Question

For Python, I am a little confused on the use of reduce,map, and lambda. My assignment wants me to not use .join() and write a SINGLE LINE function to join each letter in a list with another string.(See problem below).

Using reduce, map, and lambda, write the single-expression function myJoin(L, sep) that takes a non-empty list L and a string sep, and without calling sep.join(L), works roughly the same as that returning a single string with the values in L separated by the sep. So myJoin(a',b,'c], - returns 'a-b-c Unlike sep.join(L), your function must work even if L contains non-strings. So: myJoin([1, 2,3], @@) returns '1@@2@@3 Remember that you may not call join, and your solution must be only one python expression

Answer 1

Here is the code for adding list of characters to string without using join.

if the version of python is above 3 we have to import reduce function or else no need to import it.

from functools import reduce #importing reduce since my python version is 3.8
def myJoin(L,sep): #function for list to string changing
    return(reduce(lambda x,y:x+y,L) )#single line reduce and lambda function and returning the string
L=['r','e','d','u','c','e','l','a','m','d','a','u','s','e'] //taking list
print(myJoin(L,',')) //calling the function and printing the string which is return from function.

Code and ouptut:

from functools import reduce def myJoin (L, sep): return (reduce (lambda x, y:xty,L)) LFI'r,'e,"d',,c,e,l,a, 'm',"d,'a,u',s,e'] print (myJoin (L,',)) reducelamdause

How reduce function works is lets assume a small list['h','e','l','l',o'] now if we pass this list to lambda function which contains reduce it will perform rolling computation means first reduce function will take 'h','e' and concatenates to 'he' and then it will take 'he' and 'l' and concatenates to 'hel' after that 'hel','l' concatenates to'hell' finally 'hell','o' will concatenate and return the string 'hello'.

lets assume one more example if we have a list containing 5 elements [1,2,3,4,5] if we want to product those elements then we can use reduce it will take first 1 & 2 and computes 1*2=2 and then it will take the result of first one and 3 and computes the result i.e 2*3=6 after that 6*4=24 and then 24*5=120.

Note : If you have any queries please post a comment thanks a lot.