Python 只在新的 csv 文件中写入最后一行

Question

I have only last line written in a new csv file.

f = open(r'dataset.csv', encoding="utf8")
data = f.readlines()

tagged_list = []

for line in data:
    tokens = nltk.word_tokenize(line)
    tagged = nltk.pos_tag(tokens)
    adj = [word for word,pos in tagged \
            if (pos == 'JJ' or pos == 'JJR' or pos == 'JJS')]
    downcased = [x.lower() for x in adj]
    joined = " ".join(downcased).encode('utf-8')
    into_string = str(adj)

output = open("out.csv", "wb")
output.write(joined)
output.close()

When I change output = open("out.csv", "a") or output = open("out.csv", "r") I m getting error

Traceback (most recent call last):
  File "nl.py", line 21, in <module>
    output.write(joined)
TypeError: write() argument must be str, not bytes

How can I make it write all the lines one after another and not only the last line.

Answer 1

Open both files, and write the lines as you generate them (untested):

with open('dataset.csv', encoding='utf8') as data:
    with open('out.csv','w',encoding='utf8') as output:
        for line in data:
            tokens = nltk.word_tokenize(line)
            tagged = nltk.pos_tag(tokens)
            adj = [word for word,pos in tagged
                   if (pos == 'JJ' or pos == 'JJR' or pos == 'JJS')]
            downcased = [x.lower() for x in adj]
            joined = " ".join(downcased) + '\n'
            output.write(joined)