Constructs a mapper
that aggregates elements of exp(state), with optional non-negative weighting,
and then takes the log(), so it can be used e.g.
for \(v_k=\log[\sum_{i\in I_k} w_i \exp(u_i)]\)
and \(v_k=\log[\sum_{i\in I_k} w_i \exp(u_i) / \sum_{i\in I_k} w_i]\)
calculations. Relies on the input handling methods for bru_mapper_aggregate,
but also allows the weights to be supplied on a logarithmic scale as log_weights.
To avoid numerical overflow, it uses the common method of internally
shifting the state blockwise;
\(v_k=s_k+\log[\sum_{i\in I_k} \exp(u_i + \log(w_i)- s_k)]\),
where \(s_k=\max_{i\in I_k} u_i + \log(w_i)\) is the shift for block \(k\).
bru_mapper_logsumexp(rescale = FALSE, n_block = NULL)# S3 method for bru_mapper_logsumexp
ibm_jacobian(mapper, input, state = NULL, ...)
# S3 method for bru_mapper_logsumexp
ibm_eval(mapper, input, state = NULL, log = TRUE, ..., sub_lin = NULL)
logical; For bru_mapper_aggregate and bru_mapper_logsumexp,
specifies if the blockwise sums should be normalised by the blockwise weight
sums or not:
FALSE: (default) Straight weighted sum, no rescaling.
TRUE: Divide by the sum of the weight values within each block.
This is useful for integration averages, when the given weights are plain
integration weights. If the weights are NULL or all ones, this is
the same as dividing by the number of entries in each block.
Predetermined number of output blocks. If NULL, overrides
the maximum block index in the inputs.
A mapper S3 object, inheriting from bru_mapper.
Data input for the mapper.
A vector of latent state values for the mapping,
of length ibm_n(mapper, inla_f = FALSE)
Arguments passed on to other methods
logical; control log output. Default TRUE, see the ibm_eval() details
for logsumexp mappers.
Internal, optional pre-computed sub-mapper information
ibm_eval(bru_mapper_logsumexp): When log is TRUE (default), ibm_eval() for logsumexp returns
the log-sum-weight-exp value. If FALSE, the sum-weight-exp value is returned.
For bru_mapper_logsumexp, input should be a list with elements block
and weights. block
should be a vector of the same length as the state, or NULL, with NULL
equivalent to all-1.
If weights is NULL, it's interpreted as all-1.
bru_mapper, bru_mapper_generics
Other mappers:
bru_get_mapper(),
bru_mapper(),
bru_mapper.fm_mesh_1d(),
bru_mapper.fm_mesh_2d(),
bru_mapper_aggregate(),
bru_mapper_collect(),
bru_mapper_const(),
bru_mapper_factor(),
bru_mapper_generics,
bru_mapper_harmonics(),
bru_mapper_index(),
bru_mapper_linear(),
bru_mapper_marginal(),
bru_mapper_matrix(),
bru_mapper_mesh_B(),
bru_mapper_multi(),
bru_mapper_pipe(),
bru_mapper_scale(),
bru_mapper_shift(),
bru_mapper_taylor()
m <- bru_mapper_logsumexp()
ibm_eval2(m, list(block = c(1, 2, 1, 2), weights = 1:4), 11:14)
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