#This is our usual function where we have to define a name for the function
def func(x,y):
return(x+y)
func(2,3)5Lambda
Lambda is an important function/operator to create anonymous in-line functions in pyhton.
Basic syntax:
lamda arguments: expression
#Lambda function
add=lambda x,y:x+y
add(2,3)5lambda functions can be used in place of a iterator when sorting – this allows for selecting the column or the varible according to which sorting has to be done
import numpy as np
np.random.seed(42)
a1=np.random.choice(10,5,replace=False)
file_list=[]
for i in a1:
file_list.append('{0}-{1}'.format('Filename',i))print(file_list)['Filename-8', 'Filename-1', 'Filename-5', 'Filename-0', 'Filename-7']file_list=sorted(file_list, key=lambda x:x.split('-')[-1])file_list['Filename-0', 'Filename-1', 'Filename-5', 'Filename-7', 'Filename-8']Map
When you want to have multiple outputs for the functions but do not want to write a for all explicitly you can use map function for pseeding things up
def square(x):
return(x**2)
print(a1)
ans=[square(i) for i in a1]
print(ans)[8 1 5 0 7]
[64, 1, 25, 0, 49]#Using map function
map(square,a1)<map at 0x7f85058e5eb8>#You'd have to first converrt it to list
list(map(square,a1))[64, 1, 25, 0, 49]Combining the two:
a=np.random.choice(10,5,replace=False)
b=np.random.choice(50,5,replace=False)
result=map(lambda x,y:x*y,a,b)
print(a)
print(b)
print(np.asarray(list(result)))[0 1 8 5 3]
[36 16 4 9 45]
[ 0 16 32 45 135]