Question

我是Python的新手，但我想对一些csv文件进行一些数据分析。我想从仅包含一些关键字的csv文件中打印行。我使用第一个块来打印所有有效行。从这些行我想打印包括关键字的那些。谢谢你的帮助。

csv.field_size_limit(sys.maxsize)
invalids = 0
valids = 0
for f in ['1.csv']:
    reader = csv.reader(open(f, 'rU'), delimiter='|', quotechar='\\')
    for row in reader:
        try:
            print row[2] 
            valids += 1
        except:
            invalids += 1
print 'parsed %s records. ignored %s' % (valids, invalids)

使用关键字：

    for w in ['ford', 'hyundai','honda', 'jeep', 'maserati','audi','jaguar', 'volkswagen','chevrolet','chrysler']:

我想我需要使用if语句来过滤我的顶级代码，但我一直在努力解决这个问题几个小时似乎无法让它发挥作用。

Answer 1

你的猜测是正确的。您需要做的就是使用if语句过滤行，检查每个字段是否与关键字匹配。以下是您的操作方法（我还对您的代码进行了一些改进，并在评论中对其进行了解释。）：

# First, create a set of the keywords. Sets are faster than a list for
# checking if they contain an element. The curly brackets create a set.
keywords = {'ford', 'hyundai','honda', 'jeep', 'maserati','audi','jaguar',
            'volkswagen','chevrolet','chrysler'}
csv.field_size_limit(sys.maxsize)
invalids = 0
valids = 0
for filename in ['1.csv']:
    # The with statement in Python makes sure that your file is properly closed
    # (automatically) when an error occurs. This is a common idiom.
    # In addition, CSV files should be opened only in 'rb' mode.
    with open(filename, 'rb') as f:
        reader = csv.reader(f, delimiter='|', quotechar='\\')
        for row in reader:
            try:
                print row[2] 
                valids += 1
            # Don't use bare except clauses. It will catch
            # exceptions you don't want or intend to catch.
            except IndexError:
                invalids += 1
            # The filtering is done here.
            for field in row:
                if field in keywords:
                    print row
                    break
# Prefer the str.format() method over the old style string formatting.
print 'parsed {0} records. ignored {1}'.format(valids, invalids)

打印包含指定关键字的csv文件行

1 个答案: