formatstring error when using tabularTextDatastore

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sani 2022-11-17

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1854163-formatstring-error-when-using-tabulartextdatastore

评论： Jeremy Hughes 2022-12-13

Hello all,
I am trying to read a large CSV file (~500GB) using tabularTextDatastore.
my command line is just one:
ds = tabularTextDatastore('filename.csv')
the error I'm getting is:
Error using tabularTextDatastore (line 147)
Output argument "formatString" (and maybe others) not assigned duting call to "matlab.io.internal.text.determineFormatString>convertDatatypeToFormatString".

could't find any material on this error online, can someone please advise?

thanks!

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Jeremy Hughes 2022-12-8

移动：Stephen23 2022-12-8

Without a sample file, anyone that might know how to help cannot reproduce the issue—this is probably why no one has responded. You'll have better luck getting help by adding an example file along with the code sample which reproduces the issue.

The code is there, but the file is an integral part of the reproduction. It doesn't have to be the exact file as long as you see the same issue. Try copying the first few lines of the file and see if that file still reproduces the issue.

I'd also suggest trying this same reproduction on another installation, on another machine. Sometimes these kinds of errors coming from MathWorks written code is due to files that are missing which should be available, or additional files on the path which are shadowing standard MathWorks functions. I'm not sure that's the case here, but I can't really try to reproduce it.

The second possibility is a bug in the existing code, which is being uncovered with this specific file, and we'd need to understand what's happening in order to fix it.

Without that file, they might be guessing at the content to try to reproduce it, but if they can't figure that out then they aren't likely to continue.

Stephen23 2022-12-8

编辑：Stephen23 2022-12-8

在 MATLAB Online 中打开

sample file.csv

What MATLAB version and OS are you using? The file works fine here:

ds = tabularTextDatastore('sample file.csv')

ds =

TabularTextDatastore with properties: Files: { '/users/mss.system.JLUjl3/sample file.csv' } Folders: { '/users/mss.system.JLUjl3' } FileEncoding: 'UTF-8' AlternateFileSystemRoots: {} VariableNamingRule: 'modify' ReadVariableNames: true VariableNames: {'BOARD', 'CHANNEL', 'TIMETAG' ... and 3 more} DatetimeLocale: en_US Text Format Properties: NumHeaderLines: 0 Delimiter: ';' RowDelimiter: '\r\n' TreatAsMissing: '' MissingValue: NaN Advanced Text Format Properties: TextscanFormats: {'%f', '%f', '%f' ... and 3 more} TextType: 'char' ExponentCharacters: 'eEdD' CommentStyle: '' Whitespace: ' \b\t' MultipleDelimitersAsOne: false Properties that control the table returned by preview, read, readall: SelectedVariableNames: {'BOARD', 'CHANNEL', 'TIMETAG' ... and 3 more} SelectedFormats: {'%f', '%f', '%f' ... and 3 more} ReadSize: 20000 rows OutputType: 'table' RowTimes: [] Write-specific Properties: SupportedOutputFormats: ["txt" "csv" "xlsx" "xls" "parquet" "parq"] DefaultOutputFormat: "txt"

sani 2022-12-8

I'm using MATLAB 2020a and windows 10 os

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Answer 1

Jeremy Hughes 2022-12-8

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1854163-formatstring-error-when-using-tabulartextdatastore#answer_1123707

编辑：Jeremy Hughes 2022-12-8

在 MATLAB Online 中打开

Turns out this was a bug in R2020a and is been fixed in R2020b. See: https://www.mathworks.com/support/bugreports/2263913

You can work around this with:

ds = tabularTextDatastore('sample file.csv','Delimiter',';','TextscanFormats',"%f%f%f%f%f%q")

or

ds = tabularTextDatastore('sample file.csv','Delimiter',';','TextscanFormats',"%f%f%f%f%f%x")

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Jeremy Hughes 2022-12-13

This looks like a separate issue with the format of the file not matching the expected format. You'll need to check the contents match on each row. If the rows aren't consistent with each other, then you might need to clean up the file to work with tabularTextDatastore.

If you're reading one file, then try readtable.

Jeremy Hughes 2022-12-13

The other alternative is to use all %q fields:

ds = tabularTextDatastore('sample file.csv','Delimiter',';','TextscanFormats',"%q%q%q%q%q%q")

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formatstring error when using tabularTextDatastore

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