One of NULL
, a cols
specification, or
a string. See vignette("column-types")
for more details. If NULL
, all column types will be imputed from the first 1000 rows
on the input. This is convenient (and fast), but not robust. If the
imputation fails, you'll need to supply the correct types yourself.
If a column specification created by cols
, it must contain
one column specification for each column. If you only want to read a
subset of the columns, use cols_only
.
Unlike other functions type_convert
does not allow character
specificatinos of col_types
.