将for循环的输出存储到单个变量中

Question

I have a for loop that retrieves bigram data of a page of text from an SQLite3 database.

def bigram_db():
cursr.execute("SELECT * FROM trainedGrammar")
data = cursr.fetchall()
for data in data:
    element = data
    txt = element[0] #fetch first element of list
    txt += txt
return txt

I tried using txt += txt but this only gives me a single paragraph worth bigram data when I tried to print cache outside the function bigram_db(). So how do I store all of the bigram data that is going to be output by the for loop, which can be accessed outside of the for loop and then when I print it, I want the entire bigram data of the database to be available.

Answer 1

You don't need to execute fetchall() , you can iterate directly on the cursor. And you cannot use the same variable txt for two purposes; in the loop, the line txt = element[0] overwrites its old value.

Your function should look like this:

def bigram_db():
    cursr.execute("SELECT * FROM trainedGrammar")
    txt = ""
    for row in cursr:
        txt += row[0]
    return txt

Or without a for loop:

def bigram_db():
    cursr.execute("SELECT * FROM trainedGrammar")
    return "".join([row[0] for row in cursr])