R readr single col_types

Question

Is it possible within readr package to read in data and specify a single data type across all columns? Similar to base::read.table with colClasses = "character" or using the as.is argument.

Unless the task, data headers, file encoding, etc are well defined ahead of analysis I prefer to write my loaders without changing the datatypes and then process the schema later downstream. Always open to suggestion on how other folks think about things.

Answer 1

As of readr 0.2.2 we can do something like this to read a csv with all columns as character:

read_csv("path/to/file",col_types = cols(.default = col_character()))

Answer 2

Converting my comment to answer. No, this isn't built-in (at this point), the documentation of the col_types is quite clear about its capabilities, this isn't one of them. Given the way col_types works, implementing this would probably require a brand new argument since a feature is that a "short" col_types will be used to restrict the number of columns read.

However, you could write a wrapper:

read_table_asis = function(...) {
    n_cols = ncol(read_table(..., n_max = 1))
    read_table(..., col_types = paste(rep("c", n_cols), collapse = ""))
}