is : and :: the same in python slice
a[-1] # last item in the array
a[-2:] # last two items in the array
a[:-2] # everything except the last two itemsis : and :: the same in python slice
a[-1] # last item in the array
a[-2:] # last two items in the array
a[:-2] # everything except the last two itemspython slice
# array[start:stop:step]
# start = include everything STARTING AT this idx (inclusive)
# stop = include everything BEFORE this idx (exclusive)
# step = (can be ommitted) difference between each idx in the sequence
arr = ['a', 'b', 'c', 'd', 'e']
arr[2:] => ['c', 'd', 'e']
arr[:4] => ['a', 'b', 'c', 'd']
arr[2:4] => ['c', 'd']
arr[0:5:2] => ['a', 'c', 'e']
arr[:] => makes copy of arrpython slice
a[start:stop] # items start through stop-1
a[start:] # items start through the rest of the array
a[:stop] # items from the beginning through stop-1
a[:] # a copy of the whole arraypython3 slice
# array[start:stop:step]
# start = include everything STARTING AT this idx (inclusive)
# stop = include everything BEFORE this idx (exclusive)
# step = (can be committed) difference between each idx in the sequence
arr = ['a', 'b', 'c', 'd', 'e']
arr[2:] => ['c', 'd', 'e']
arr[:4] => ['a', 'b', 'c', 'd']
arr[2:4] => ['c', 'd']
arr[0:5:2] => ['a', 'c', 'e']
arr[:] => makes copy of arrarray slicing python
#slicing arrays:
#generic sampling is done by
#arr[start:end] -> where start is the starting index and end is ending idx
>>> import numpy as np
>>> arr = np.array([1,2,3,4,5])
>>> print(arr[1:5]) #starting idx 1 to ending index 4
[2 3 4 5]#it will print from starting idx to ending idx-1
#if you leave the ending index blank it will print all
#from the starting index till end
>>> arr = np.array([2,6,1,7,5])
>>> print(arr[3:])
[7 5]
>>> print(arr[:3]) #if you leave the starting index blank it will print from 0 index to the ending idx-1
[2 6 1]
>>> print(arr[:])
[2 6 1 7 5]
#leaving both the index open will print the entire array.
##########STEP slicing########
#if you want to traverse by taking steps more than 1
#we use step slicing in that case
#syntax for step slicing is : arr[start:end:step]
>>> arr = np.array([2,6,1,7,5,10,43,21,100,29])
>>> print(arr[1:8:2])#we have taken steps of two
[ 6 7 10 21]python slice operator
string = 'string_text'
beginning = 0 # at what index the slice should start.
end = len(string) # at what index the slice should end.
step = 1 # how many characters the slice should go forward after each letter
new_string = string[beginning:end:step]
# some examples
a = 0
b = 3
c = 1
new_string = string[a:b:c] # will give you: str
# ____________________________________________
a = 2
b = len(string) - 2
c = 1
new_string = string[a:b:c] # will give you: ring_teCopyright © 2021 Codeinu
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