How to log the contents of a dataframe?

[mikekaminsky]

Hi! Sorry if this is a dumb question, but I want to do something like:

dropped_rows <- grouped_clean_data %>% select(date, idx, n_days) %>% filter(n_days <7)
if (nrow(dropped_rows) > 0){
  log_warn("Dropping the following weeks due to incomplete data:")
  log_warn("{dropped_rows}")
}

But this ... doesn't work. What's the recommend way to achieve something like this?

[daroczig]

You can transform your data frame to strings before passing to logger, or do that automatically eg via formatter_pander from #22 -- will try to merge that later this week.

[daroczig]

The above PR was merged, so now you should be able to use formatter_pander to easily log data frames.

[klin333]

what about something like this?

formatter_format_paste <- function (..., 
                                    .logcall = sys.call(), .topcall = sys.call(-1), 
                                    .topenv = parent.frame()) {
  
  # format items using generic function and collapse with newline
  args <- unlist(lapply(list(...), function(x) {
    if (is.data.frame(x)) {
      s <- paste(format(tibble::as_tibble(x)), collapse = '\n')
    } else{
      s <- paste(format(x), collapse = '\n')
    }
    s
  }))
  
  # insert ' ' if previous item does not end with '\n'
  for (i in utils::head(seq_len(length(args)), -1)) {
    s <- args[i]
    n <- nchar(s)
    if (substr(s, n, n) != '\n') {
      args[i] <- paste0(s, ' ')
    }
  }
  
  paste(args, collapse = "")
}

log_formatter(formatter_format_paste)

> log_info(datasets::cars, '\n', 'abc')
INFO [2023-07-11 10:09:51] # A tibble: 50 x 2
   speed  dist
   <dbl> <dbl>
 1     4     2
 2     4    10
 3     7     4
 4     7    22
 5     8    16
 6     9    10
 7    10    18
 8    10    26
 9    10    34
10    11    17
# ... with 40 more rows
# i Use `print(n = ...)` to see more rows 
abc