Axis

class histpy.Axis(edges, label=None, scale=None, unit=None, copy=True)

Bases: object

Bin edges. Optionally labeled

You can select specific edges using the slice operator ([]). The result is also another Axis object.

Parameters:

• edges (array-like) – Bin edges. Can be a Quantity array, if you need units

• label (str) – Label for axis. If edges is an Axis object, this will override its label

• scale (str) – Bin center mode e.g. “linear” or “log”. See axis_scale property. If edges is an Axis object, this will override its mode

• unit (unit-like) – Unit for axis (will override unit of edges)

• copy (bool) – True if edge array should be distinct from passed-in edges; if False, will use same edge array if possible

copy()

Make a deep copy of self

replace_edges(edges, copy=True)

Replace edge array of self (see _copy documentation)

property unit

Return the astropy units of the axis. Or None is units where not declare.

to(unit, equivalencies=[], update=True, copy=True)

Convert an Axis to a different unit.

Parameters:

• unit (unit-like) – Unit to convert to.

• equivalencies (list or tuple) – A list of equivalence pairs to try if the units are not directly convertible.

• update (bool) – If update is False, only the units will be changed without updating the edges accordingly

• copy (bool) – If True (default), then the value is copied. Otherwise, a copy will only be made if necessary.

property axis_scale

Control what is considered the center of the bin. This affects centers() and interpolation.

Modes:

• linear (default): The center is the midpoint between the bin edges

• symmetric: same as linear, except for the first center, which will correspond to the lower edge. This is, for example, useful when the histogram is filled with the absolute value of a variable.

• log: The center is the logarithmic (or geometrical) midpoint between the bin edges.

find_bin(value, right=False)

Return the bin value corresponds to.

Parameters:

• value – scalar or np.ndarray value(s) to bin

• right – bool If false, a bin strictly includes its left edge If true, a bin strictly includes its right edge

Returns:

Bin number. -1 for underflow, nbins for overflow

Return type:

int

interp_weights(values)

Get the two closest bins to each value in values, together with the weights to linearly interpolate between the centers of these two bins.

If the axis has log scale, interpolation weights are computed in the log domain, and values must be > 0.

Before interpolation, values are be clamped to be at least the center of the first bin and at most the center of the last bin.

Returns:

int array containing left and right bins for each value, of shape

(2,) if values is scalar or 0-D array, (2, values.shape) otherwise

Weights: float array containing left and right weights for each value, of shape

(2,) if values is scalar or 0-D array, (2, values.shape) otherwise

Return type:

Bins

NB: return values are for compatibility with old code; it would suffice to return bins[0] and weights[0], since bins[1] = bins[0] + 1 and weights[1] = 1. - weights[0].

property lower_bounds

Lower bound of each bin

property upper_bounds

Upper bound of each bin

property bounds

Start of [lower_bound, upper_bound] values for each bin.

property lo_lim

Overall lower bound

property hi_lim

Overall upper bound of histogram

property edges

Edges of each bin

property label

Axis label

property label_with_unit

Axis ‘label [units]’

property centers

Center of each bin, in linear domain and axis units, if any

property widths

Width of each bin.

property nbins

Number of elements along each axis. Either an int (1D histogram) or an array