new features for signal processing class

docs/api_py/operations/operation_documentation.rst

@@ -27,3 +27,8 @@ Documentation
 
 .. autoclass:: Shear
 .. autoclass:: Scale
+
+.. currentmodule:: mrsimulator.signal_processor.correction
+
+.. autoclass:: Phase
+.. autoclass:: AutoPhaseCorrect

src/mrsimulator/signal_processor/__init__.py

@@ -8,6 +8,7 @@
 from . import affine as af  # noqa:F401
 from . import apodization as ap  # noqa:F401
 from . import baseline as bl  # noqa:F401
+from . import correction as cf  # noqa:F401
 from ._base import Operation
 
 

src/mrsimulator/signal_processor/correction.py

@@ -0,0 +1,93 @@
+"""The Event class."""
+from typing import ClassVar
+from typing import Dict
+from typing import Union
+
+import numpy as np
+from pydantic import validator
+
+from .apodization import Apodization
+from .utils import _str_to_quantity
+from .utils import CONST
+
+__author__ = "Deepansh Srivastava"
+
+
+class Correction(Apodization):
+    module_name: ClassVar[str] = __name__
+
+    @property
+    def function(self):
+        return "correction"
+
+
+class Phase(Correction):
+    r"""Phase modulate the dependent variables of CSDM dataset following
+
+    .. math::
+        f(x) = e^{-i \phi_0} * e^{-i 2 \pi \phi_1 * x},
+
+    where :math:`x` are the dimension coordinates, and :math:`\phi_0`,
+    :math:`\phi_1` are the constant and linear phase, respectively.
+
+    Arguments
+    ---------
+
+    constant:
+        The constant phase, :math:`\phi_0` in radians. Default is 0.
+
+    linear:
+        The linear phase, :math:`\phi_1`. Default is 0.
+
+    dim_index:
+        CSDM dimension index along which the operation applies. The
+        default is the dimension at index 0.
+
+    dv_index:
+        CSDM dependent variable index where the operation applies. If
+        unspecified, the operation applies to all dependent variables.
+
+    Example
+    -------
+
+    >>> operation4 = sp.correction.Phase(constant=2.14, linear="25.5 Hz", dim_index=0)
+    """
+
+    constant: Union[float, str] = 0
+    linear: Union[float, str] = 0
+    property_units: Dict = {"constant": CONST, "linear": CONST}
+
+    @validator("constant")
+    def str_to_quantity_constant(cls, v, values):
+        return _str_to_quantity(v, values, "constant")
+
+    @validator("linear")
+    def str_to_quantity_linear(cls, v, values):
+        return _str_to_quantity(v, values, "linear")
+
+    def fn(self, x):
+        x = self.get_coordinates_in_units(x, unit=1.0 / self.property_units["linear"])
+        vec = np.exp(-1j * self.constant) * np.exp(-1j * 2 * np.pi * self.linear * x)
+        return vec
+
+
+class AutoPhaseCorrect(Apodization):
+    def operate(self, dataset):
+        """Apply the operation function.
+
+        Args:
+            dataset: A CSDM object.
+        """
+        max_index = np.unravel_index(int(np.argmax(dataset)), dataset.shape[::-1])
+        max_index = max_index[::-1]
+
+        for dim_idx, dim in enumerate(dataset.x):
+            dim.coordinates_offset = -dim.coordinates[max_index[dim_idx]]
+
+        dv_indexes = self._get_dv_indexes(self.dv_index, n=len(dataset.y))
+        for index in dv_indexes:
+            phase_0 = np.angle(dataset[max_index].y[index].components[0])
+            multiplier = np.exp(-1j * phase_0)
+            dataset.y[index].components *= multiplier
+
+        return dataset