字符串格式 [str.format()] 带有一个字典键，它是一个数字的 str() [英] String formatting [str.format()] with a dictionary key which is a str() of a number

问题描述

这里是 Python 新手.我想知道是否有人可以帮助我在 str.format.

Python neophyte here. I was wondering if someone could help with the KeyError I am getting when using a dictionary for string interpolation in str.format.

dictionary = {'key1': 'val1', '1': 'val2'}

string1 = 'Interpolating {0[key1]}'.format(dictionary)
print string1

以上工作正常并产生:

Interpolating val1

但是执行以下操作:

dictionary = {'key1': 'val1', '1': 'val2'}

string2 = 'Interpolating {0[1]}'.format(dictionary)
print string2

结果:

Traceback (most recent call last):
  File "test.py", line 3, in <module>
    string2 = 'Interpolating {0[1]}'.format(dictionary)
KeyError: 1L

所以问题似乎在于将数字键解释为列表索引，恕我直言. 有没有办法解决这个问题?(即表示这是一个字典键)

So the problem seems to be in the interpretation of the numeric key as a list index, IMHO. Is there any way to work around this? (i.e. convey that this is instead a dictionary key)

TIA，如果之前有人问过这个问题，我深表歉意(找不到与我的搜索相关的任何内容).

TIA and apologies if this question has been asked before(couldn't find anything relevant with my search-fu).

编辑 1:键不是数字，正如之前错误地指出的那样.相反，它是一个数字的字符串表示 - 正如 BrenBarn 所指出的那样.

Edit 1: The key is not numeric as was erroneously noted, earlier. Instead it is a string representation of a number - as was pointed out by BrenBarn.

推荐答案

没有.根据文档:

因为 arg_name 不是引号分隔的，所以不能在格式字符串中指定任意的字典键(例如，字符串 '10' 或 ':-]').

Because arg_name is not quote-delimited, it is not possible to specify arbitrary dictionary keys (e.g., the strings '10' or ':-]') within a format string.

因此您不能使用由数字组成的字符串作为格式字符串中的字典键.

So you can't use strings consisting of numbers as dictionary keys in format strings.

请注意，您的键不是数字，并且不会尝试将其用作列表索引.您的密钥是一个恰好包含数字字符的字符串.它试图做的是使用数字 1(而不是字符串1")作为字典键.如果您使用数字 1 作为您的字典键(即，使您的 dict {'key1': 'val1', 1: 'val2'})，它将起作用.

Note that your key isn't numeric, and it's not trying to use it as a list index. Your key is a string that happens to contain a digit character. What it's trying to do is use the number 1 (not the string "1") as a dictionary key. It will work if you use the number 1 as your dictionary key (i.e., make your dict {'key1': 'val1', 1: 'val2'}).

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