File g Open special format (ctrl-shift-O)

If the file to read is a binary file, or if it consists of more than two columns, or if the file has some lines to skip before the actual data begins, you can set the properties of the data set with this panel. If the file is so large that the processing of the graphs takes very long, you can also perform data reduction during the file read process.

Once set, the program remembers the special file settings while it is loaded. Every file that is opened will then be opened using the special format, unless it is again disabled with the disable button. Even when the program is ended and restarted the special format settings will remain, as they are stored in the SpecView.ini file. When you use a lot of different types of files, you can store the different settings in presets.

 The special format takes into account that a data file can consist of

• binary data

• more than two columns of data

• some initial lines with general parameters

• repeated data with several measurements in one file

• initial “measurement-parameter” lines preceding every repeated data set

• X can consist of a time format (data logging files, for example)

• too many data points (resolution)

For some examples of which files the program can read, take a look at the One column example, Two column example, 8 column example, Time format example, Repeated data example 1 and Repeated data example 2 files. There are presets stored in Spectrum Viewer to read these files.

To be able to display these types of files you get the choice to:

• Select the file format
  Text or binary.

• Set the X column
  The column you would like to end up in the X axis (0 has the same effect as opening a file with one column only, see basic operations).

• Set the Y column
  The column you would like to end up in the Y axis. 0 opens every column in a separate data set.

• Define if the X column is in time format
  When data logging, the X value can be a time format. The problem with this format is, is that it consists of several (usually 2 or 3) columns of digits, separated by a ":". When specifying that the X column represents a time, you also have to specify the time format (H:M, M:S or H:M:S). The program then calculates the number of minutes, or the number of seconds, for the X value. Keep in mind, when specifying the Y column, that the program still will see the time columns as individual (two or three) columns.

• Define if the data file consists of repeated data

• Define if this repeated data belongs to one measurement or to several measurements

• Define if you want Data Reduction
  If the number of data points in a file is so large that processing afterwards becomes very slow, you can reduce the number of data points in several ways. 
  1 - You can limit the number of data points in a data set: 
       all the data points which are read after the limit is reached are discarded. 
  2 - You can skip a given number of data points at the beginning of each file. 
  3 -  You can discard a given number of data points at the end of each file. 
  4 -  You can automatically downsample a data set after it is read from the file.

• Auto scale
  Automatically set the gain or offset directly after reading the file. Opposed to setting the gain on the axis itself, this will alter the data.

• Skip file contents
  "Skip initial lines" defines the number of (text)lines to be skipped at the beginning of the file. "Skip repeated lines" defines the number of lines to be skipped at the start of each “window” of repeated data, when applicable.

• Set the default file names
  The “default file spec” setting determines the default file name that will already be filled in in the open file dialog box. If all your file names end on .dat, make the default file spec “*.dat”, and the dialog box will only display the files actually ending on .dat in the selected folder. Then you can open them all in one go by just pressing ctrl-a. 
  If you have several types of data files that end on different extensions, you can use the “default file extensions” setting. For example, if your measure files all end on “.meas.txt” or “.spec.txt” you could set the default extensions line to “*.meas.txt;*.spec.txt” and these extensions will appear in the “files of type” select box in the open file dialog box. Thus you can switch easily between the files you want to display in the dialog box.

• Define a plug-in path name
  If a data file is so complicated that even Spectrum Viewer can't read it, you can write your own file converter plugin. If a plugin path is defined, all other settings (except the default file names and extensions) will be ignored.

• Set the default axis names and graph title
  When a file is opened with a special format setting, the axis names and graph title will be changed according to this preset. When the fields are empty the axis names will be left untouched..