Causes the specified information to be written to the screen or to a file.
sherpa> WRITE <arg> [# [ID]] [<filename> [<filetype>]]
# specifies the number of the dataset (default dataset number is 1).
The ID modifier is used for writing background datasets, and then if
and only if the Sherpa state object variable multiback is set to 1,
i.e., if more than one background dataset is to be associated with a
single source dataset. The ID modifier may be any unreserved string
(e.g., A, foo, etc.), i.e., a string that is not a parsable command.
The name of the file to which data is written is <filename>. If
<filename> is not specified, information is written to the screen.
The argument <arg_n> may be any of the following:
WRITE Command Arguments
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{DATA | DCOUNTS}
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The source data values
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{BACK | BDCOUNTS}
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The background data values
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ERRORS
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The errors associated with source data points
|
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BERRORS
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The errors associated with background data points
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{SYSERRORS |
BSYSERRORS}
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The assigned systematic errors for the source|background data values
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{STATERRORS |
BSTATERRORS}
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The estimated statistical errors for the source|background data values
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{{MODEL | MCOUNTS} |
{BMODEL | BMCOUNTS}}
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The (convolved) source|background model amplitudes
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{DELCHI |
BDELCHI}
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The sigma residuals of the source|background fit: (data - model)/error
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{RESIDUALS |
BRESIDUALS}
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The absolute residuals of the source|background fit: (data - model)
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{RATIO |
BRATIO}
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The ratio (data/model) for source|background
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{CHI SQU |
BCHISQU}
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The contributions to the chi-square statistic
from each source|background data point
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{STATISTIC |
BSTATISTIC}
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The contributions to the current statistic
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{WEIGHT |
BWEIGHT}
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The statistic weight value assigned to each source|background data point
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{FILTER |
BFILTER}
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The mask value (0|1) for each source|background data point
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{GROUP |
BGROUP}
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The grouping value (1|-1) associated with
each source|background data point
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{QUALITY |
BQUALITY}
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The quality value (0|2|5) associated with
each source|background data point
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<sherpa_model_stack>
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The (unconvolved) model amplitudes for the
specified model stack (SOURCE,
{BACKGROUND|BG},
[B]NOISE, or
KERNEL)
|
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<model_stack>
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The (unconvolved) model amplitudes for the
specified user-defined model stack
|
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<sherpa_modelname>
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The (unconvolved) amplitudes of the specified model component
(e.g., GAUSS)
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<modelname>
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The (unconvolved) amplitudes of the specified model component
(e.g., g)
|
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{ARF |
BARF}
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The unfiltered source|background ARF file contents
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{EXPMAP |
BEXPMAP}
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The unfiltered source|background exposure map file contents
|
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{PSF |
BPSF}
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The unfiltered source|background PSF file contents
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| MDL |
A model descriptor list file. |
The argument <filetype> can specify the
desired format for the file that is written:
WRITE File Type Arguments
| ASCII | 1-D ASCII |
| FITS | 2-D FITS image |
| FITSIMAGE | 2-D FITS image |
| FITSBIN | 1-D FITS binary table |
| PHA | PHA file |
Note the following:
-
if <filetype> is not specified,
the default output file format is ASCII for 1-D data and
FITS for 2-D data.
-
the WRITE command utilizes the settings of
ANALYSIS and
PLOTY
to determine the units of the output. An exception to this
rule in CIAO 3.0 is the writing out of data to PHA format files; here,
counts are written out regardless of the setting of PLOTY.
-
if the data are grouped, then the channels in the file produced by
WRITE DATA ... PHA will represent the grouped
channels. However, since no grouping information is written to the
file, the bin energies will be incorrect. Therefore,
WRITE ... PHA should be used only with ungrouped
data.
-
the VARMM/S-Lang module functions writeascii
and writefits,
which may be used within Sherpa, provide alternate
means of writing data to disk.
The WRITE command may be issued at any time. Each time
the command is issued the specified file
<filename> is overwritten, but only if the
state variable sherpa.clobber is set to 1. Otherwise, an
error message is displayed if the file exists.
This command is able to take any Data Model virtual file
specification (see "ahelp dmsyntax"). If you can do
unix% dmcopy "infile.fits[spec 1][spec 2]" outfile.fits
you can also do
sherpa> write "infile.fits[spec 1][spec 2]"
This is especially useful when working with very large files. For
example:
sherpa> write "evt.fits[bin sky=4][opt mem=100]"
bins the event file by a factor of four and allocates additional
memory.
Write an ASCII dataset to a backup ASCII file:
sherpa> READ DATA 2 example.dat 1 2
sherpa> WRITE DATA 2 example_backup.dat
Write X-Axis: Bin Y-Axis: Flux (Counts)
sherpa> WRITE DATA 2 example_backup.dat
Write X-Axis: Bin Y-Axis: Flux (Counts)
Error: file exists and sherpa.clobber = 0.
sherpa> sherpa.clobber = 1
sherpa> WRITE DATA 2 example_backup.dat
Write X-Axis: Bin Y-Axis: Flux (Counts)
The second command writes dataset number 2 to
an ASCII file named example_backup.dat. This
file cannot be overwritten unless the state variable
sherpa.clobber is set to 1.
Write a PHA dataset to a backup ASCII file:
sherpa> READ DATA example.pha
The inferred file type is PHA. If this is not what you want, please
specify the type explicitly in the data command.
WARNING: using systematic errors specified in the PHA file.
RMF is being input from:
<directory_path>/example.rmf
ARF is being input from:
<directory_path>/example.arf
Background data are being input from:
<directory_path>/example_bkg.pha
sherpa> WRITE DATA pha.dat ASCII
Write X-Axis: Energy (keV) Y-Axis: Flux (Counts/sec/keV)
Note that the ASCII argument in the command
WRITE DATA pha.dat ASCII
is not actually needed, since the default for 1-D data is ASCII format.
Extract three columns from a FITSBIN file and write them to an ASCII file:
sherpa> READ DATA "example1_bin.fits[cols x1,x2,x3]" FITSBIN
sherpa> WRITE DATA threecols.txt ASCII 1 2 3
Write X-Axes: (Bin,Bin) Y-Axis: Counts
Make a fit to data and save the best-fit
amplitudes for one of the model components, along
with information about the fit:
sherpa> ERASE ALL
sherpa> READ DATA example1.dat
sherpa> PARAMPROMPT OFF
Model parameter prompting is off
sherpa> SOURCE = POLY[p1] + POW[p2]
sherpa> FIT
LVMQT: V2.0
LVMQT: initial statistic value = 3070.54
LVMQT: final statistic value = 0.252662 at iteration 14
p1.c0 0.256496
p2.gamma -2.03063
p2.ampl 15.6881
sherpa> WRITE p2 powlaw.mod ASCII
Write X-Axis: Bin Y-Axis: Flux (Photons/bin)
sherpa> WRITE SOURCE source.mod
Write X-Axis: Bin Y-Axis: Flux (Photons/bin)
sherpa> var1 = get_axes(1)
sherpa> print(var1)
axistype = Channels
axisunits = unknown
lo = NULL
hi = NULL
mid = Float_Type[8]
sherpa> var2 = get_data(1)
sherpa> var3 = get_errors(1)
sherpa> var4 = get_mcounts(1)
sherpa> writeascii("fit.dat",var1.mid,var2,var3,var4)
The last command writes out a 4-column file with x-axis values and
associated data, errors, and predicted model counts.
- chandra
-
guide
- sherpa
-
get_analysis,
get_arf_axes,
get_axes,
get_coord,
get_data,
get_energy_axes,
get_errors,
get_filter,
get_filter_expr,
get_fit,
get_fluxed_spectrum,
get_ftest,
get_metadata,
get_photon_axes,
get_photon_energy_axes,
get_photon_wave_axes,
get_qvalue,
get_raw_axes,
get_record,
get_source,
get_statistic,
get_stats,
get_syserrors,
get_wave_axes,
get_weights,
record,
save
|
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