I am trying to use textscan in MATLAB to read in mixed format data from a .csv file. I am currently running into a problem that there are a number of nonvisible characters which are getting read in as a string when I am not expecting them. I believe if I set this character as a delimiter or whitespace it will solve my text scanning issue.
My main problem at the moment is that I don't know what character it is to be able to identify it. I have used isstrprop to determine that it is a control character. I guessed that it was the NUL character, so I tried adding \0 to the delimiter set for textscan. Unfortunately MATLAB does not recognize that as a valid \ constant.
Below is one line of the data file, copied from Notepad. The characters preceding each of the commas are the ones in question. The following line is the command I used in MATLAB to read it.
1 ,T,171215,173201,21.982413N,159.342881W,150 ,0 ,0 ,3D,SPS ,2.7 ,2.5 ,1.0 ,
C = textscan(fid,'%d%s%d%d%s%s%d%d%d%s%s%f%f%f%s','delimiter',',','headerlines',1,'MultipleDelimsAsOne',1)
Also, for what it's worth, using deblank on the string of characters that is read in does remove them. However, I only know how to apply this after the textscan, so the characters still throw off the parsing.
How can I identify this character and set it to be ignored by textscan?
Related
So I have a dataset which I want to export to csv with pipe as separator and no escape character.
That dataset contains in fact 4 source columns, 3 regular ones (just text) and one variable one.
That last column holds another subset of values that are also separated with a pipe.
Purpose is that the export looks like this, where the values are coming from my 4th field.
COL1|COL2|COL3|VAL1|VAL2|VAL3|....
The number of values can be different for each record but.
When I set the csv export separator to ";", I get this result which is expected
COL1;COL2;COL3;VAL1|VAL2|VAL3|....
However setting it to "|", it throws the error DF-CSVWriter-InvalidEscapeSetting.
Most likely because it detected the separator character in my 4th field and then enforces that an escape character needs to be set.
Which is a logical thing in most case but in my case I would like him to ignore this and just export as-is.
Any way how I can work around this, perhaps with a different approach or some additional settings?
Split & flatten produces extra rows but that's not what I want.
Regards,
Sven Peeters
As you have the same characters in the column value same as your delimiter character, with no escape character in your dataset will throw an error.
You have to change the delimiter character to a different character or add a Quote character and Escape character to Double quote(").
Downloaded file:
I'm trying to accomplish following task in Octave:
Read filename from text file
Search for this file in particular location on hard drive
My script works for most files, but for certain files containing unicode characters I'm unable to match the filename from textfile with filename as it appears in the file system.
Filenames in textfile are in UTF-8 encoding and I read them in Octave with function fgetl().
Filenames from file system are obtained via function readdir(). I'm on Windows, NTFS file system.
For example, one problematic filename contains character "Č".
When printed out in Octave console, the characters appear exactly the same. However, a HEX viewer reveals that the characters are not actually the same. In the first case the character is encoded as 0x010C, in the second case as 0x0043 + 0x030C. Comparing both of them via strcmp() fails, of course.
What I tried to do is to omitt all non-ASCII characters from the filename and then compare them. But this didn't work, probably because in the second variant the first part of the character (0x0043) is actually ASCII.
Now I'm looking for some way of converting one format to another to be able to compare them. Any ideas?
EDIT:
As I discovered later, the character Č in the filename on Windows is actually written as C+ˇ, which is just another way you can write that character. So the difference probably insn't in encoding standard, but in 2 different ways to achieve 1 visible character (glyph).
This question basically then changes to a task of matching characters written "at once" and corresponding pair of letter+combining character.
I have a source file that has text columns which end with a "\" and I have specified "^" as the column delimiter.
I have the file format for this specified use - ESCAPE = 'NONE', but rows with "\^" are causing premature end-of-line errors - assuming SF is not interpreting the "\^" as a column delimiter - therefore the column count is off.
I have changed the file format to use something else for ESCAPE but get the same message. The offending rows have the right number of columns and a text column containing "\", that is not the last character in the column, imports correctly.
The values are exported from SQL Server.
Is this an escape character problem or am I overlooking something else? I am new to SF.
I was seeing this same issue. Nomatter what I used as an escape character, when it showed up in my file next to a " at the end of a string it started causing trouble.
I switched my delimiter to \u0001 which is a special "start of header" character that very rarely shows up, especially at the end of strings.
I wouldn't say this was an ideal option for us, but it worked and is something you might want to try.
The file format I have is sort of like csv and looks like this (abinitio .dat file of some sort):
1,apple,10.00,\n
2,banana,12.35,\n
3,orange,9.23,\n
The commas are actually "Start of Header" 0x01 byte characters, but I will use commas for simplicity. I can easily read the above sample by reading the file as a string RDD with a custom line split ,\n and then passing that into spark.read.csv. I am currently splitting lines by ,\n because there may be newlines in the data and I thought that those two characters were unique for each record. However a problem occurs when there are newline characters at the start of text fields. For example:
1,one \n apple,10.00,\n
2,two banana,12.35,\n
3,\n three orange,9.23,\n
My current code is able to ignore the newline in record 1 but picks up the ,\n after the 3 and splits the 3 lines into 4. How can I reliably read in this format?
My current ideas are:
Check that there are the right number of , column delimiters before allowing a split. I am not sure how to implement this, is it possible to do a regex look-back when spark sees a ,\n and check for the correct number of delimiters?
Try to coerce the file into some other format besides CSV
Make my own InputFormatClass, although I am not sure what this entails.
I am exporting some Access tables to txt files and there are a lot of problems with the txt file. One of those problems being line breaks not visible in the txt file itself. If I copy a line with a line break into Notepad++ from Notepad, it'll break into 2 lines.
So I believe this may be a code format problem, but I can't find the proper one to resolve this. I'm currently exporting to the default Western European, but should I export tot UTF, Unicode, ASCII or something else?
When exporting from MS Access (or VB/VBA in general), make sure you're using vbCrLf constant (Carriage Return plus Line Feed) for line breaks. That constant corresponds to HEX values 0D 0A.
In Windows, it is a convention to use the above 2 characters together as line breaks, while in many other platforms, such as Unix/Linux/MacOS/etc. typically just 0A is used.
That brings up an issue: Notepad, the standard Windows text file viewer, cannot deal with 0A alone and does not treat such symbols as line breaks. More advanced editors, such as Notepad++ or UltraEdit, display such files correctly, though.
The CSV export function in Microsoft Office applications (Excel, Access) terminate a data row with CR+LF and write for a line break within a data value (multi-line string) just LF into the file. (I think just CR was written into the CSV file for a line break in older versions of Office before Office 2007.)
Most text editors detect those LF without CR (respectively CR without LF) and convert them to CR+LF on loading the CSV file which results on viewing of the CSV file in text editor in supposed wrong CSV lines as number of data values is not correct on data rows with data values containing a line break.
However, newline characters within a double quoted value in a CSV file are correct according to CSV specification as described in Wikipedia article about Comma-separated values.
But most applications with support on import from CSV file do not support CSV files with newline characters within a double quoted value and therefore some data values are imported wrong. Also regular expression replaces can't be done on a CSV file with newline characters within a data value because the number of separator character is not constant on all lines.
UltraEdit has for editing such CSV files with only LF (or CR) for a line break within a data value a special configuration setting. At Advanced - Configuration - File Handling - DOS/Unix/Mac Handling the option Never prompt to convert files to DOS format or Prompt to convert if file is not DOS format with clicking on button No if this prompt is displayed must be selected and additionally Only recognize DOS terminated lines (CR/LF) as new lines for editing must be enabled.
The CSV file with CR+LF for end of data row and only LF (or CR) for a line-break within a data value is loaded with those settings in UltraEdit with number of lines equal the number of data rows. And the line-feeds without carriage return (respectively the carriage returns without line-feed) in the CSV file are displayed as character in the lines with a small rectangle as no font has a glyph for a carriage return or line-feed defined because they are whitespace characters with no width. A Perl regular expression find searching for \r(?!\n)|\n(?<!\r) can be used now to find those line breaks within data values and replace them with something different like a space character or remove them.
Which character encoding (ASCII, ANSI, Unicode (UTF-16), UTF-8) to use on export depends on which characters can exist in string values. A Unicode encoding is necessary if string values can have also characters not included in local code page.