复数字符串格式 [英] Plural String Formatting

问题描述

给出一个 int s的字典，我正在尝试使用每个数字和一个复数形式格式化字符串.

Given a dictionary of ints, I'm trying to format a string with each number, and a pluralization of the item.

样本输入 dict :

data = {'tree': 1, 'bush': 2, 'flower': 3, 'cactus': 0}

示例输出 str :

'My garden has 1 tree, 2 bushes, 3 flowers, and 0 cacti'

它需要使用任意格式的字符串.

It needs to work with an arbitrary format string.

我想出的最好的解决方案是一个 PluralItem 类，用于存储两个属性 n (原始值)和 s (如果为复数，则为字符串's ，否则为空字符串'').为不同的多元化方法分类

The best solution I've come up with is a PluralItem class to store two attributes, n (the original value), and s (the string 's' if plural, empty string '' if not). Subclassed for different pluralization methods

class PluralItem(object):
    def __init__(self, num):
        self.n = num
        self._get_s()
    def _get_s(self):
        self.s = '' if self.n == 1 else 's'

class PluralES(PluralItem):
    def _get_s(self):
        self.s = 's' if self.n == 1 else 'es'

class PluralI(PluralItem):
    def _get_s(self):
        self.s = 'us' if self.n == 1 else 'i'

然后通过理解和 classes 映射来创建新的 dict :

Then make a new dict through comprehension and a classes mapping:

classes = {'bush': PluralES, 'cactus': PluralI, None: PluralItem}
plural_data = {key: classes.get(key, classes[None])(value) for key, value in data.items()}

最后，格式字符串和实现:

Lastly, the format string, and implementation:

formatter = 'My garden has {tree.n} tree{tree.s}, {bush.n} bush{bush.s}, {flower.n} flower{flower.s}, and {cactus.n} cact{cactus.s}'
print(formatter.format(**plural_data))

输出以下内容:

My garden has 1 tree, 2 bushes, 3 flowers, and 0 cacti

---

对于这种毫无疑问的普遍需求，我很犹豫地将这种复杂的解决方案扔进毛巾里.

---

For such an undoubtedly common need, I'm hesitant to throw in the towel with such a convoluted solution.

是否有一种使用内置的 format 方法格式化字符串的方法，并且只需最少的附加代码?伪代码可能类似于:

Is there a way to format a string like this using the built-in format method, and minimal additional code? Pseudocode might be something like:

"{tree} tree{tree(s)}, {bush} bush{bush(es)}, {flower} flower{flower(s)}, {cactus} cact{cactus(i,us)}".format(data)

如果值是复数，或者如果内容具有逗号，则括号返回内容，表示复数/单数

where parentheses return the contents if value is plural, or if contents has comma, means plural/singular

推荐答案

使用自定义格式程序:

import string

class PluralFormatter(string.Formatter):
    def get_value(self, key, args, kwargs):
        if isinstance(key, int):
            return args[key]
        if key in kwargs:
            return kwargs[key]
        if '(' in key and key.endswith(')'):
            key, rest = key.split('(', 1)
            value = kwargs[key]
            suffix = rest.rstrip(')').split(',')
            if len(suffix) == 1:
                suffix.insert(0, '')
            return suffix[0] if value <= 1 else suffix[1]
        else:
            raise KeyError(key)

data = {'tree': 1, 'bush': 2, 'flower': 3, 'cactus': 0}
formatter = PluralFormatter()
fmt = "{tree} tree{tree(s)}, {bush} bush{bush(es)}, {flower} flower{flower(s)}, {cactus} cact{cactus(i,us)}"
print(formatter.format(fmt, **data))

输出:

1 tree, 2 bushes, 3 flowers, 0 cacti

更新

如果您使用的是Python 3.2+( str.添加了format_map )，您可以使用使用自定义字典的OP的想法(请参见评论).

If you're using Python 3.2+ (str.format_map was added), you can use the idea of OP (see comment) that use customized dict.

class PluralDict(dict):
    def __missing__(self, key):
        if '(' in key and key.endswith(')'):
            key, rest = key.split('(', 1)
            value = super().__getitem__(key)
            suffix = rest.rstrip(')').split(',')
            if len(suffix) == 1:
                suffix.insert(0, '')
            return suffix[0] if value <= 1 else suffix[1]
        raise KeyError(key)

data = PluralDict({'tree': 1, 'bush': 2, 'flower': 3, 'cactus': 0})
fmt = "{tree} tree{tree(s)}, {bush} bush{bush(es)}, {flower} flower{flower(s)}, {cactus} cact{cactus(i,us)}"
print(fmt.format_map(data))

输出:与上面相同.

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