added fake _xdr attributes in case the trajectory was constructed by other means than reading a gromacs xtc file

src/mdevaluate/autosave.py

@@ -166,8 +166,10 @@ def autosave_data(
         @functools.wraps(function)
         def autosave(*args, **kwargs):
             description = kwargs.pop("description", "")
+            autosave_dir_overwrite = kwargs.pop("autosave_dir_overwrite", None)
+            autosave_dir = autosave_dir_overwrite if autosave_dir_overwrite is not None else autosave_directory
             autoload = kwargs.pop("autoload", True) and load_autosave_data
-            if autosave_directory is not None:
+            if autosave_dir is not None:
                 relevant_args = list(args[:nargs])
                 if kwargs_keys is not None:
                     for key in [*posargs_keys, *kwargs_keys]:

src/mdevaluate/checksum.py

@@ -102,8 +102,20 @@ def checksum(*args, csum=None, _seen=None):
         _seen.add(obj_id)
 
         if hasattr(arg, "__checksum__"):
-            logger.debug("Checksum via __checksum__: %s", str(arg))
-            csum.update(str(arg.__checksum__()).encode())
+            method = getattr(arg, "__checksum__")
+            if callable(method) and not isinstance(arg, type):
+                logger.debug("Checksum via __checksum__: %s", str(arg))
+                csum.update(str(method()).encode())
+            elif isinstance(arg, type):
+                try:
+                    src = inspect.getsource(arg)
+                    csum.update(strip_comments(src).encode())
+                    logger.debug("Checksum via class source for %s", arg.__name__)
+                except (OSError, TypeError):
+                    csum.update(arg.__name__.encode())
+                    logger.debug("Checksum via class name for %s", arg.__name__)
+            else:
+                logger.debug("Skipping unbound __checksum__ on %s", type(arg))
         elif isinstance(arg, bytes):
             csum.update(arg)
         elif isinstance(arg, str):

src/mdevaluate/coordinates.py

@@ -434,6 +434,34 @@ def center_of_masses(
         ]
     ).T[mask]
     return np.array(positions)
+    
+    
+@map_coordinates
+def center_of_atoms(
+    frame: CoordinateFrame, atom_indices=None, shear: bool = False
+) -> NDArray:
+    if atom_indices is None:
+        atom_indices = list(range(len(frame)))
+    res_ids = frame.residue_ids[atom_indices]
+    if shear:
+        coords = frame[atom_indices]
+        box = frame.box
+        sort_ind = res_ids.argsort(kind="stable")
+        i = np.concatenate([[0], np.where(np.diff(res_ids[sort_ind]) > 0)[0] + 1])
+        coms = coords[sort_ind[i]][res_ids - min(res_ids)]
+        cor = pbc_diff(coords, coms, box)
+        coords = coms + cor
+    else:
+        coords = frame.whole[atom_indices]
+    mask = np.bincount(res_ids)[1:] != 0
+    positions = np.array(
+        [
+            np.bincount(res_ids, weights=c)[1:]
+            / np.bincount(res_ids)[1:]
+            for c in coords.T
+        ]
+    ).T[mask]
+    return np.array(positions)
 
 
 @map_coordinates

src/mdevaluate/correlation.py

@@ -18,7 +18,7 @@ def log_indices(first: int, last: int, num: int = 100) -> np.ndarray:
     return np.unique(np.int_(ls) - 1 + first)
 
 
-@autosave_data(2)
+@autosave_data(nargs=2, kwargs_keys=('selector', 'segments', 'skip', 'window', 'average', 'points',), version=1.0)
 def shifted_correlation(
     function: Callable,
     frames: Coordinates,
@@ -147,7 +147,8 @@ def shifted_correlation(
     num_frames = int(len(frames) * window)
     ls = np.logspace(0, np.log10(num_frames + 1), num=points)
     idx = np.unique(np.int_(ls) - 1)
-    t = np.array([frames[i].time for i in idx]) - frames[0].time
+    dt = round(frames[1].time - frames[0].time, 6) # round to avoid bad floats
+    t = idx * dt
 
     result = np.array(
         [
@@ -199,7 +200,7 @@ def msd(
         raise ValueError('Parameter axis has to be ether "all", "x", "y", or "z"!')
 
 
-def isf(
+def isf_raw(
     start_frame: CoordinateFrame,
     end_frame: CoordinateFrame,
     q: float = 22.7,
@@ -216,29 +217,59 @@ def isf(
         displacements = displacements_without_drift(start_frame, end_frame, trajectory)
     if axis == "all":
         distance = (displacements**2).sum(axis=1) ** 0.5
-        return np.sinc(distance * q / np.pi).mean()
+        return np.sinc(distance * q / np.pi)
     elif axis == "xy" or axis == "yx":
         distance = (displacements[:, [0, 1]]**2).sum(axis=1) ** 0.5
-        return np.real(jn(0, distance * q)).mean()
+        return np.real(jn(0, distance * q))
     elif axis == "xz" or axis == "zx":
         distance = (displacements[:, [0, 2]]**2).sum(axis=1) ** 0.5
-        return np.real(jn(0, distance * q)).mean()
+        return np.real(jn(0, distance * q))
     elif axis == "yz" or axis == "zy":
         distance = (displacements[:, [1, 2]]**2).sum(axis=1) ** 0.5
-        return np.real(jn(0, distance * q)).mean()
+        return np.real(jn(0, distance * q))
     elif axis == "x":
         distance = np.abs(displacements[:, 0])
-        return np.mean(np.cos(np.abs(q * distance)))
+        return np.cos(np.abs(q * distance))
     elif axis == "y":
         distance = np.abs(displacements[:, 1])
-        return np.mean(np.cos(np.abs(q * distance)))
+        return np.cos(np.abs(q * distance))
     elif axis == "z":
         distance = np.abs(displacements[:, 2])
-        return np.mean(np.cos(np.abs(q * distance)))
+        return np.cos(np.abs(q * distance))
     else:
         raise ValueError('Parameter axis has to be ether "all", "x", "y", or "z"!')
 
 
+def isf(
+    start_frame: CoordinateFrame,
+    end_frame: CoordinateFrame,
+    q: float = 22.7,
+    trajectory: Coordinates = None,
+    axis: str = "all",
+) -> float:
+    """
+    Incoherent intermediate scattering function averaged over all particles.
+    See isf_raw for details.
+    """
+    return isf_raw(start_frame, end_frame, q=q, trajectory=trajectory, axis=axis).mean()
+
+
+def isf_mean_var(
+    start_frame: CoordinateFrame,
+    end_frame: CoordinateFrame,
+    q: float = 22.7,
+    trajectory: Coordinates = None,
+    axis: str = "all",
+) -> float:
+    """
+    Incoherent intermediate scattering function averaged over all particles and the
+    variance.
+    See isf_raw for details.
+    """
+    values = isf_raw(start_frame, end_frame, q=q, trajectory=trajectory, axis=axis)
+    return values.mean(), values.var()
+
+
 def rotational_autocorrelation(
     start_frame: CoordinateFrame, end_frame: CoordinateFrame, order: int = 2
 ) -> float:
@@ -430,6 +461,7 @@ def non_gaussian_parameter(
     end_frame: CoordinateFrame,
     trajectory: Coordinates = None,
     axis: str = "all",
+    full_output = False,
 ) -> float:
     r"""
     Calculate the non-Gaussian parameter.
@@ -442,27 +474,41 @@ def non_gaussian_parameter(
     else:
         vectors = displacements_without_drift(start_frame, end_frame, trajectory)
     if axis == "all":
-        r = (vectors**2).sum(axis=1)
+        r2 = (vectors**2).sum(axis=1)
         dimensions = 3
     elif axis == "xy" or axis == "yx":
-        r = (vectors[:, [0, 1]]**2).sum(axis=1)
+        r2 = (vectors[:, [0, 1]]**2).sum(axis=1)
         dimensions = 2
     elif axis == "xz" or axis == "zx":
-        r = (vectors[:, [0, 2]]**2).sum(axis=1)
+        r2 = (vectors[:, [0, 2]]**2).sum(axis=1)
         dimensions = 2
     elif axis == "yz" or axis == "zy":
-        r = (vectors[:, [1, 2]]**2).sum(axis=1)
+        r2 = (vectors[:, [1, 2]]**2).sum(axis=1)
         dimensions = 2
     elif axis == "x":
-        r = vectors[:, 0] ** 2
+        r2 = vectors[:, 0] ** 2
         dimensions = 1
     elif axis == "y":
-        r = vectors[:, 1] ** 2
+        r2 = vectors[:, 1] ** 2
         dimensions = 1
     elif axis == "z":
-        r = vectors[:, 2] ** 2
+        r2 = vectors[:, 2] ** 2
         dimensions = 1
     else:
         raise ValueError('Parameter axis has to be ether "all", "x", "y", or "z"!')
+    
+    m2 = np.mean(r2)
+    m4 = np.mean(r2**2)
+    if m2 == 0.0:
+        if full_output:
+            return 0.0, 0.0, 0.0
+        else:
+            return 0.0
+
+    alpha_2 = (m4 / ((1 + 2 / dimensions) * m2**2)) - 1
+    if full_output:
+        return alpha_2, m2, m4
+    else:
+        return alpha_2
+
 
-    return (np.mean(r**2) / ((1 + 2 / dimensions) * (np.mean(r) ** 2))) - 1

src/mdevaluate/pbc.py

@@ -149,32 +149,21 @@ def nojump(frame: CoordinateFrame, usecache: bool = True) -> CoordinateFrame:
             i0 = 0
             delta = 0
 
-        delta = (
-            delta
-            + np.array(
-                np.vstack(
-                    [m[i0 : abstep + 1].sum(axis=0) for m in reader.nojump_matrices]
-                ).T
-            )
-            @ frame.box
-        )
+        delta = (delta
+            + np.vstack(
+                [m[i0 : abstep + 1].sum(axis=0) for m in reader.nojump_matrices]
+            ).T)
 
         reader._nojump_cache[abstep] = delta
         while len(reader._nojump_cache) > NOJUMP_CACHESIZE:
             reader._nojump_cache.popitem(last=False)
-        delta = delta[selection, :]
     else:
-        delta = (
-            np.array(
-                np.vstack(
-                    [
-                        m[: frame.step + 1, selection].sum(axis=0)
-                        for m in reader.nojump_matrices
-                    ]
+        delta = np.vstack(
+                [m[: frame.step + 1, selection].sum(axis=0) for m in reader.nojump_matrices]
                 ).T
-            )
-            @ frame.box
-        )
+    
+    delta = delta[selection, :]
+    delta = np.array(delta @ frame.box)
     return frame - delta
 
 

src/mdevaluate/reader.py

@@ -23,6 +23,8 @@ from .logging_util import logger
 from . import atoms
 from .coordinates import Coordinates
 
+from unittest.mock import MagicMock
+
 CSR_ATTRS = ("data", "indices", "indptr")
 NOJUMP_MAGIC = 2016
 Group_RE = re.compile(r"\[ ([-+\w]+) \]")
@@ -240,7 +242,18 @@ def generate_nojump_matrices(trajectory: Coordinates):
     save_nojump_matrices(trajectory.frames)
 
 
+def _ensure_xdr(reader: BaseReader):
+    """Patch missing _xdr attribute for non-XDR readers (e.g. LAMMPS DumpReader)
+    with a stable mock so checksums are consistent across runs."""
+    if not hasattr(reader.rd, '_xdr'):
+        mock_xdr = MagicMock()
+        mock_xdr.offsets = np.arange(len(reader))
+        print(f"Adding mock _xdr attribute for to reader of length {len(reader)}.")
+        reader.rd._xdr = mock_xdr
+
+
 def save_nojump_matrices(reader: BaseReader, matrices: npt.ArrayLike = None):
+    _ensure_xdr(reader)
     if matrices is None:
         matrices = reader.nojump_matrices
     data = {"checksum": checksum(NOJUMP_MAGIC, checksum(reader))}
@@ -253,6 +266,7 @@ def save_nojump_matrices(reader: BaseReader, matrices: npt.ArrayLike = None):
 
 
 def load_nojump_matrices(reader: BaseReader):
+    _ensure_xdr(reader)
     zipname = nojump_load_filename(reader)
     try:
         data = np.load(zipname, allow_pickle=True)

src/mdevaluate/utils.py

@@ -334,6 +334,11 @@ def quick1etau(t: ArrayLike, C: ArrayLike, n: int = 7) -> float:
     C is C(t) the correlation function
     n is the minimum number of points around 1/e required
     """
+    # norm, if t=0 provided
+    if t[0] == 0:
+        C /= C[0]
+    C, t = C[t>0], t[t>0] # make sure t=0 is dropped
+
     # first rough estimate, the closest time. This is returned if the interpolation fails!
     tau_est = t[np.argmin(np.fabs(C - np.exp(-1)))]
     # reduce the data to points around 1/e
@@ -357,6 +362,37 @@ def quick1etau(t: ArrayLike, C: ArrayLike, n: int = 7) -> float:
     return tau_est
 
 
+def quicknongaussfit(t, C, width=2):
+    """
+    Estimates the time and height of the peak in the non-Gaussian function.
+    C is C(t) the correlation function
+    """
+    def ffunc(t,y0,A_main,log_tau_main,sig_main):
+        main_peak = A_main*np.exp(-(t - log_tau_main)**2 / (2 * sig_main**2))
+        return y0 + main_peak
+    
+    # first rough estimate, the closest time. This is returned if the interpolation fails!
+    tau_est = t[np.argmax(C)]
+    nG_max = np.amax(C)
+    try:
+        with np.errstate(invalid='ignore'):
+            corr = C[t > 0]
+            time = np.log10(t[t > 0])
+            tau = time[np.argmax(corr)]
+            mask = (time>tau-width/2) & (time<tau+width/2)
+            time = time[mask] ; corr = corr[mask]
+            nG_min = C[t > 0].min()
+            guess = [nG_min, nG_max-nG_min, tau, 0.6]
+            popt = curve_fit(ffunc, time, corr, p0=guess, maxfev=10000)[0]
+            tau_est = 10**popt[-2]
+            nG_max = popt[0] + popt[1]
+    except:
+        pass
+    if np.isnan(tau_est):
+        tau_est = np.inf
+    return tau_est, nG_max
+
+
 def susceptibility(
     time: NDArray, correlation: NDArray, **kwargs
 ) -> tuple[NDArray, NDArray]: