custom colClasses forces character during fread?
Nobody has claimed this yet.
Assessment
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Newbie friendliness
- 35/100
Research direction
Start by reproducing the fread example with colClasses=c(a='POSIXct'), then trace fread's '[09] Apply user overrides on column types' phase and its handling of the a column. Done means establishing whether the character-first conversion is intentional and resolving the reported type-conversion behavior with appropriate regression coverage if a change is needed.
Written by the indexing model from the issue text.
Description
Related Twitter thread:
https://twitter.com/jaredlander/status/1397586305022894082
I was surprised by the warning here:
data.table::fread('a\n1622058798', colClasses=c(a='POSIXct'))
a
1: 1622058798
Warning message:
Column 'a' was requested to be 'POSIXct' but fread encountered the following error:
character string is not in a standard unambiguous format
so the column has been left as type 'character'
Shouldn't as.POSIXct be applied to an integer (not a character?)
It seems we force any overrides to be read first as character:
[09] Apply user overrides on column types
After 1 type and 0 drop user overrides : C
I would have guessed a is read as integer (as it is if colClasses is not provided), and then as.POSIXct(1622058798) is run (which still wouldn't work)
I must be missing something -- is there a reason we apply the type override as character first in this case?
- Dominant language
- R
- Stars
- 3.9k
- Forks
- 1.1k
- Avg merge
- 14h 4m
- Merged PRs (30d)
- 4
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
More from Rdatatable/data.table
-
as.data.table() recurses without end on a survival::Surv object (or any data.frame carrying one) Open
Difficulty 2/5 1-3 hours Newbie friendliness 88/100
Rdatatable/data.table#7887 ·
-
consistency tests
Difficulty 2/5 1-3 hours Newbie friendliness 68/100
Rdatatable/data.table#7853 · 3 comments ·
-
internals
Difficulty 2/5 1-3 hours Newbie friendliness 65/100
Rdatatable/data.table#6938 · 1 comment ·
-
encoding fread
Difficulty 2/5 1-3 hours Newbie friendliness 65/100
Rdatatable/data.table#5179 · 8 comments ·
-
documentation programming
Difficulty 2/5 1-3 hours Newbie friendliness 68/100
Rdatatable/data.table#3199 · 3 comments ·
All issues in Rdatatable/data.table
Similar issues
-
Difficulty 2/5 1-3 hours Newbie friendliness 82/100
r-lib/pkgdepends#485 · 3 comments ·
-
Difficulty 1/5 Under an hour Newbie friendliness 92/100
-
beginners blocker
Difficulty 2/5 1-3 hours Newbie friendliness 78/100
-
enviPathR OpenBuild Error Build OK Build Warning policies-accepted pre-review precheck-passed
Difficulty 1/5 Under an hour Newbie friendliness 84/100
Bioconductor/BiocContributions#207 · 6 comments ·
-
Difficulty 2/5 1-3 hours Newbie friendliness 74/100
datacarpentry/semester-biology#1255 ·