Input and Output Functions

ASCII Files

• IXTdataset_1d objects may be stored in ASCII files.
• These files may contain x and y data or x, y, error data in a 2 or 3 column format.
• Column 1 will be x values, column 2 will be y values and if available column 3 will be error values, if not available then error is assumed to be 0.
• Any information at the start or end of the file that is not in a 2 or 3 column format is ignored (for instance, header information may be stored here).
• Columns may be separated by commas, tabs, or spaces.
• ASCII files may contain point or histogram data, the x column in histogram data will have one more value than the y and e columns.

• The following files would all be acceptable ASCII files

  
title = plots1 xaxis = wavelength yaxis = signal 
490.2 30000
491.2 31923
492.2 40000

Represents a three point dataset with 0 error

  
title = plots1 xaxis = wavelength yaxis = signal 
490.2 30000 300
491.2 31923 300 
492.2 40000 250
493.2

Represents a 3 column histogram dataset with error data

  
490.2,30000,300
491.2,31923,300
492.2,40000,250
493.2

Will represent the same 3 column histogram dataset with error data.

• When files are written by libisis a header is written at the top of the file with the following information

    name = dataset name
    title = dataset title 
    signal_units = dataset s axis label 
    x_units = dataset x axis label
    x_distribution = 1

x1 s1 e1
x2 s2 e2 
...

where the header information is taken from the dataset being written.

To read and write data to ASCII files in