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write_csv: Disable scientific notation for integers #765



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@zeehio zeehio commented Dec 16, 2017

Large integer numbers are not properly handled by write_csv as they are saved in scientific notation losing precision.

This PR is a followup of #679 much more simplified and hopefully closer to what @jimhester has in mind 馃槂

Thanks for your time reviewing it :-)

@zeehio zeehio force-pushed the write_csv_allow_long_int_without_scientific branch from 6e193da to 7106735 Compare December 16, 2017 12:13
@zeehio zeehio force-pushed the write_csv_allow_long_int_without_scientific branch from 7106735 to f032ab7 Compare December 17, 2017 15:28
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simecek commented Jan 6, 2018

I have run into a similar problem with Kaggle competition:

The input file train_2.csv contains Wikipedia traffic data, i.e. how many times the given page (in rows) was accessed on a given date (in columns). The read_csv function warned me that 37603th row was not parsed properly. That happened because of "1e+05" that parse_integer fails to parse as demonstrated below:

> parse_integer(c("1e05", "2", "3"))
Warning: 1 parsing failure.
row # A tibble: 1 x 4 col     row   col               expected actual expected   <int> <int>                  <chr>  <chr> actual 1     1    NA no trailing characters    e05
[1] NA  2  3
# A tibble: 1 x 4
    row   col               expected actual
  <int> <int>                  <chr>  <chr>
1     1    NA no trailing characters    e05 
> parse_double(c("1e05", "2", "3"))
[1] 1e+05 2e+00 3e+00

I am not sure how train_2.csv file was created and whether it is a problem of write_csv or not. However something similar is to be expected for any large file of integers just by a pure chance.

Inability to write data with write_csv and reading them back with read_csv (without specification of column types) might be challenging for beginners. I would suggest either accept this pull request or modify parse_integer to accept a scientific notation.

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zeehio commented Sep 30, 2018

This PR closes #845 :-)

@jimhester jimhester merged commit 213eb0e into tidyverse:master Nov 13, 2018
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Thanks for the PR and for your patience in getting it merged!

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3 participants