_func = "linear",
group_name = "",
separateSubjects = FALSE,
minGSsize = 10,
maxGSsize = 500
)# S3 method for TcGSA
print(x, ...)
a matrix or dataframe of gene expression. Its dimension are \(n\)x\(p\), with the \(p\) samples in column and the \(n\) genes in row.
a gmt object containing the gene sets definition. See
GSA.read.gmt and definition on
www.software.broadinstitute.org.
a matrix or dataframe containing the experimental variables that used in the model,
namely subject_name, time_name, and covariates_fixed
and time_covariates if applicable. Its dimension are \(p\)x\(m\)
and its row are is in the same order as the columns of expr.
the name of the factor variable from design that contains the information on
the repetition units used in the mixed model, such as the patient identifiers for instance.
Default is 'Patient_ID'. See Details.
the name of a numeric variable from design that contains
the information on the time replicates (the time points at which gene
expression was measured). Default is 'TimePoint'. See Details.
logical flag indicating whether the random effects of the subjects and of the time points
should be modeled as one crossed random effect or as two separated random effects.
Default is FALSE. See details.
a character vector with the names of numeric or factor variables from the design
matrix that should appear as fixed effects in the model. See details.
Default is "", which corresponds to no covariates in the model.
a character vector with the names of numeric or factor variables from the design
matrix that should appear as fixed effects interaction with the time_name
variable in the model. See details. Default is "", which corresponds
to no covariates in the model.
the form of the time trend. Can be either one of "linear",
"cubic", "splines" or specified by the user, or the column name of
a factor variable from design. If specified by the user,
it must be as an expression using only names of variables from the design matrix
with only the three following operators: +, *, / .
The "splines" form corresponds to the natural cubic B-splines
(see also ns). If there are only a few timepoints,
a "linear" form should be sufficient. Otherwise, the "cubic" form is
more parsimonious than the "splines" form, and should be sufficiently flexible.
If the column name of a factor variable from design is supplied,
then time is considered as discrete in the analysis.
If the user specify a formula using column names from design, both factor and numeric
variables can be used.
in the case of several treatment groups, the name of a factor variable
from the design matrix. It indicates to which treatment group each sample
belongs to. Default is "", which means that there is only one
treatment group. See Details.
logical flag indicating that the analysis identifies
gene sets that discriminates patients rather than gene sets than have a
significant trend over time. Default is FALSE. See Details.
the minimum number of genes in a gene set. If there are
less genes than this number in one of the gene sets under scrutiny, the
Likelihood Ratio of this gene set is not computed (the mixed model are not
fitted). Default is 10 genes as the minimum.
the maximum number of genes in a gene set. If there are
more genes than this number in one of the gene sets under scrutiny, the
Likelihood Ratio of this gene set is not computed (the mixed model are not
fitted). This is to avoid very long computation times. Default is
500 genes as the maximum.
an object of class 'TcGSA'.
further arguments passed to or from other methods.
TcGSA.LR returns a tcgsa object, which is a list with
the 5 following elements:
fit a data frame that contains the 3 following variables:
LR: the likelihood ratio between the model under the
null hypothesis and the model under the alternative hypothesis.
CVG_H0: convergence status of the model under the null hypothesis.
CVG_H1: convergence status of the model under the alternative
hypothesis.
time_func: a character string passing along the value of the
time_func argument used in the call.
GeneSets_gmt: a gmt object passing along the value of the
gmt argument used in the call.
group.var: a factor passing along the group_name variable
from the design matrix.
separateSubjects: a logical flag passing along the value of the
separateSubjects argument used in the call.
Estimations: a list of 3 dimensions arrays. Each element of the
list (i.e. each array) corresponds to the estimations of gene expression
dynamics for each of the gene sets under scrutiny (obtained from mixed
models). The first dimension of those arrays is the genes included in the
concerned gene set, the second dimension is the Patient_ID, and the
third dimension is the TimePoint. The values inside those arrays are
estimated gene expressions.
time_DF: the degree of freedom of the natural splines functions
This Time-course Gene Set Analysis aims at identifying gene sets that are not
stable over time, either homogeneously or heterogeneously (see Hejblum
et al, 2012)in terms of their probes. And when the argument
separateSubjects is TRUE, instead of identifying gene sets that
have a significant trend over time, TcGSA identifies gene sets that
have significantly different trends over time depending on Subjects.
Hejblum BP, Skinner J, Thiebaut R, (2015) Time-Course Gene Set Analysis for Longitudinal Gene Expression Data. PLOS Comput. Biol. 11(6):e1004310. doi: 10.1371/journal.pcbi.1004310
summary.TcGSA, plot.TcGSA,
and TcGSA.LR.parallel for an implementation using
parallel computing
# NOT RUN {
if(interactive()){
data(data_simu_TcGSA)
tcgsa_sim_1grp <- TcGSA.LR(expr=expr_1grp, gmt=gmt_sim, design=design,
subject_name="Patient_ID", time_name="TimePoint",
time_func="linear", crossedRandom=FALSE)
tcgsa_sim_1grp
summary(tcgsa_sim_1grp)
plot(x=tcgsa_sim_1grp, expr=expr_1grp,
Subject_ID=design$Patient_ID, TimePoint=design$TimePoint,
baseline=1,
B=100,
time_unit="H"
)
tcgsa_sim_2grp <- TcGSA.LR(expr=expr_2grp, gmt=gmt_sim, design=design,
subject_name="Patient_ID", time_name="TimePoint",
time_func="linear", crossedRandom=FALSE,
group_name="group.var")
tcgsa_sim_2grp
}
# }
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