找到文件之间的通用列表

时间:2013-03-29 20:17:52

标签: python compare venn-diagram

我有三个文本文件:

fileA:

13  abc
123 def
234 ghi
1234    jkl
12  mno

FILEB:

12  abc
12  def
34  qwe
43  rty
45  mno

fileC:

12  abc
34  sdg
43  yui
54  poi
54  def

我想看看第二列中的所有值在文件之间是否匹配。如果第二列已经排序,则以下代码有效。但如果第二列没有排序,我如何排序第二列并比较文件?

fileA = open("A.txt",'r')
fileB = open("B.txt",'r')
fileC = open("C.txt",'r')

listA1 = []
for line1 in fileA:
    listA = line1.split('\t')
    listA1.append(listA)


listB1 = []
for line1 in fileB:
    listB = line1.split('\t')
    listB1.append(listB)


listC1 = []
for line1 in fileC:
    listC = line1.split('\t')
    listC1.append(listC)

for key1 in listA1:
    for key2 in listB1:
        for key3 in listC1:
            if key1[1] == key2[1] and key2[1] == key3[1] and key3[1] == key1[1]:
                print "Common between three files:",key1[1]

print "Common between file1 and file2 files:"
for key1 in listA1:
    for key2 in listB1:
        if key1[1] == key2[1]:
            print key1[1]

print "Common between file1 and file3 files:"
for key1 in listA1:
    for key2 in listC1:
        if key1[1] == key2[1]:
            print key1[1]

1 个答案:

答案 0 :(得分:3)

如果您只想在第二列排序A1B1C1,这很容易:

listA1.sort(key=operator.itemgetter(1))

如果您不理解itemgetter,则相同:

listA1.sort(key=lambda element: element[1])

但是,我认为更好的解决方案是使用set

setA1 = set(element[1] for element in listA1)
setB1 = set(element[1] for element in listB1)
setC1 = set(element[1] for element in listC1)

或者更简单地说,不要首先建立列表;这样做:

setA1 = set()
for line1 in fileA:
    listA = line1.split('\t')
    setA1.add(listA[1])

无论哪种方式:

print "Common between file1 and file2 files:"
for key in setA1 & setA2:
    print key

为了进一步简化,您可能希望首先将重复的内容重构为函数:

def read_file(path):
    with open(path) as f:
        result = set()
        for line in f:
            columns = line.split('\t')
            result.add(columns[1])
    return result

setA1 = read_file('A.txt')
setB1 = read_file('B.txt')
setC1 = read_file('C.txt')

然后你可以找到更多的机会。例如:

def read_file(path):
    with open(path) as f:
        return set(row[1] for row in csv.reader(f))

正如John Clements所指出的那样,你甚至不需要将它们全部三个都设置为A1,所以你可以这样做:

def read_file(path):
    with open(path) as f:
        for row in csv.reader(f):
            yield row[1]

setA1 = set(read_file('A.txt'))
iterB1 = read_file('B.txt')
iterC1 = read_file('B.txt')

您需要的唯一其他更改是,您必须致电intersection而不是使用&运算符,因此:

for key in setA1.intersection(iterB1):

我不确定这最后的改变实际上是一种改进。但是在Python 3.3中,您唯一需要做的就是将return set(…)更改为yield from (…),我可能会 这样做。 (即使文件很庞大并且有大量的重复项,因此它的性能成本也很高,我只会在unique_everseen调用的itertools个方法中添加read_file。)