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formatstring error when using tabularTextDatastore

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sani
sani am 17 Nov. 2022
Kommentiert: Jeremy Hughes am 13 Dez. 2022

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!

  7 Kommentare
Stephen23
Stephen23 am 8 Dez. 2022
Bearbeitet: Stephen23 am 8 Dez. 2022
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
sani am 8 Dez. 2022
I'm using MATLAB 2020a and windows 10 os

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Jeremy Hughes
Jeremy Hughes am 8 Dez. 2022
Bearbeitet: Jeremy Hughes am 8 Dez. 2022
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")
  5 Kommentare
Jeremy Hughes
Jeremy Hughes am 13 Dez. 2022
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
Jeremy Hughes am 13 Dez. 2022
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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