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copied!<p>I would stack generator expressions:</p> <pre><code>with open(filename) as f_in: lines = (line.rstrip() for line in f_in) # All lines including the blank ones lines = (line for line in lines if line) # Non-blank lines </code></pre> <p>Now, <code>lines</code> is all of the non-blank lines. This will save you from having to call strip on the line twice. If you want a list of lines, then you can just do:</p> <pre><code>with open(filename) as f_in: lines = (line.rstrip() for line in f_in) lines = list(line for line in lines if line) # Non-blank lines in a list </code></pre> <p>You can also do it in a one-liner (exluding <code>with</code> statement) but it's no more efficient and harder to read:</p> <pre><code>with open(filename) as f_in: lines = list(line for line in (l.strip() for l in f_in) if line) </code></pre> <h2>Update:</h2> <p>I agree that this is ugly because of the repetition of tokens. You could just write a generator if you prefer:</p> <pre><code>def nonblank_lines(f): for l in f: line = l.rstrip() if line: yield line </code></pre> <p>Then call it like:</p> <pre><code>with open(filename) as f_in: for line in nonblank_lines(f_in): # Stuff </code></pre> <h2>update 2:</h2> <pre><code>with open(filename) as f_in: lines = filter(None, (line.rstrip() for line in f_in)) </code></pre> <p>and on CPython (with deterministic reference counting)</p> <pre><code>lines = filter(None, (line.rstrip() for line in open(filename))) </code></pre> <p>In Python 2 use <code>itertools.ifilter</code> if you want a generator and in Python 3, just pass the whole thing to <code>list</code> if you want a list.</p>

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