Error in get_solution() in case there is only one variable

[saurav2608]

library(tidyverse)
#> -- Attaching packages ---------- tidyverse 1.2.1 --
#> v ggplot2 2.2.1 v purrr 0.2.4
#> v tibble 1.4.2 v dplyr 0.7.4
#> v tidyr 0.8.0 v stringr 1.3.0
#> v readr 1.1.1 v forcats 0.3.0
#> -- Conflicts ------------- tidyverse_conflicts() --
#> x dplyr::filter() masks stats::filter()
#> x dplyr::lag() masks stats::lag()
library(ompr)
library(ompr.roi)
library(ROI.plugin.glpk)
n <- 1; W <- 2
v <- runif(n);w <- runif(n)
model <- MIPModel() %>%
add_variable(x[i], i = 1:n, type = "binary") %>%
set_objective(sum_expr(v[i] * x[i], i = 1:n)) %>%
add_constraint(sum_expr(w[i] * x[i], i = 1:n) <= W)
result <- solve_model(model, with_ROI(solver = "glpk", verbose = FALSE))
solution <- get_solution(result, x[i])
#> Warning in seq_len(ncol(var_index)): first element used of 'length.out'
#> argument
#> Error in seq_len(ncol(var_index)): argument must be coercible to non-negative integer

[saurav2608]

Located the issue in the definition of extract_solution(). Return type of var_index <- do.call(rbind, regmatches(solution_names, rexp_c)) is not a matrix in case there is only one element in regmatches(solution_names, rexp_c). Thus the line result_df <- as.data.frame(var_index[, seq_len(ncol(var_index))[-1]]) trips as ncol is not define for non-matrix

[dirkschumacher]

Ah interesting. Thanks a lot!

[dirkschumacher]

Seems to be a bug in dirkschumacher/ompr.roi#19

[dirkschumacher]

Thanks a lot. drop = TRUE striked again.

[saurav2608]

Oh you are quick. I was preparing a PR. I started using your package recently. It is very good.

[dirkschumacher]

Thanks for reporting the bug. I am slowly restarting my OS work again after a temoral leave, so I thought this is a good start ;)