adc (inplace=True, expanded=False): correctly handle NaNs.

When converting physical to digital sample arrays, we must replace NaN
values (which represent a missing sample) with the appropriate
invalid-sample sentinel value.

This is done correctly for normal uses of the package, but if the
application directly invoked adc(inplace=True), NaNs would not have
been handled (and were instead set to an implementation-defined
value.)

(Note that we don't use inplace=True internally because this
overwrites the original floating-point array.  Applications may want
to use inplace=True to save memory, but this requires knowing that the
original array is no longer needed.)

Author: Benjamin Moody

wfdb/io/_signal.py

@@ -562,6 +562,12 @@ def adc(self, expanded=False, inplace=False):
                 np.add(p_signal, self.baseline, p_signal)
                 np.round(p_signal, 0, p_signal)
                 d_signal = p_signal.astype(intdtype, copy=False)
+
+                if nanlocs.any():
+                    for ch in range(d_signal.shape[1]):
+                        if nanlocs[:, ch].any():
+                            d_signal[nanlocs[:, ch], ch] = d_nans[ch]
+
                 self.d_signal = d_signal
                 self.p_signal = None