--- a
+++ b/src/LFBNet/data_loader.py
@@ -0,0 +1,230 @@
+"""
+
+"""
+import os
+import glob
+import numpy as np
+from numpy import ndarray
+import matplotlib.pyplot as plt
+import nibabel as nib
+from typing import List, Tuple
+from numpy.random import seed
+
+# seed random number generator
+seed(1)
+
+
+class DataLoader:
+    """
+    read preprocessed pet and gt MIP data for training
+    """
+
+    def __init__(self, data_dir: str, ids_to_read: ndarray = None, shuffle=True, training: bool = True):
+        self.data_dir = data_dir
+        self.ids_to_read = ids_to_read
+        self.shuffle = shuffle
+        self.training = training
+
+    def get_batch_of_data(self):
+        """
+        data structure:
+        -- main directory
+        ------case Name:
+                -- pet.nii.gz
+                -- gt.nii.gz
+        --Given list of training and testing on .text files
+            -- train.text
+            -- valid.text
+        """
+
+        # check directory
+        self.directory_exist(self.data_dir)
+
+        # get all names of the directories under data_dir
+        case_ids = os.listdir(self.data_dir)
+
+        # store batch data
+        image_batch, ground_truth_batch = [], []
+
+        # if there are file in data dir
+        if not len(case_ids):
+            raise Exception("No files found in %s" % self.data_dir)
+
+        # else continue getting.reading the files
+        for get_id in list(case_ids):
+            if str(get_id) in list(self.ids_to_read):
+                try:
+                    # consider there four images in each folder name get_id:
+                    # e.g. : coronal (gt_1, pet_1) and sagittal  (gt_0, pet_0)
+                    current_dir = os.path.join(self.data_dir, str(get_id))
+                    # read sagittal and coronal as independent images
+                    pet_sagittla_coronal, gt_sagittal_coronal = self.get_nii_files_path(current_dir)
+
+                    # pet, normalization, standardization
+                    if len(pet_sagittla_coronal):  # if image is read
+                        pet_sagittla_coronal = self.data_normalization_standardization(pet_sagittla_coronal,
+                                                                                       z_score=True,
+                                                                                       z_score_include_zeros=False)
+
+                        gt_sagittal_coronal = self.data_normalization_standardization(gt_sagittal_coronal, threshold=True)
+
+                        # display or save samples
+                        # self.mip_show(pet=pet_sagittla_coronal, gt=gt_sagittal_coronal, identifier=str(get_id))
+
+                        # collect all images with case_id
+                        if not bool(len(image_batch)):  # if it is empty; first time
+                            image_batch = pet_sagittla_coronal
+                            ground_truth_batch = gt_sagittal_coronal
+                        else:
+                            image_batch = np.concatenate((image_batch, pet_sagittla_coronal), axis=0)
+                            ground_truth_batch = np.concatenate((ground_truth_batch, gt_sagittal_coronal), axis=0)
+                except:
+                    print('Not read %s' %(str(get_id)))
+
+        return [image_batch, ground_truth_batch]
+
+    @staticmethod
+    def directory_exist(dir_check: str = None) -> None:
+        """
+        :param dir_check:
+        """
+        if os.path.exists(dir_check):
+            #  print("The directory %s does exist \n" % dir_check)
+            pass
+        else:
+            raise Exception(
+                "Please provide the correct path to the processed data ! \n %s not found \n" % (dir_check))
+
+    @staticmethod
+    def mip_show(pet: ndarray = None, gt: ndarray = None, identifier: str = None) -> None:
+        """
+
+        :param pet:
+        :param gt:
+        :param identifier:
+        :return:
+        """
+        # consider axis 0 for sagittal and axis 1 for coronal views
+        fig, axs = plt.subplots(1, 4, figsize=(15, 15))
+        plt.title(str(identifier))
+        try:
+            pet = np.squeeze(pet)
+            gt = np.squeeze(gt)
+        except:
+            pass
+
+        axs[0].imshow(np.rot90(np.log(pet[0] + 1)))
+        axs[0].set_title('pet_project_on_axis_0')
+        axs[1].imshow(np.rot90(np.log(gt[0] + 1)))
+        axs[1].set_title('gt_project_on_axis_0')
+        axs[2].imshow(np.rot90(np.log(pet[1] + 1)))
+        axs[2].set_title('project_on_axis_1')
+        axs[3].imshow(np.rot90(np.log(gt[1] + 1)))
+        axs[3].set_title('gt_project_on_axis_1')
+        plt.show()
+
+    @staticmethod
+    def get_nii_files_path(data_directory: str) -> List[ndarray]:
+        """
+        read .nii or .nii.gz files from a given folder of path data_directory
+        :param data_directory:
+        :return:
+        """
+        # more than one .nii or .nii.gz is found in the folder the first will be returned
+        types = ('/*.nii', '/*.nii.gz')  # the tuple of file types
+        nii_paths = []
+        for files in types:
+            nii_paths.extend([i for i in glob.glob(str(data_directory) + files)])
+
+        pet, gt = [], []
+        if not len(nii_paths):  # if no file exists that ends wtih .nii.gz or .nii
+            # raise Exception("No .nii or .nii.gz found in %s dirctory" % data_directory)
+            pass
+        else:
+            # assuming the folder contains coronal mips: pet_1, gt_1, and sagittal mips: pet_0, gt_0,
+            pet_saggital, pet_coronal, gt_saggital, gt_coronal = [], [], [], []
+            for path in list(nii_paths):
+                # get the base name: means the file name
+                identifier_base_name = str(os.path.basename(path)).split('.')[0]
+                if "pet_sagittal" == str(identifier_base_name):
+                    pet_saggital = np.asanyarray(nib.load(path).dataobj)
+                    pet_saggital = np.expand_dims(pet_saggital, axis=0)
+
+                elif "pet_coronal" == str(identifier_base_name):
+                    pet_coronal = np.asanyarray(nib.load(path).dataobj)
+                    pet_coronal = np.expand_dims(pet_coronal, axis=0)
+
+                if "ground_truth_sagittal" == str(identifier_base_name):
+                    gt_saggital = np.asanyarray(nib.load(path).dataobj)
+                    gt_saggital = np.expand_dims(gt_saggital, axis=0)
+
+                elif "ground_truth_coronal" == str(identifier_base_name):
+                    gt_coronal = np.asanyarray(nib.load(path).dataobj)
+                    gt_coronal = np.expand_dims(gt_coronal, axis=0)
+
+            # concatenate coronal and sagita images
+            # show
+            pet = np.concatenate((pet_saggital, pet_coronal), axis=0)
+            gt = np.concatenate((gt_saggital, gt_coronal), axis=0)
+        return [pet, gt]
+
+    @staticmethod
+    def z_score(image: ndarray, include_zeros: bool = False):
+        """
+
+        :param image:
+        :param include_zeros:
+        :return:
+        """
+        # include zeros
+        if include_zeros:
+            image = (image - np.mean(image)) / (np.std(image) + 1e-8)
+        else:
+            # Don't include zeros
+            means = np.true_divide(image.sum(), (image != 0).sum())
+            stds = np.nanstd(np.where(np.isclose(image, 0), np.nan, image))
+            image = (image - means) / (stds + 1e-8)
+        return image
+
+    def data_normalization_standardization(self, data: ndarray, threshold: bool = False, z_score: bool = False,
+                                           z_score_include_zeros: bool = False,
+                                           min_max_scale: bool = False, log_transform: bool = False) -> List[ndarray]:
+        """
+        Data normalization and standardization function
+        :param data:
+        :param threshold:
+        :param z_score:
+        :param z_score_include_zeros:
+        :param min_max_scale:
+        :param log_transform:
+        :return:
+        """
+
+        if not isinstance(data, List):
+            data = np.array(data)
+
+        # groundtruh > 0 is 1 and <=0 is 0
+        if threshold:
+            data[data > 0] = 1
+
+        if z_score:
+            data = self.z_score(data, include_zeros=z_score_include_zeros)
+
+        if min_max_scale:
+            data = (data - min(data)) / (max(data) - min(data))
+
+        if log_transform:
+            data = np.log(data + 1)
+
+        return data
+
+
+if __name__ == '__main__':
+    # for Example
+    print("data_loader for preprocessed coronal and sagittal MIPs, pet, and gt")
+    data_dir = "../data/vienna_default_MIP_dir/"
+    ids_to_read = os.listdir(data_dir)
+
+    data_loader = DataLoader(data_dir=data_dir, ids_to_read=ids_to_read)
+    loaded_data = data_loader.get_batch_of_data()
+    print(np.array(loaded_data).shape)