python - 向字典添加键和值

Question

我正在尝试向(空)字典中添加一个新的键/值对。我有一个包含字符串(年)的文本文件，脚本应该计算年份的出现次数。

    with open ("results/results_%s.txt" % bla, "r") as myfile:
       for line in myfile:
        line = line.translate(None, ''.join(chars_to_remove))
        abc = line.split("_", 2)
        year = abc[1:2]
        year = ''.join(year)
        year = year.translate(None, ''.join(chars_to_remove))
        raey = {}
        #increment the value of the "year"-key, if not present set it to 0 to avoid key erros
        raey[year] = raey.get(year, 0) + 1

但是，如果这返回例如 {'2004': 1}，但它应该已经构建了一个字典(如 {1993 : 2, 2012 : 3})，如果我在 for 循环中插入一个“打印”语句我得到例如:

{'1985': 1}
{'2062': 1}
{'1993': 1}
{'2000': 1}
{'2007': 1}
{'2009': 1}
{'1993': 1}
{'1998': 1}
{'1993': 1}
{'1998': 1}
{'2000': 1}
{'2013': 1}
{'1935': 1}
{'1999': 1}
{'1998': 1}
{'1992': 1}
{'1999': 1}
{'1818': 1}
{'2059': 1}
{'1990': 1}

它没有构建正确的字典，代码正在用每个循环替换字典。我做错了什么？

Answer 1

问题是您在 for 循环中初始化 dict，因此每次都会创建一个新的。相反，将其移出

with open ("results/results_%s.txt" % bla, "r") as myfile:
  raey = {}
  for line in myfile:
    line = line.translate(None, ''.join(chars_to_remove))
    abc = line.split("_", 2)
    year = abc[1:2]
    year = ''.join(year)
    year = year.translate(None, ''.join(chars_to_remove))
    #increment the value of the "year"-key, if not present set it to 0 to avoid key erros
    raey[year] = raey.get(year, 0) + 1