在Python中扩展列表中的变量

Question

需要知道如何在列表元素中展开变量

  >>> one_more = "four"
  >>> var_names = ["one", "two", "three_<expand variable one_more>"]

应该得到类似这样的结果

  ['one', 'two', 'three_four']

Answer 1

我猜你是想在一个列表里替换字符串。这里有一个例子可以满足你的需求。

one_more = "four"
var_names = ["one", "two", "three_<var>"]

print [x.replace("<var>", one_more) for x in var_names]

>>> ["one", "two", "three_four"]

如果你想一次性替换多个模式，可以这样做：

a = "AA"
b = "BB"
var_names = ["one", "two", "three_$a", "four_$b"]

def batch_replace(str, lookup):
   for pattern in lookup:
      replacement = lookup[pattern]
      str = str.replace(pattern, replacement)
   return str

print [batch_replace(x, {"$a": a, "$b": b}) for x in var_names] 

>>> ["one", "two", "three_AA", "four_BB"]

Answer 2

非常基础：

In [1]: a="four"    
In [2]: b="five"
In [3]: ['one', 'two', 'three_%s' % a]
Out[3]: ['one', 'two', 'three_four']

你还可以把一组变量连接起来：

In [5]: ['one', 'two', 'three_%s' % '_'.join((a,b))]
Out[5]: ['one', 'two', 'three_four_five']

这里是用 str.format 的同样解决方案：

In [6]: ['one', 'two', 'three_{}'.format('_'.join((a,b)))]
Out[6]: ['one', 'two', 'three_four_five']