在Pandas DataFrame中创建一个新列，并将所有单元格设置为默认数组

Question

I'm trying to build a DataFrame where one of the columns represents a vector. This is the part of code I'm having trouble with:

tweets = pd.DataFrame(train_tweets)
tweets["LangClass"] = "und"
tweets["LangVec"] = pd.Series[[0,0,0,0,0,0,0,0,0,0]]

train_tweets is an incoming DataFrame with only two columns, and I want to add a third and fourth column, LangClass and LangVec. The values in LangVec will be updated element by element.

I had it working by using a for loop to iterate through the DataFrame and setting each value of LangVec to the desired vector, but that seems to be a very slow approach.

Thanks for any suggestions!

Answer 1

I think the best is create list of tuples or list of lists and then call DataFrame contructor:

L = []
for x in iterator:
    first_val = some_code_for_count_val
    second_val =  some_code_for_count_val
    L.append((first_val, second_val)) 

df1 = pd.DataFrame(L, columns = ['LangClass', 'LangVec'])

Last join to original DataFrame:

df = df.join(df1)