Oops, returning with the column question before the variable. Example I'm seeing in python in neural recurring.
arr = arr[:n_batches * batches_size]
What does :n_batches mean?
: column in front of variable
1
asked by anonymous 01.03.2018 / 01:53
1 answer
1
This is called slice . With it you can access a slice of an object that is iterable. For example, doing lista[1:5] you would be accessing items from 1 to 4 (5 represents the first index not included in the slice). When you omit the first value, the slice will be considered from the beginning of the iterator. That is, lista[:5] is the equivalent of lista[0:5] . If the second value is omitted, it will be considered until the end of it. That is, doing lista[5:] would get all values from index 5 to the end. If both numbers are omitted, it will take the iterator from start to finish, making a race copy of your object.
In your case,
arr = arr[:n_batches * batches_size]
You are accessing the iterable arr from the beginning to the result of the n_batches * batches_size multiplication. The equivalent would be:
arr = arr[0:n_batches * batches_size]
See some other examples:
lista = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
print(lista[1:5]) # [1, 2, 3, 4]
print(lista[:5]) # [0, 1, 2, 3, 4]
print(lista[1:]) # [1, 2, 3, 4, 5, 6, 7, 8, 9]
print(lista[:]) # [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
01.03.2018 / 02:09