R/201_reductions_dgp2dcp_canonicalizers_sum_canon.R

In CVXR: Disciplined Convex Optimization

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## DO NOT EDIT THIS FILE!! EDIT THE SOURCE INSTEAD: rsrc_tree/reductions/dgp2dcp/canonicalizers/sum_canon.R
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## CVXPY SOURCE: reductions/dgp2dcp/canonicalizers/sum_canon.py
## DGP canonicalizer for SumEntries: sum -> explicit_sum -> add_canon

.dgp_sum_canon <- function(expr, args) {
  X <- args[[1L]]

  if (is.null(expr@axis)) {
    ## Sum all elements
    summation <- .dgp_explicit_sum(X)
    result <- .dgp_add_canon(summation, summation@args)
    canon <- result[[1L]]
    return(list(reshape_expr(canon, expr@shape), list()))
  }

  ## Axis-wise sum
  if (expr@axis == 2L) {
    X <- t(X)
  }

  row_canons <- list()
  for (i in seq_len(X@shape[1L])) {
    summation <- .dgp_explicit_sum(X[i, ])
    result <- .dgp_add_canon(summation, summation@args)
    row_canons <- c(row_canons, list(result[[1L]]))
  }
  canon <- do.call(hstack, row_canons)
  list(reshape_expr(canon, expr@shape), list())
}