Question

我想在Python中读取多个文件，以便在它们之间进行一些映射。

我对这些事情很陌生，所以我从别人那里得到了代码。但现在我想编辑它。我无法完全理解python宏。

所以这是代码

def getDataFromFile(infile):
    '''
    Opens a file, processes it by replacing all the \t\t
    with \t'n/a'\t and returns to the user the header of the file,
    and a list of genes.

    '''
    with open(infile, 'r') as f:
        reader = csv.reader(f, delimiter='\t')                              # Open the file with csv.reader so it has a cleaner look to it.
        header = f.readline()                                               # Store header on a variable
        list = [[x if x else 'n/a' for x in line] for line in reader]   # This is done, so we can have 1 universal input. n/a is for non-existent value!
                                                                            # Most databases, don't insert a special character for non-existent
                                                                            # values, they just \t\t it! So be careful with that!
        # With the above approach, we end up with a list of lists 
        # Every column, will have a value and that will be either the one provided by the file
        # or, the "our" special for non-existent attributes, 'NaN'
        header = header.split() # header should be a list of strings.
        return header, geneList

如何修改此行list = [[x if x else 'n/a' for x in line] for line in reader]，以便不仅检查'/t/t'并将其替换为'n/a'，还会查找其他形式的“不存在”，如{ {1}}（在R中使用）。

我知道这是一个 noob 问题，但我在2周前开始使用Python。我还在学习过程中。

Answer 1

只需在listcomp中添加另一个测试：

list = [[x if (x and x not in ["NA","whatever"]) else 'n/a' for x in line] for line in reader]

这可以更清晰，就像倒置逻辑和在清单中整合空字符串一样。

list = [['n/a' if (x in ["", "NA","whatever"]) else x for x in line] for line in reader]

用Python读取文件并随时替换某些字符串

1 个答案: