read_csv() incorrectly reads character vectors if all strings begin with "Inf" (e.g. "Inform")

[sdevine188]

Thank you for the excellent readr package! I think I'm seeing unexpected behavior from read_csv() though. When trying to read a tibble containing a character vector of strings that all begin with "Inf" (e.g. "Inform", "Information"), read_csv() incorrectly reads it as a numeric Inf, instead of correctly reading it as a string. The base read.csv() correctly reads it as a string though. If the character vector contains at least one string that does not begin with "Inf" however (e.g. "Indigo"), then read_csv() will correctly read the vector as a string. Read_csv() will also correctly read the vector as a string if the col_types argument specifies it as a character vector, but that requires manual checks/edits.

It seems problematic to have to continually check all character vectors first and then manually specify col_types if all the strings happen to begin with "Inf". Is it possible to please update read_csv() to handle these kind of vectors in the same way as read.csv()?

Thanks very much, and apologies if I'm just missing something. (also posted on Stack Overflow: https://stackoverflow.com/questions/69680431/r-readrread-csv-incorrectly-reads-character-vectors-if-all-strings-begin-with)

suppressPackageStartupMessages(library(tidyverse))

#################################################

# save tibble with character vector containing only strings that begin with "Inf"
test_1 <- tibble(x = c("Inform", "Information"))
test_1 %>% glimpse()
#> Rows: 2
#> Columns: 1
#> $ x <chr> "Inform", "Information"
test_1 %>% write_csv(file = "test_1.csv")

# read_csv() seems to convert the strings into numeric Inf because they all begin with "Inf"
# however, if col_types is manually specified as col_character, then read_csv() correctly reads the vector as a string
read_csv(file = "test_1.csv")
#> Rows: 2 Columns: 1
#> -- Column specification --------------------------------------------------------
#> Delimiter: ","
#> dbl (1): x
#> 
#> 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: 2 x 1
#>       x
#>   <dbl>
#> 1   Inf
#> 2   Inf
read_csv(file = "test_1.csv", lazy = FALSE)
#> Rows: 2 Columns: 1
#> -- Column specification --------------------------------------------------------
#> Delimiter: ","
#> dbl (1): x
#> 
#> 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: 2 x 1
#>       x
#>   <dbl>
#> 1   Inf
#> 2   Inf
read_csv(file = "test_1.csv", col_types = cols(x = col_character()))
#> # A tibble: 2 x 1
#>   x          
#>   <chr>      
#> 1 Inform     
#> 2 Information

# read.csv() correctly reads the vector as a string
read.csv(file = "test_1.csv") %>% glimpse()
#> Rows: 2
#> Columns: 1
#> $ x <chr> "Inform", "Information"

# read_csv() correctly reads similar character vectors if they contain at least one string that does not begin with "Inf"
test_2 <- tibble(x = c("Inform", "Indigo", "Information")) %>% write_csv(file = "test_2.csv")
read_csv(file = "test_2.csv") %>% glimpse()
#> Rows: 3 Columns: 1
#> -- Column specification --------------------------------------------------------
#> Delimiter: ","
#> chr (1): x
#> 
#> 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.
#> Rows: 3
#> Columns: 1
#> $ x <chr> "Inform", "Indigo", "Information"

#################################################

# get version info
packageVersion("tidyverse")
#> [1] '1.3.1'
version
#>                _                           
#> platform       x86_64-w64-mingw32          
#> arch           x86_64                      
#> os             mingw32                     
#> system         x86_64, mingw32             
#> status                                     
#> major          4                           
#> minor          1.1                         
#> year           2021                        
#> month          08                          
#> day            10                          
#> svn rev        80725                       
#> language       R                           
#> version.string R version 4.1.1 (2021-08-10)
#> nickname       Kick Things

^{Created on 2021-10-22 by the reprex package (v2.0.1)}

[jimhester]

Thank you for opening the issue and for supplying a reproducible example, it is a big help!

This should be fixed in the next release of vroom.