Python 3：用多个相同的关键字格式化一个字符串，但用唯一的字符串来替换它们

Question

我想知道如何在 Python 3.4 中使用列表来格式化多个相同的关键字。我设置它的方式是用户可以传入一个字符串，该字符串具有多个关键字，程序将在它们的位置生成名称，结果应该是一个句子，关键字替换为名称。

我已经创建了一种方法，可以根据程序在用户传入的字符串中看到的数量来生成名称，但由于字符串的性质，无法立即替换它们。由于该字符串有多个相同的关键字（例如 {name}），我需要能够用一个唯一的字符串替换它们中的每一个。这在 Python 3.4 中可能吗？

用户传入的字符串可以是

"{name} had a wonderful day at the park, but then {name} came and ruined it"

程序生成名称后应该是

"John had a wonderful day at the park, but then Bob came and ruined it"

干杯。

编辑：要补充一点，我没有发现任何关于使用列表或具有多个关键字但唯一替换的内容，所以如果我必须用另一种方式而不是替换它也可以。

Answer 1

您可以将 string.replace 与可选的 count 参数一起使用，并将其限制为每次仅替换一个名称：

>>> names = ['John', 'Bob']
>>> message = "{name} had a wonderful day at the park, but then {name} came and ruined it"
>>> i = 0;
>>> while '{name}' in message:
...     message = message.replace('{name}', names[i], 1)
...     i += 1
... 
>>> message
'John had a wonderful day at the park, but then Bob came and ruined it'

Answer 2

您可以使用count参数：

>>> s = "{name} had a wonderful day at the park, but then {name} came and ruined it"
>>> s = s.replace('{name}', 'John', count=1)
>>> s
'John had a wonderful day at the park, but then {name} came and ruined it'

>>> s = s.replace('{name}', 'Bob', count=1)
>>> s
'John had a wonderful day at the park, but then Bob came and ruined it'

Answer 3

如果我没理解错的话，这应该有效：
first_name = Bob
second_name = Sam
"%s had a wonderful day at the park, but then %s came and ruined it" % (first_name, second_name)

可能是最简洁的方法

Answer 4

如果您已经根据每个替换的出现次数预先生成了一个项目列表，您可以使用 re.sub 以编程方式从列表中选择下一个项目。这将比 str.replace 具有更好的性能，尤其是。如果您有大量关键字词典和大量文本。

例如：

import re

# Function to look up an item and return the next thing in its list.
def replace(m):
    return D[m.group(1)].pop(0)

D = {'name' : ['John','Bob'], 'place' : ['park']}

text = "{name} had a wonderful day at the {place}, but then {name} came and ruined it"
new_text = re.sub('{(.*?)}',replace,text)
print(new_text)

输出：

John had a wonderful day at the park, but then Bob came and ruined it

不过，您似乎想要不同名称的不同变量。然后你可以只使用 format 和字典：

重新导入

D = {'name1':'John', 'name2':'Bob', 'place':'park'}
text = "{name1} had a wonderful day at the {place}, but then {name2} came and ruined it. {name2} is a jerk!"
print(text.format(**D))

输出：

John had a wonderful day at the park, but then Bob came and ruined it. Bob is a jerk!

Answer 5

如果短语总是像示例中那样间隔良好，您可以这样做

s = "{name} had a wonderful day at the park, but then {name} came and ruined it"
names = ['John', 'Bob']
ni = iter(names)
outs = ' '.join(next(ni) if el=='{name}' else el for el in s.split())
print(outs)

产生

'John had a wonderful day at the park, but then Bob came and ruined it'

Python 3：用多个相同的关键字格式化一个字符串，但用唯一的字符串来替换它们

Python 3: Formatting a string with multiple same keywords but unique strings to replace them

python

string

replace

keyword

python-3.x