I am getting bit confused after seeing the output of following Python program:
t = [0,1,2]
t[2:].append(t[0])
print(t)
OUTPUT:
[0,1,2]
Here, I have taken a list [0,1,2]. Why is the output [0,1,2], and not [0,1,0]? Please someone help me to clear my doubt.
It is because t[2:] creates another list, and you are appending to that list, but in the end you are printing the original list t
To give some light:
t is a list object, and when you do t[2:], you are creating a new list object based on the first one. Then, you append to this new object a value and, since you don't store that new object in any variable, the object is lost.
Finally, you are just printing your original, which has not changed, list.
Try this:
new_t = t[2:] # New object with your slice
new_t.append(t[0]) # Appending a value of your old list to this new created list
print(new_t) # Printing the new list
This line of code, do nothing:
t[2:].append(t[0])
For desired result use:
t = [0,1,2]
t2 = t[:2] # we only need 1st and 2nd value from t
t2.append(t[0]) # append 1st value of t in the last of t2 to generate the desired list
print(t2) # print t2 (the desired list)
or
t = [0,1,2]
t[-1] = t[0] # update the last element of list, same as first element
print(t) # print updated list having desired answer
t[2:]is a slice, which means it is a copy of part of the list.tstill holds your original list. Altering the copy doesn't affect the original.