How to add item last and remove first item in python dataframe?

Question

My dataframe is like this:

data = {
  "a": [420, 380, 390],
  "b": [50, 40, 45]
}

df = pd.DataFrame(data)

I want to add new item at the end of this dataframe, and remove the first item. I mean cont will be 3 each addition.

New item add

{"a": 300, b: 88}

and last stuation will be:

data = {
  "a": [380, 390, 300],
  "b": [40, 45, 88]
}

Is there a short way to do this?

Answer 1

Try this:

dct = {"a": 300, "b": 88}
df_new = df.append(dct, ignore_index=True).drop(0, axis=0).reset_index(drop=True)
print(df_new)

Output:

     a   b
0  380  40
1  390  45
2  300  88