python - python中的变量赋值错误

Question

我收到一个变量分配错误，显然我不理解某些东西，但从我的代码中我看不出它为什么会发生。

编码：

   def something(filename):
    with open("tmp/"+filename.stem+".txt", "r") as infile: # opening the tmp file for scraping the data
        readfile = infile.readlines() #reads the infile lne by line and returns a list containing the lines
        for i, line in enumerate(readfile[1:], 1): # looping over all the lines in the file from position 1 (so skipping 0) to avoid circular feedback
            if 'Overview' in line:
                start = i
                continue
                for i, line in enumerate(readfile[1:], 1):
                    if 'Identified secondary metabolite regions using strictness' in line:
                        end = i
                        marker = list(map(lambda s: s.strip('\n'), readfile[start + 1:end])) # stripping the '\n' off every element in the list. map executes a function for each element in a sequence
        for i, line in enumerate(readfile[1:], 1): # looping over all the lines in the file from position 1 (so skipping 0) to avoid circular feedback
            for location in marker:

错误：

UnboundLocalError: local variable 'marker' referenced before assignment

marker由于第一个forloop在第二个forloop之前执行导致marker被设置，不应该总是在函数范围内分配吗？

其次，使用两个 for 循环似乎很麻烦，我怎样才能在一个 for 循环中做到这一点？

标签： pythonpython-3.x

Answer 1

关键是marker在“如果”条件下分配。如果是假的怎么办？