Append to Series in python/pandas not working

The Series.append documentation states that append rows of other to the end of this frame, returning a new object.

The examples are a little confusing as it appears to show it working but if you look closely you'll notice they are using interactive python which prints the result of the last call (the new object) rather than showing the original object.

The result of calling append is actually a brand new Series.

In your example you would need to assign q each time to the new object returned by .append:

q = pd.Series([])
while i < len(other array):
    diff = some int value
    a = pd.Series([diff], ignore_index=True)
    # change of code here
    q = q.append(a)
    i+=1

The append method doesn't work in-place. Instead, it returns a new Series object. So it should be:

q = q.append(a)

Hope it helps!