leave one out method for multiple csv files in python

Question

I have a data set with multiple CSV files (12 files)... Each file belongs to a person. I've used a neural network for modeling each file and now I want to use the Leave-One-Out method and leave one file for the test... How could I do this in python?

Here is my code for one file (In this code data is split to test and train for learning one file):

from keras.models import Sequential
from keras.layers import Dense
from sklearn.metrics import accuracy_score
from keras import layers
from sklearn.preprocessing import RobustScaler
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt

from sklearn.model_selection import train_test_split

def get_dataset():
  data = pd.read_csv("file1.csv")
  X=data.iloc[0:, 0:50]
  y = data.iloc[0:, 50:]
  
  return X, y

# get the model
def get_model(n_inputs, n_outputs):
  model = Sequential()
  model.add(Dense(20, input_dim=n_inputs, kernel_initializer='he_uniform', activation='relu'))
  model.add(layers.Dense(16, activation='relu'))
  model.add(layers.Dense(16, activation='relu'))
  model.add(Dense(n_outputs, activation='sigmoid'))
  model.compile(loss='binary_crossentropy', optimizer='adam')
  return model

Answer 1

You could try something like this.

import glob

def get_dataset():
  csv_list = glob.glob("path_to_csvs/*.csv")
  csv_test = csv_list.pop(random.randint(0,len(csv_list)-1) # remove one random element from csv list and return it
  data_test = pd.read_csv(csv_test)
  data_train = pd.concat([pd.read_csv(f) for f in csv_list])
  .
  .
  .
  return X, y

Answer 2

It is possible this way you may shuffles or manage it as index.

[ Sample ]:

import matplotlib.pyplot as plt
import os
import tensorflow as tf
import tensorflow_io as tfio

import pandas as pd
from sklearn.preprocessing import RobustScaler


"""""""""""""""""""""""""""""""""""""""""""""""""""""""""
: Variables
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""
list_label = [ ]
list_Image = [ ]
n_books = 12
start = 1
limit = n_books

PATH = os.path.join('F:\\datasets\\downloads\\Actors\\train\\Pikaploy', '*.tif')
PATH_2 = os.path.join('F:\\datasets\\downloads\\Actors\\train\\Candidt Kibt', '*.tif')
files = tf.data.Dataset.list_files(PATH)
files_2 = tf.data.Dataset.list_files(PATH_2)

list_file = []
list_file_actual = []
list_label = []
list_label_actual = [ 'Pikaploy', 'Pikaploy', 'Pikaploy', 'Pikaploy', 'Pikaploy', 'Candidt Kibt', 'Candidt Kibt', 'Candidt Kibt', 'Candidt Kibt', 'Candidt Kibt' ]
for file in files.take(15):
    image = tf.io.read_file( file )
    image = tfio.experimental.image.decode_tiff(image, index=0)
    list_file_actual.append(image)
    image = tf.image.resize(image, [32,32], method='nearest')
    list_file.append(image)
    list_label.append(1)
    
for file in files_2.take(18):
    image = tf.io.read_file( file )
    image = tfio.experimental.image.decode_tiff(image, index=0)
    list_file_actual.append(image)
    image = tf.image.resize(image, [32,32], method='nearest')
    list_file.append(image)
    list_label.append(9)

"""""""""""""""""""""""""""""""""""""""""""""""""""""""""
: Callback
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""
class custom_callback(tf.keras.callbacks.Callback):
    def on_epoch_end(self, epoch, logs={}):
        if( logs['accuracy'] >= 0.97 ):
            self.model.stop_training = True
    
custom_callback = custom_callback()
    

"""""""""""""""""""""""""""""""""""""""""""""""""""""""""
: Functions
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""
def get_dataset():
    list_label = [ ]
    list_Image = [ ]
    datasets = [ ]

    scale_column = ['Image']
    scale_column_label = ['Label']

    for i in range( n_books ) :
        variables_1 = pd.read_excel('F:\\temp\\Python\\excel\\Book ' + str( i + 1 ) + '.xlsx', index_col=None, header=[0])
    
        for i in range( variables_1[scale_column].to_numpy().shape[0] ) :
            image = tf.io.read_file(  variables_1[scale_column].to_numpy()[i][0] )
            image = tfio.experimental.image.decode_tiff(image, index=0)
            image = tf.image.resize(image, [32,32], method='nearest')
            label = variables_1[scale_column_label].to_numpy()[i][0]
        
            list_Image.append( image )
            list_label.append( label )
    
        dataset_1 = tf.data.Dataset.from_tensor_slices((tf.constant(tf.cast(list_Image, dtype=tf.int64), shape=(len( list_Image ), 1, 32, 32, 4), dtype=tf.int64),tf.constant(list_label, shape=(len( list_label ), 1, 1), dtype=tf.int64)))
        datasets.append( dataset_1 )
    
    return datasets

"""""""""""""""""""""""""""""""""""""""""""""""""""""""""
: Model Initialize
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""
model = tf.keras.models.Sequential([
    tf.keras.layers.InputLayer(input_shape=( 32, 32, 4 )),
    tf.keras.layers.Normalization(mean=3., variance=2.),
    tf.keras.layers.Normalization(mean=4., variance=6.),
    tf.keras.layers.Dense(256, activation='relu'),
    tf.keras.layers.Reshape((256, 32 * 32)),
    tf.keras.layers.Bidirectional(tf.keras.layers.LSTM(196, return_sequences=True, return_state=False)),
    tf.keras.layers.Bidirectional(tf.keras.layers.LSTM(196)),
    tf.keras.layers.Flatten(),
    tf.keras.layers.Dense(192, activation='relu'),
    tf.keras.layers.Dense(2),
])

"""""""""""""""""""""""""""""""""""""""""""""""""""""""""
: Callback
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""
class custom_callback(tf.keras.callbacks.Callback):
    def on_epoch_end(self, epoch, logs={}):
        if( logs['accuracy'] >= 0.97 ):
            self.model.stop_training = True
    
custom_callback = custom_callback()

"""""""""""""""""""""""""""""""""""""""""""""""""""""""""
: Optimizer
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""
optimizer = tf.keras.optimizers.Nadam(
    learning_rate=0.000001, beta_1=0.9, beta_2=0.999, epsilon=1e-07,
    name='Nadam'
)

"""""""""""""""""""""""""""""""""""""""""""""""""""""""""
: Loss Fn
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""                               
lossfn = tf.keras.losses.SparseCategoricalCrossentropy(
    from_logits=False,
    reduction=tf.keras.losses.Reduction.AUTO,
    name='sparse_categorical_crossentropy'
)

"""""""""""""""""""""""""""""""""""""""""""""""""""""""""
: Model Summary
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""
model.compile(optimizer=optimizer, loss=lossfn, metrics=['accuracy'] )

"""""""""""""""""""""""""""""""""""""""""""""""""""""""""
: Training
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""
range_value = tf.range(start, limit, delta=1, dtype=tf.int32, name='range')
shuffle = tf.random.shuffle( range_value, seed=10, name='shuffle' )

datasets = get_dataset()
print( shuffle )

for i in range( int( n_books - 1 ) ) :
    history = model.fit( datasets[shuffle[i]], batch_size=100, epochs=50, callbacks=[custom_callback] )

Answer 3

I haven't used tensorflow but in Python when I want to find the optimum k for a k-NN classifier in sklearn using the leave-one-out method, I use the following:

import pandas as pd
from sklearn.neighbors import KNeighborsClassifiercode

def single_case_classifier(training_df, target_group, ix, k):
'''Returns the target_group for the omitted index ix in the training_df using k-NN classifier'''

# Create a classifier instance to do k-nearest neighbours
myClassifier = KNeighborsClassifier(n_neighbors = k,
                                   metric = 'euclidean',
                                   weights = 'uniform')

# Apply aClassifer to all data points except index ix
myClassifier.fit(training_df.drop(ix, axis='index'),
                 target_group.drop(ix))

# Return the class predicted by the trained classifier
# Need to predict on list of training_df.loc[ix] as predict
# expects list/array

return myClassifier.predict([training_df.loc[ix]])[0]

Then import your data and separator the training columns and the group column, for example:

training_data_df = data_df[['#training_columns']]
group_values = data_df['#group_column']

And finally, to implement the function to find the best k value, we count to see how many correct matches for each data point there is for each k value and select the k value with the highest count. If two k values are tied with the highest correct count then I choose the smaller of the two k values

for k in range(1,8):
    print('{}\t{}'.format(k,
                          list([single_case_classifier(training_data_df,
                                                       group_values,
                                                       i,
                                                       k)
                               for i in training_data_df.index] == group_values).count(True)))

Since you have the data in different files, this may work if you can combine the data into one dataframe. If your data is not setup like that then I hope this gives some idea of how a leave-one-out method is implemented in Python. Best of luck.