将 for 循环中的列表写入 csv

Question

我编写了一个循环遍历 CSV 以获得如下列表的循环：

[t1, s1]
[t2, s2]
[t3, s3]

等等4000次。现在我需要将它们写入一个新的 CSV 文件，它们将在其中填充 2 个字段并用逗号分隔。当我输入这个时，我只得到最后一个循环的最后一个列表，并且在一个单元格中有一个字符。

def sentiment_analysis():
    fo = open("positive_words.txt", "r")
    positive_words = fo.readlines()
    fo.close()
    positive_words = map(lambda positive_words: positive_words.strip(), positive_words)
    fo = open("negative_words.txt", "r")
    negative_words = fo.readlines()
    fo.close()
    negative_words = map(lambda negative_words: negative_words.strip(), negative_words)
    fo = open("BAC.csv", "r")
    data = fo.readlines()
    fo.close()
    data = map(lambda data: data.strip(), data)
    x1 = 0 #number of bullish
    x2 = 0 #number of bearish
    x3 = 0 #number of unknown
    for info in data:
        data_specs = info.split(',')
        time_n_date = data_specs[0]
        sentiment = data_specs[2]
        '''Possibly precede with a nested for loop for data_specs???'''
        if sentiment == 'Bullish':
            '''fo.write(time + ',' + 'Bullish' + '\n')'''
        elif sentiment == 'Bearish':
            ''' fo.write(time + ',' + 'Bearish' + '\n')'''
        else:
            x3 += 1
            positive = 0
            negative = 0
            content_words = data_specs[1].split()
            for a in positive_words:
                for b in content_words:
                    if (a == b):
                        positive = positive + 1
            for c in negative_words:
                for d in content_words:
                    if (c == d):
                        negative = negative + 1
            if positive > negative:
                '''fo.write(time + ',' + 'Bullish' + '\n')'''
                sentiment = 'Bullish'
            elif positive < negative:
                sentiment = 'Bearish'
            else:
                sentiment = 'Neutral'
        bac2data = [time_n_date, sentiment]
        print bac2data
        fo = open("C:\Users\Siddhartha\Documents\INFS 772\Project\Answer\BAC2_answer.csv", "w")
        for x in bac2data:
            w = csv.writer(fo, delimiter = ',')
            w.writerows(x)
        fo.close()

我的 for 循环没有遍历所有内容。

Answer 1

在您的代码中 bac2data = [time_n_date, sentiment] 创建一个包含 2 个字符串项的列表。使用 csv.writer() 将其写入 CSV 文件的正确方法是使用 writerow(bac2data).

您代码的最后一部分包含一些错误。首先，您将以写入模式 ('w') 为传入数据的每一行打开 CSV 文件。这将每次覆盖文件，丢失除最后一行以外的所有数据。然后您将遍历 bac2data 列表并在每个项目上调用 writerows()。这会将字符串中的每个字符写在它自己的行上（与您报告的输出相匹配）。

相反，打开输出文件并在主 for info in data: 循环之外创建一个 csv.writer：

fo = open("C:\Users\Siddhartha\Documents\INFS 772\Project\Answer\BAC2_answer.csv", "w")
writer = csv.writer(fo)
for info in data:
    ....

然后替换主循环底部的这些行：

    bac2data = [time_n_date, sentiment]
    print bac2data
    fo = open("C:\Users\Siddhartha\Documents\INFS 772\Project\Answer\BAC2_answer.csv", "w")
    for x in bac2data:
        w = csv.writer(fo, delimiter = ',')
        w.writerows(x)
    fo.close()

有了这个：

    bac2data = [time_n_date, sentiment]
    print bac2data
    writer.writerow(bac2data)

一旦你开始工作，并且不再需要打印 bac2data 进行调试，你可以只使用 1 行：

    writer.writerow((time_n_date, sentiment)]

更新

函数的完整代码：

def sentiment_analysis():
    fo = open("positive_words.txt", "r")
    positive_words = fo.readlines()
    fo.close()
    positive_words = map(lambda positive_words: positive_words.strip(), positive_words)
    fo = open("negative_words.txt", "r")
    negative_words = fo.readlines()
    fo.close()
    negative_words = map(lambda negative_words: negative_words.strip(), negative_words)
    fo = open("BAC.csv", "r")
    data = fo.readlines()
    fo.close()
    data = map(lambda data: data.strip(), data)
    x1 = 0 #number of bullish
    x2 = 0 #number of bearish
    x3 = 0 #number of unknown

    fo = open("C:\Users\Siddhartha\Documents\INFS 772\Project\Answer\BAC2_answer.csv", "w")
    writer = csv.writer(fo)

    for info in data:
        data_specs = info.split(',')
        time_n_date = data_specs[0]
        sentiment = data_specs[2]
        '''Possibly precede with a nested for loop for data_specs???'''
        if sentiment == 'Bullish':
            '''fo.write(time + ',' + 'Bullish' + '\n')'''
        elif sentiment == 'Bearish':
            ''' fo.write(time + ',' + 'Bearish' + '\n')'''
        else:
            x3 += 1
            positive = 0
            negative = 0
            content_words = data_specs[1].split()
            for a in positive_words:
                for b in content_words:
                    if (a == b):
                        positive = positive + 1
            for c in negative_words:
                for d in content_words:
                    if (c == d):
                        negative = negative + 1
            if positive > negative:
                '''fo.write(time + ',' + 'Bullish' + '\n')'''
                sentiment = 'Bullish'
            elif positive < negative:
                sentiment = 'Bearish'
            else:
                sentiment = 'Neutral'

        bac2data = [time_n_date, sentiment]
        print bac2data
        writer.writerow(bac2data)

    fo.close()

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