使用 python (PANDA) 在 csv 文件中追加一行

Question

As the title suggests I am trying to add a row to an already existing csv file created in python using pandas with: df.to_csv("dataframe.csv", index=False, header=True) , and looking around the internet I found this method:

df = pd.DataFrame([], columns=[f"{name}", f"{usr}", f"{passw}"])
df.to_csv("dataframe.csv", mode="a", header=False)

but when I look at the csv file nothing happens. Am I doing something wrong? I am going to include the entire function even though I don't think it matters that much

# Takes the user input and appends it to the csv file (this is where I have the problem)
def usr_input():
    name = input("Website name: ")
    usr = input("Email or username: ")
    passw = input("Password: ")

    df = pd.DataFrame([], columns=[f"{name}", f"{usr}", f"{passw}"])
    df.to_csv("dataframe.csv", mode="a", header=False)

    flag = input("Add another one? (y/n): ")
    if flag == "y":
        usr_input()
    else:
        quit()

This is where I create the csv file:

def init():
    if not os.path.isfile("dataframe.csv"):
        df = pd.DataFrame([], columns=["Name", "Email / Username", "Password"])
        df.to_csv("dataframe.csv", index=False, header=True)
    else:
        usr_input()

Answer 1

Found the answer! I just needed to use the loc[] function:

data = [f"{name}", f"{usr}", f"{passw}"]
df.loc[len(df)] = data
df.to_csv("dataframe.csv", index=False)