 <p>I think you need:</p> <pre><code>print (data[0].min(axis=1)) 0 3662.1 1 3660.0 2 3659.5 3 3660.0 4 3661.5 5 3662.6 6 3661.5 7 3660.0 8 3661.5 9 3662.1 10 3660.0 11 3661.0 12 3664.1 13 3664.1 14 3661.5 15 3661.0 ... ... </code></pre> <p>Maybe beter is omit <code>flow = pd.DataFrame(data)</code> and use:</p> <pre><code>data = [pd.read_csv(f, index_col=None, header=None) for f in temp] mins = [df.min(axis=1) for df in data[0]] print (mins[0]) print (mins[1]) </code></pre>