tensorflow dataset code example

Example 1: what is tf.data.dataset.reduce()

# import tensorflow 
import tensorflow as tf 
  
# using tf.data.Dataset.reduce() method 
data = tf.data.Dataset.from_tensor_slices([1, 2, 3, 4, 5]) 
  
print(data.reduce(0, lambda x, y: x + y).numpy())
# it return the summation of all element
# 0 + (1+2+3+4+5)
>> 15
# if we use 1 instead of 0 then after summation of all array 
# we also sum this extra 1 , so the result will be ---
print(data.reduce(1, lambda x, y: x + y).numpy())
# 1+(1+2+3+4+5)
>>16
# import tensorflow 
import tensorflow as tf 
  
# using tf.data.Dataset.reduce() method 
data = tf.data.Dataset.from_tensor_slices([[5, 10], [3, 6]]) 
  
print(data.reduce(0, lambda x, y: x * y).numpy())
# [5*3*0 10*6*0]
>>[0 0]
print(data.reduce(1, lambda x, y: x * y).numpy())
# [5*3*1 10*6*1]
>>[15 60]
# so what about this example?
print(data.reduce(2, lambda x, y: x * y).numpy())
# as you expect!!
# [5*3*2 10*6*2]
>>[30 120]

Example 2: tf.data.Dataset select files with labels filter

dataset = train_data.filter(lambda x,y: tf.reduce_all(tf.not_equal(y, [0,1,2]))).batch(200)