The learning objectives of this section are:
import numpy as np
arr = np.array([[1,2,3,4],[5,6,7,8], [9,10,11,12]])
print(arr)
OUTPUT:
[[ 1 2 3 4]
[ 5 6 7 8]
[ 9 10 11 12]]
print(arr.shape)
OUTPUT:
(3,4)
sh_arr=arr.reshape(12,1)
sh_arr
OUTPUT:
array([[ 1],
[ 2],
[ 3],
[ 4],
[ 5],
[ 6],
[ 7],
[ 8],
[ 9],
[10],
[11],
[12]])
import numpy as np
arr = np.array([[1,2,3,4],[5,6,7,8]])
arr
OUTPUT:
array([[1, 2, 3, 4],
[5, 6, 7, 8]])
arr.resize(6,6,refcheck=False)
arr
OUTPUT:
array([[1, 2, 3, 4, 5, 6],
[7, 8, 0, 0, 0,0],
[0, 0, 0, 0, 0,0],
[0, 0, 0, 0, 0,0],
[0, 0, 0, 0, 0,0],
[0, 0, 0, 0, 0,0]])
np.hstack()
and n.vstack()
Stacking is done using the np.hstack()
and np.vstack()
methods. For horizontal stacking, the number of rows should be the same, while for vertical stacking, the number of columns should be the same.
a = np.array([1, 2, 3,4,5])
b = np.array([4, 5, 6,7,8])
c = np.array([4, 5, 6])
np.hstack([a,b,c])
OUTPUT:
array([1, 2, 3, 4, 5, 4, 5, 6, 7, 8, 4, 5, 6])
a = np.array([1, 2, 3])
b = np.array([4, 5, 6])
c = np.array([4, 5, 6])
np.vstack((a,b,c))
OUTPUT:
array([[1, 2, 3],
[4, 5, 6],
[4, 5, 6]])
a=np.array([[1,2,3,4],[5,6,7,8]])
a
OUTPUT:
array([[1, 2, 3, 4], [5, 6, 7, 8]])
a.shape
OUTPUT:
(2,4)
flat_array = a.flatten()
flat_array
OUTPUT:
array([1, 2, 3, 4, 5, 6, 7, 8])
flat_array.shape
OUTPUT:
(8,)
arr = np.array([[1,2,3,4],[5,6,7,8]])
arr
OUTPUT:
array([[1, 2, 3, 4],
[5, 6, 7, 8]])
arr.shape
OUTPUT:
(2,4)
arr1= arr.transpose(1,0)
arr1.shape
OUTPUT:
(4,2)
arr1
OUTPUT:
array([[1, 5],
[2, 6],
[3, 7],
[4, 8]])
arr = np.arange(10).reshape((5,2))
arr
OUTPUT:
array([[0, 1],
[2, 3],
[4, 5],
[6, 7],
[8, 9]])
np.sum(arr)
OUTPUT:
45
print(np.sum(arr,axis =0)) ## rows
OUTPUT:
[20 25]
print(np.sum(arr,axis =1))
OUTPUT:
[ 1 5 9 13 17]
a = np.arange(10)
a
OUTPUT:
array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
# condition , yes , no
b = np.where(a > 5, a, 10*a)
b
OUTPUT:
array([ 0, 10, 20, 30, 40, 50, 6, 7, 8, 9])
arr = np.array([3,4,1,5,9,6,2])
print(arr)
arr_sorted = sorted(arr,reverse=False)
print(arr_sorted)
OUTPUT:
[3 4 1 5 9 6 2]
[1, 2, 3, 4, 5, 6, 9]
array1 = np.array([10,20,30,40,50])
array2 = np.array([2])
print(array1/array2)
OUTPUT:
[ 5. 10. 15. 20. 25.]
array1 = np.array([[10,20,30,40,50],[10,20,30,40,50]])
array2 = np.array([1,2,3,4,5])
print(array1+array2)
OUTPUT:
[[11 22 33 44 55]
[11 22 33 44 55]]
# Python Program to find the area of triangle
a = 5
b = 6
c = 7
# Uncomment below to take inputs from the user
# a = float(input('Enter first side: '))
# b = float(input('Enter second side: '))
# c = float(input('Enter third side: '))
# calculate the semi-perimeter
s = (a + b + c) / 2
# calculate the area
area = (s*(s-a)*(s-b)*(s-c)) ** 0.5
print('The area of the triangle is %0.2f' %area)