How to Parse the SRTN Output File (to a gnuplot usable format) - BenningtonCS/Telescope-2014 GitHub Wiki

Before you may start to plot your fresh data, it has to parsed out into a format that is readable by the gnuplot plotting program. Some scripts for parsing output data into certain formats already exist; they are found in the utils/gnuplot directory. They are described in more detail below.

The meta_parse script lists columns of data in the order: Date, obsn, az, el, center freq, Tsys, Tant, vlsr, galactic latitude, galactic longitude, source, fstart, fstop, spacing, bw, fbw, nfreq, nsam, npoint, integ, sigma, bsw.

The spectrum_parse script lists each frequency in the spectrum in the first column, and then the power values associated with each frequency in each subsequent columns.

There is also a spectrum parsing program specific for parsing out rotation curve survey files. This file is called rot_curve_spec_parse.py, and the usage is the same as the previous two programs. The printing of the data is a little different, however. The first column prints the frequency channels present in the spectrum like the other parser, but then prints the velocities associated with the red/blueshift of the frequencies away from the 1420.406 MHz cetner frequency in the second column. The next column is the average spectrum for glon 0, then glon 10, then glon 20, and so on until glon 90.

Below is a more detailed look at the usage of each of these scripts, taken from the README in the utils/gnuplot directory.

---

utilities for srtn+gnuplot

note: these scripts are Python 2.7 compatible, though not yet Python 3.x compatible.

This folder contains a collection of scripts which are used to manipulate srtn output data to format it in a particular way that is compatible with the gnuplot tool. Below is a summary of the usage information for each of the scripts. The same information can be found by running each script with the -h or --help flag

In the examples subdirectory exist example output files generated from these scripts.

Overview

The scripts in this directory are all run basically the same way. They take a file name as input, and have an optional input argument for the output file name. If no output file name is specified, a default one will be chosen, which will take the form:

  <PARSER_IDENTIFIER>_YYYY_MM_DD.hh-mm-ss.txt

To specify the output file name, use the -o or --output flag when running the script. The help information for each script can be viewed by using the -h or --help flag.

The files generated from running the parse scripts are formatted such that they work with gnuplot. Once all desired files are converted from srtn-format to the gnuplot-compatible format, they should be ready for use with gnuplot (see wiki entry on how to use gnuplot)

Examples

Running a script with no optional arguments

$ python meta_parse.py test_data.rad

Running a script, specifying the output filename

$ python meta_parse.py test_data.rad -o meta_output.txt

View the help information for a parse script

$ python spectrum_parse.py -h

Scripts

meta_parse.py

usage: meta_parse.py [-h] [-o OUTPUT] input_file

parser to format data into a gnuplot-readable form. meta_parse extracts the
meta-information recorded for each observation in the data file. the output
fileit generates contains rows for every observation with associated meta-
information and columns corresponding to each bit of meta-information, e.g.:

date, obsn, az, el, freq_MHz, Tsys, Tant, vlsr, glat, glon, source, Fstart,
fstop, spacing, bw, fbw, nfreq, nsam, npoint, integ, sigma

positional arguments:
  input_file            name of the file to parse

optional arguments:
  -h, --help            show this help message and exit
  -o OUTPUT, --output OUTPUT
                        name of the output file. if unspecified, the file will
                        be named in the format: YYYY_MM_DD.hh-mm-ss.txt

rot_curve_spec_parse.py

usage: rot_curve_spec_parse.py [-h] [-o OUTPUT] input_file

parser to format srtn spectrum data into a gnuplot-readable form. this parses
a file for rotation curve surveys. it averages all spectra taken at a single
point in the galactic plane to produce an average spectrum for that point. the
velocities associated with frequencies red/blueshifted from the center freq.
of 1420.406 MHz are also calculated.


positional arguments:
  input_file            name of the file to parse

optional arguments:
  -h, --help            show this help message and exit
  -o OUTPUT, --output OUTPUT
                        name of the output file. if unspecified, the file will
                        be named in the format: YYYY_MM_DD.hh-mm-ss.txt

hi_spec_parse.py

usage: HI_spec_parse.py [-h] [-o OUTPUT] input_file

parser to format srtn spectrum data into a gnuplot-readable form. this parses
a file for rotation curve surveys. it prints the column numbers of the last
spectrum taken before the telescope moved to the next point. the velocities
associated with frequencies red/blueshifted from the center freq. of 1420.406
MHz are also calculated.

positional arguments:
  input_file            name of the file to parse

optional arguments:
  -h, --help            show this help message and exit
  -o OUTPUT, --output OUTPUT
                        name of the output file. if unspecified, the file will
                        be named in the format: YYYY_MM_DD.hh-mm-ss.txt

spectrum_parse.py

usage: spectrum_parse.py [-h] [-o OUTPUT] input_file

parser to format data into a gnuplot-readable form. spectrum_parse extracts
the recorded spectrum power for each observed frequency. the output file it
generates contains rows for every frequency observed with columns containing
the observed power for each observation.

positional arguments:
  input_file            name of the file to parse

optional arguments:
  -h, --help            show this help message and exit
  -o OUTPUT, --output OUTPUT
                        name of the output file. if unspecified, the file will
                        be named in the format: YYYY_MM_DD.hh-mm-ss.txt