read_delim throws the 'Could not guess the delimiter' error if there is only one column or data is quoted with double quotes.

[hidekoji]

read_delim throws the 'Could not guess the delimiter' error if there is only one column and the delim argument is not explicitly set.

readr::read_delim("a
2022-01-01")
#> Error: Could not guess the delimiter.
#> 
#> Use `vroom(delim =)` to specify one explicitly.

^{Created on 2023-01-13 with reprex v2.0.2}

but if you explicitly specify the delim as "," it works.

readr::read_delim("a
2022-01-01", delim = ",")
#> Rows: 1 Columns: 1
#> ── Column specification ────────────────────────────────────────────────────────
#> Delimiter: ","
#> date (1): a
#> 
#> ℹ Use `spec()` to retrieve the full column specification for this data.
#> ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
#> # A tibble: 1 × 1
#>   a         
#>   <date>    
#> 1 2022-01-01

^{Created on 2023-01-13 with reprex v2.0.2}

readr version is 2.1.3

[hidekoji]

sessionInfo()
#> R version 4.2.1 (2022-06-23)
#> Platform: x86_64-apple-darwin17.0 (64-bit)
#> Running under: macOS Big Sur ... 10.16
#> 
#> Matrix products: default
#> BLAS:   /Library/Frameworks/R.framework/Versions/4.2/Resources/lib/libRblas.0.dylib
#> LAPACK: /Library/Frameworks/R.framework/Versions/4.2/Resources/lib/libRlapack.dylib
#> 
#> locale:
#> [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
#> 
#> attached base packages:
#> [1] stats     graphics  grDevices utils     datasets  methods   base     
#> 
#> loaded via a namespace (and not attached):
#>  [1] withr_2.5.0     digest_0.6.31   lifecycle_1.0.3 magrittr_2.0.3 
#>  [5] reprex_2.0.2    evaluate_0.19   highr_0.10      stringi_1.7.8  
#>  [9] rlang_1.0.6     cli_3.5.0       rstudioapi_0.14 fs_1.5.2       
#> [13] vctrs_0.5.1     rmarkdown_2.19  tools_4.2.1     stringr_1.5.0  
#> [17] glue_1.6.2      xfun_0.36       yaml_2.3.6      fastmap_1.1.0  
#> [21] compiler_4.2.1  htmltools_0.5.4 knitr_1.41

^{Created on 2023-01-13 with reprex v2.0.2}

[hidekoji]

Also, if the data is quoted with double quotes, it cannot detect delimiter even with the quote argument.

df <- readr::read_delim('"Date","WWDC Page Access"
"2015-07-01",186
"2015-07-02",161', quote = '"')
#> Error: Could not guess the delimiter.
#> 
#> Use `vroom(delim =)` to specify one explicitly.

^{Created on 2023-01-27 with reprex v2.0.2}

If it's not quoted with double quotes, it can detect a delimiter.

df <- readr::read_delim('Date,WWDC Page Access
2015-07-01,186
2015-07-02,161')
#> Rows: 2 Columns: 2
#> ── Column specification ────────────────────────────────────────────────────────
#> Delimiter: ","
#> dbl  (1): WWDC Page Access
#> date (1): Date
#> 
#> ℹ Use `spec()` to retrieve the full column specification for this data.
#> ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.

^{Created on 2023-01-27 with reprex v2.0.2}

[hadley]

I think this is a reasonable error — it's hard for readr to know if it's a single column of data or it's failed to figure out the delimiter.