Add pivot_longer() about poorman HOT 1 CLOSED

pivot_longer = 
  function(
    data,
    cols,
    names_to = "name",
    names_prefix = NULL,
    # names_sep = NULL,
    # names_pattern = NULL,
    # names_ptypes = list(),
    # names_transform = list(),
    # names_repair = "check_unique",
    values_to = "value",
    # values_drop_na = FALSE,
    # values_ptypes = list(),
    # values_transform = list(),
    ...
  ){
    cols = deparse(substitute(cols))
    if (grepl("^!|^-", cols)) {
      cols = setdiff(names(data), gsub("^!|^-", "", cols))
    }
    ocols = setdiff(names(data), cols)
    stacked_data = stack(data[, cols])[, 2:1]
    ret = cbind(data[, ocols], setNames(stacked_data, c(names_to, values_to)))
    if (!is.null(names_prefix)) {
      ret[[names_to]] = gsub(paste0("^", names_prefix), "", ret[[names_to]])
    }
    ret = ret[order(ret[, ocols[1]]), ]
    rownames(ret) = 1:nrow(ret)
    ret
  }

#
## First example from ?tidy::pivot_longer
#

data('relig_income', package = 'tidyr')

## This version
relig_income |>
  pivot_longer(!religion, names_to = "income", values_to = "count") |>
  head(10)
#>    religion             income count
#> 1  Agnostic              <$10k    27
#> 2  Agnostic            $10-20k    34
#> 3  Agnostic            $20-30k    60
#> 4  Agnostic            $30-40k    81
#> 5  Agnostic            $40-50k    76
#> 6  Agnostic            $50-75k   137
#> 7  Agnostic           $75-100k   122
#> 8  Agnostic          $100-150k   109
#> 9  Agnostic              >150k    84
#> 10 Agnostic Don't know/refused    96

## tidyr version
relig_income |>
  tidyr::pivot_longer(!religion, names_to = "income", values_to = "count") |>
  data.frame() |> head(10)
#>    religion             income count
#> 1  Agnostic              <$10k    27
#> 2  Agnostic            $10-20k    34
#> 3  Agnostic            $20-30k    60
#> 4  Agnostic            $30-40k    81
#> 5  Agnostic            $40-50k    76
#> 6  Agnostic            $50-75k   137
#> 7  Agnostic           $75-100k   122
#> 8  Agnostic          $100-150k   109
#> 9  Agnostic              >150k    84
#> 10 Agnostic Don't know/refused    96

#
## Contrived names_prefix useage
#

## This version
relig_income[, c(1, 3:9)] |>
  pivot_longer(!religion, names_to = "income", values_to = "count", names_prefix = "\\$") |>
  head(10)
#>    religion   income count
#> 1  Agnostic   10-20k    34
#> 2  Agnostic   20-30k    60
#> 3  Agnostic   30-40k    81
#> 4  Agnostic   40-50k    76
#> 5  Agnostic   50-75k   137
#> 6  Agnostic  75-100k   122
#> 7  Agnostic 100-150k   109
#> 8   Atheist   10-20k    27
#> 9   Atheist   20-30k    37
#> 10  Atheist   30-40k    52

## tidyr version
relig_income[, c(1, 3:9)] |>
  tidyr::pivot_longer(!religion, names_to = "income", values_to = "count", names_prefix = "\\$") |>
  data.frame() |> head(10)
#>    religion   income count
#> 1  Agnostic   10-20k    34
#> 2  Agnostic   20-30k    60
#> 3  Agnostic   30-40k    81
#> 4  Agnostic   40-50k    76
#> 5  Agnostic   50-75k   137
#> 6  Agnostic  75-100k   122
#> 7  Agnostic 100-150k   109
#> 8   Atheist   10-20k    27
#> 9   Atheist   20-30k    37
#> 10  Atheist   30-40k    52