TimeMapAxis#

class gammapy.maps.TimeMapAxis(edges_min, edges_max, reference_time, name='time', interp='lin')[source]#

Bases: object

Class representing a time axis.

Provides methods for transforming to/from axis and pixel coordinates. A time axis can represent non-contiguous sequences of non-overlapping time intervals.

Time intervals must be provided in increasing order.

Parameters:

edges_minQuantity: Array of edge time values. This is the time delta w.r.t. to the reference time.
edges_maxQuantity: Array of edge time values. This is the time delta w.r.t. to the reference time.
reference_timeTime: Reference time to use.
namestr, optional: Axis name. Default is “time”.
interp{‘lin’}: Interpolation method used to transform between axis and pixel coordinates. For now only ‘lin’ is supported. Default is ‘lin’.

Attributes Summary

`as_plot_center`	Return center for plotting.
`as_plot_edges`	Return edges for plotting.
`as_plot_labels`	Return labels for plotting.
`as_plot_xerr`	Return x errors for plotting.
`bin_width`	Return time interval width as a `Quantity`.
`bounds`	Bounds of the axis as a ~astropy.units.Quantity.
`center`	Return interval centers as a `Quantity`.
`edges`	Return the array of bin edges values.
`edges_max`	Return the array of bin edges minimum values.
`edges_min`	Return the array of bin edges maximum values.
`interp`	Interpolation scale of the axis.
`is_contiguous`	Whether the axis is contiguous.
`iter_by_edges`	Iterate by intervals defined by the edges.
`name`	Return the axis name.
`nbin`	Return the number of bins in the axis.
`node_type`
`reference_time`	Return reference time used for the axis.
`time_bounds`	Bounds of the axis as a ~astropy.units.Quantity.
`time_delta`	Return axis time bin width as a `TimeDelta` object.
`time_edges`	Time edges as a `Time` object.
`time_format`
`time_max`	Return axis upper edges as a `Time` object.
`time_mid`	Return time bin center as a `Time` object.
`time_min`	Return axis lower edges as `Time` object.
`unit`	Axis unit.

Methods Summary

`assert_name`(required_name)	Assert axis name if a specific one is required.
`coord_to_idx`(coord, **kwargs)	Transform time axis coordinate to bin index.
`coord_to_pix`(coord, **kwargs)	Transform time axis coordinate to pixel position.
`copy`(**kwargs)	Copy `TimeMapAxis` instance and overwrite given attributes.
`downsample`()	Not supported for time axis.
`format_plot_xaxis`(ax)	Format the x-axis.
`from_gti`(gti[, name])	Create a time axis from an input GTI.
`from_gti_bounds`(gti, t_delta[, name])	Create a time axis from an input GTI.
`from_table`(table[, format, idx])	Create time map axis from table
`from_time_bounds`(time_min, time_max, nbin[, ...])	Create linearly spaced time axis from bounds.
`from_time_edges`(time_min, time_max[, unit, ...])	Create TimeMapAxis from the time interval edges defined as a `Time` object.
`group_table`(interval_edges)	Compute bin groups table for the TimeMapAxis, given coarser bin edges.
`is_aligned`(other[, atol])	Not supported for time axis.
`is_allclose`(other, **kwargs)	Check if other time map axis is all close.
`pix_to_coord`(pix)	Transform from pixel position to time coordinate.
`pix_to_idx`(pix[, clip])
`slice`(idx)	Create a new axis object by extracting a slice from this axis.
`squash`()	Create a new axis object by squashing the axis into one bin.
`to_contiguous`()	Make the time axis contiguous.
`to_gti`()	Convert the axis to a GTI table.
`to_header`([format, idx])	Create FITS header.
`to_table`()	Create table.
`upsample`()	Not supported for time axis.

Attributes Documentation

as_plot_center#: Return center for plotting.

as_plot_edges#: Return edges for plotting.

as_plot_labels#: Return labels for plotting.

as_plot_xerr#: Return x errors for plotting.

bin_width#: Return time interval width as a Quantity.

bounds#: Bounds of the axis as a ~astropy.units.Quantity.

center#: Return interval centers as a Quantity.

edges#: Return the array of bin edges values.

edges_max#: Return the array of bin edges minimum values.

edges_min#: Return the array of bin edges maximum values.

interp#: Interpolation scale of the axis.

is_contiguous#: Whether the axis is contiguous.

iter_by_edges#: Iterate by intervals defined by the edges.

name#: Return the axis name.

nbin#: Return the number of bins in the axis.

node_type = 'intervals'#

reference_time#: Return reference time used for the axis.

time_bounds#: Bounds of the axis as a ~astropy.units.Quantity.

time_delta#: Return axis time bin width as a TimeDelta object.

time_edges#: Time edges as a Time object.

time_format = 'iso'#

time_max#: Return axis upper edges as a Time object.

time_mid#: Return time bin center as a Time object.

time_min#: Return axis lower edges as Time object.

unit#: Axis unit.

Methods Documentation

assert_name(required_name)[source]#

Assert axis name if a specific one is required.

Parameters:

required_namestr: Required name.

coord_to_idx(coord, **kwargs)[source]#

Transform time axis coordinate to bin index.

Indices of time values falling outside time bins will be set to -1.

Parameters:

coordTime or Quantity: Array of time axis coordinate values. The quantity is assumed to be relative to the reference time.

Returns:

idxndarray: Array of bin indices.

coord_to_pix(coord, **kwargs)[source]#

Transform time axis coordinate to pixel position.

Pixels of time values falling outside time bins will be set to -1.

Parameters:

coordTime: Array of time axis coordinate values.

Returns:

pixndarray: Array of pixel positions.

copy(**kwargs)[source]#

Copy TimeMapAxis instance and overwrite given attributes.

Parameters:

**kwargsdict, optional: Keyword arguments to overwrite in the map axis constructor.

Returns:

copyTimeMapAxis: Copied time map axis.

downsample()[source]#: Not supported for time axis.

format_plot_xaxis(ax)[source]#

Format the x-axis.

Parameters:

axAxis: Plot axis to format.

Returns:

axAxis: Formatted plot axis.

classmethod from_gti(gti, name='time')[source]#

Create a time axis from an input GTI.

Parameters:

gtiGTI: GTI table.
namestr, optional: Axis name. Default is “time”.

Returns:

axisTimeMapAxis: Time map axis.

classmethod from_gti_bounds(gti, t_delta, name='time')[source]#

Create a time axis from an input GTI.

The unit for the axis is taken from the t_delta quantity.

Parameters:

gtiGTI: GTI table.
t_deltaQuantity: Time binning.
namestr, optional: Axis name. Default is “time”.

Returns:

axisTimeMapAxis: Time map axis.

classmethod from_table(table, format='gadf', idx=0)[source]#

Create time map axis from table

Parameters:

tableTable: Bin table HDU.
format{“gadf”, “fermi-fgl”, “lightcurve”}: Format to use. Default is “gadf”.
idxint: Axis index. Default is 0.

Returns:

axisTimeMapAxis: Time map axis.

classmethod from_time_bounds(time_min, time_max, nbin, unit='d', name='time')[source]#

Create linearly spaced time axis from bounds.

Parameters:

time_minTime: Lower bound.
time_maxTime: Upper bound.
nbinint: Number of bins.
unitUnit or str, optional: The unit to convert the edges to. Default is ‘d’ (day).
namestr, optional: Name of the axis. Default is “time”.

classmethod from_time_edges(time_min, time_max, unit='d', interp='lin', name='time')[source]#

Create TimeMapAxis from the time interval edges defined as a Time object.

The reference time is defined as the lower edge of the first interval.

Parameters:

time_minTime: Array of lower edge times.
time_maxTime: Array of lower edge times.
unitUnit or str, optional: The unit to convert the edges to. Default is ‘d’ (day).
interp{‘lin’}: Interpolation method used to transform between axis and pixel coordinates. Currently, only ‘lin’ is supported. Default is ‘lin’.
namestr, optional: Axis name. Default is “time”.

Returns:

axisTimeMapAxis: Time map axis.

group_table(interval_edges)[source]#

Compute bin groups table for the TimeMapAxis, given coarser bin edges.

Parameters:

interval_edgeslist of Time or Quantity: Start and stop time for each interval to compute the LC.

Returns:

groupsTable

Group table. Bin groups are divided in:

“normal” for the bins containing data
“underflow” for the bins falling below the minimum axis threshold
“overflow” for the bins falling above the maximum axis threshold
“outflow” for other states

is_aligned(other, atol=0.02)[source]#: Not supported for time axis.

is_allclose(other, **kwargs)[source]#

Check if other time map axis is all close.

Parameters:

otherTimeMapAxis: Other time map axis.
**kwargsdict, optional: Keyword arguments forwarded to allclose.

Returns:

is_allclosebool: Whether the other time map axis is allclose.

pix_to_coord(pix)[source]#

Transform from pixel position to time coordinate. Currently, works only for linear interpolation scheme.

Parameters:

pixndarray: Array of pixel positions.

Returns:

coordTime: Array of time axis coordinate values.

static pix_to_idx(pix, clip=False)[source]#

slice(idx)[source]#

Create a new axis object by extracting a slice from this axis.

Parameters:

idxslice: Slice object selecting a sub-selection of the axis.

Returns:

axisTimeMapAxis: Sliced time map axis object.

Examples

>>> from gammapy.maps import TimeMapAxis
>>> import astropy.units as u
>>> from astropy.time import Time
>>> time_map_axis = TimeMapAxis(
...     edges_min=[1, 5, 10, 15] * u.day,
...     edges_max=[2, 7, 13, 18] * u.day,
...     reference_time=Time("2020-03-19"),
... )
>>> slices = slice(1, 3)
>>> sliced = time_map_axis.slice(slices)

squash()[source]#

Create a new axis object by squashing the axis into one bin.

Returns:

axisTimeMapAxis: Squashed time map axis object.

to_contiguous()[source]#

Make the time axis contiguous.

Returns:

axisTimeMapAxis: Contiguous time axis.

to_gti()[source]#

Convert the axis to a GTI table.

Returns:

gtiGTI: GTI table.

to_header(format='gadf', idx=0)[source]#

Create FITS header.

Parameters:

format{“ogip”}: Format specification. Default is “gadf”.
idxint, optional: Column index of the axis. Default is 0.

Returns:

headerHeader: Corresponding FITS header.

to_table()[source]#

Create table.

Returns:

tableTable: Table with axis data.

upsample()[source]#: Not supported for time axis.