numpy를 이용한 Slicing 정리.

#Slicing
 
nums = range(5) # range is a built-in function that creates a list of integers
print nums      #prints "[0,1,2,3,4]"
print nums[2:4] #prints "[2,3]"
print nums[2:]  #pirnts "[2,3,4]"
print nums[:2]  #prints "[0,1]"
print nums[:]   #prints "[0,1,2,3,4]"
print nums[:-1] #prints "[0,1,2,3]"
nums[2:4] = [8,9] #Assign a new sublist to a slice
print nums      #prints "[0,1,8,9,4]"
 
#Indexing, Slicing, Iterating
 
import numpy as np
 
a = np.array([1,2,3,4,5])
# array([1, 2, 3, 4, 5])
 
a[1:3]
# array([2, 3])
 
a[-1]
# 5
 
a[0:2] = 9
 
a   #array([9, 9, 3, 4, 5])
 
#################################
 
b = np.array([[1,2,3,4],[5,6,7,8],[9,10,11,12]])
# array([ 1, 2, 3, 4],
#       [ 5, 6, 7, 8],
#       [ 9, 10, 11, 12]])
 
b[:, 1]
# array ([ 2, 6, 10])
 
b[-1]
# array([9, 10, 11, 12])
 
b[-1, :]
# array([9,10,11,12])
 
b[0:2, :]
#array ([[1,2,3,4],
#       [5,6,7,8]])