Histogram: use silx by default

nabu/misc/histogram.py

 from math import log2, ceil
 import numpy as np
+from silx.math import Histogramnd
 from tomoscan.io import HDF5File
 from ..utils import check_supported
 from ..resources.logger import LoggerOrPrint
@@ -13,17 +14,11 @@ class PartialHistogram:
     data are readily available in-memory.
     """
 
-    histogram_methods = [
-        "fixed_bins_width",
-        "fixed_bins_number"
-    ]
+    histogram_methods = ["fixed_bins_width", "fixed_bins_number"]
+    bin_width_policies = ["uint16"]
+    backends = ["numpy", "silx"]
 
-    bin_width_policies = [
-        "uint16",
-    ]
-
-
-    def __init__(self, method="fixed_bins_width", bin_width="uint16", num_bins=None, min_bins=None):
+    def __init__(self, method="fixed_bins_width", bin_width="uint16", num_bins=None, min_bins=None, backend="silx"):
         """
         Initialize a PartialHistogram class.
 
@@ -49,9 +44,14 @@ class PartialHistogram:
             Number of bins when method = 'fixed_bins_number'.
         min_bins: int, optional
             Minimum number of bins when method = 'fixed_bins_width'.
+        backend: str, optional
+            Which histogram backend to use for computations. Available are "silx", "numpy".
+            Fastest is "silx".
         """
         check_supported(method, self.histogram_methods, "histogram computing method")
         self.method = method
+        check_supported(backend, self.backends, "histogram backend")
+        self.backend = backend
         self._set_bin_width(bin_width)
         self._set_num_bins(num_bins)
         self.min_bins = min_bins
@@ -114,7 +114,13 @@ class PartialHistogram:
         if data.ndim > 1:
             data = data.ravel()
         dmin, dmax = data.min(), data.max() if data_range is None else data_range
-        res = np.histogram(data, bins=self.num_bins)
+        if self.backend == "numpy":
+            res = np.histogram(data, bins=self.num_bins)
+        elif self.backend == "silx":
+            histogrammer = Histogramnd(
+                data, n_bins=self.num_bins, histo_range=(dmin, dmax), last_bin_closed=True
+            )
+            res = histogrammer.histo, histogrammer.edges[0]
         return res
 
 
@@ -232,8 +238,8 @@ class VolumeHistogram:
             except KeyError:
                 msg = str(
                     "Could not access HDF5 path %s in file %s. Please check that this file \
-                    actually contains a reconstruction and that the HDF5 entry %s is correct"
-                    % (self.data_path, self.fname, self.entry)
+                    actually contains a reconstruction and that the HDF5 path is correct"
+                    % (self.data_path, self.fname)
                 )
                 self.logger.fatal(msg)
                 raise ValueError(msg)