How to Filter Strings in a List Based on Substrings?

Filtering Strings in a List Based on Substrings

Given a list of strings, how can we filter it to include only those that contain a specific substring? For instance, if we have the list ['a', 'ab', 'abc', 'bac'], we would want to obtain the list ['ab', 'abc'].

Solution Using List Comprehension

One efficient method involves using Python's list comprehensions:

<code class="python">lst = ['a', 'ab', 'abc', 'bac']
result = [k for k in lst if 'ab' in k]</code>

The list comprehension iterates over each string k in lst and checks if the substring 'ab' exists within it. If true, k is added to the result list.

Alternative Approach Using Filter

Alternatively, we can employ the filter function to achieve the same result:

<code class="python">lst = ['a', 'ab', 'abc', 'bac']
result = list(filter(lambda k: 'ab' in k, lst))</code>

Here, the filter function takes a lambda function that checks for the presence of 'ab' in each string. The resulting iterator is then converted into a list using list.

Conclusion

Both list comprehensions and the filter function offer effective means to filter a list of strings based on specific content. The choice between the two methods depends on personal preference and code readability.

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