打印包含指定关键词的csv文件行

Question

我刚开始学习Python，但我想对一些csv文件进行数据分析。我想打印出csv文件中只包含某些关键词的行。我用第一个代码块打印了所有有效的行。接下来，我想从这些行中打印出包含关键词的那些。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)

包含关键词的：

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

我想我需要用一个if语句来过滤我之前的代码，但我已经为这个问题挣扎了好几个小时，还是没能搞定。

Answer 1

你的猜测是对的。你只需要用一个if语句来筛选出符合条件的行，检查每个字段是否和关键词匹配。下面是你该怎么做的（我还对你的代码做了一些改进，并在注释中解释了这些改进）：

# 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)