MLPQNA model

tomo_challenge/classifiers/mlpqna.py

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+"""
+This is an example tomographic bin generator using a random forest.
+
+Every classifier module needs to:
+ - have construction of the type 
+       __init__ (self, bands, options) (see examples below)
+ -  implement two functions: 
+        train (self, training_data,training_z)
+        apply (self, data).
+ - define valid_options class varible.
+
+See Classifier Documentation below.
+"""
+
+from .base import Tomographer
+import numpy as np
+from sklearn.neural_network import MLPClassifier as mlp
+from sklearn.preprocessing import StandardScaler
+
+
+
+
+class mlpqna(Tomographer):
+    """ Random Forest Classifier """
+
+    # valid parameter -- see below
+    valid_options = ['bins']
+    # this settings means arrays will be sent to train and apply instead
+    # of dictionaries
+    wants_arrays = True
+
+    def __init__ (self, bands, options):
+        """Constructor
+
+        Parameters:
+        -----------
+        bands: str
+          string containg valid bands, like 'riz' or 'griz'
+        options: dict
+          options come through here. Valid keys are listed as valid_options
+          class variable. 
+
+        Note:
+        -----
+        Valiad options are:
+            'bins' - number of tomographic bins
+
+        """
+        self.bands = bands
+        self.opt = options
+
+    def train (self, training_data, training_z):
+        """Trains the classifier
+
+        Parameters:
+        -----------
+        training_data: numpy array, size Ngalaxes x Nbands
+          training data, each row is a galaxy, each column is a band as per
+          band defined above
+        training_z: numpy array, size Ngalaxies
+          true redshift for the training sample
+
+        """
+
+        n_bin = self.opt['bins']
+        print("Finding bins for training data")
+        # Now put the training data into redshift bins.
+        # Use zero so that the one object with minimum
+        # z in the whole survey will be in the lowest bin
+        training_bin = np.zeros(training_z.size)
+
+        # Find the edges that split the redshifts into n_z bins of
+        # equal number counts in each
+        p = np.linspace(0, 100, n_bin + 1)
+        z_edges = np.percentile(training_z, p)
+
+        # Now find all the objects in each of these bins
+        for i in range(n_bin):
+            z_low = z_edges[i]
+            z_high = z_edges[i + 1]
+            training_bin[(training_z > z_low) & (training_z < z_high)] = i
+
+        # for speed, cut down to 5% of original size
+        cut = np.random.uniform(0, 1, training_z.size) < 0.05
+        training_bin = training_bin[cut]
+        training_data = training_data[cut]
+
+        # Can be replaced with any classifier
+        actFunc ="tanh"
+        decayVal =0.1
+        h1Layers = 2
+        h1LayerNodes = 2* training_data.shape[1] -1
+        h2LayerNodes = training_data.shape[1]+1
+        trainEpochs = 20000
+        seed = 3214234
+        tolerance = 1e-20
+        verboseFlag = True
+        warmFlag = False
+        maxFun = 30000        
+        classifier= mlp(activation=actFunc, solver='lbfgs', alpha=decayVal, hidden_layer_sizes=(h1LayerNodes, h2LayerNodes), max_iter=trainEpochs, random_state=seed, tol=tolerance, verbose=verboseFlag, warm_start=warmFlag, max_fun=maxFun)
+        scaler = StandardScaler()
+        # Fit only to the training data
+        scaler.fit(training_data)
+        # Now apply the transformations to the data:
+        X_norm_train = scaler.transform(training_data)
+
+        print("Fitting classifier")
+        # Lots of data, so this will take some time
+        classifier.fit(X_norm_train, training_bin)
+        self.scaler=scaler
+        self.classifier = classifier
+        self.z_edges = z_edges
+
+
+    def apply (self, data):
+        """Applies training to the data.
+
+        Parameters:
+        -----------
+        Data: numpy array, size Ngalaxes x Nbands
+          testing data, each row is a galaxy, each column is a band as per
+          band defined above
+
+        Returns: 
+        tomographic_selections: numpy array, int, size Ngalaxies
+          tomographic selection for galaxies return as bin number for 
+          each galaxy.
+        """
+        X_norm_data = self.scaler.transform(data)
+        tomo_bin = self.classifier.predict(X_norm_data)
+        return tomo_bin
+