Python CSV joining columns <p>I am trying to make a new columnn with conditional statements utilizing Pandas Version 0.17.1. I have two csv's both about 100mb's in size.<br> What I have:</p> <p>CSV1:</p> <pre><code> Index TC_NUM 1241 1105.0017 1242 1105.0018 1243 1105.0019 1244 1105.002 1245 1105.0021 1246 1105.0022 </code></pre> <p>CSV2:</p> <pre><code>KEYS TC_NUM UXS-689 3001.0045 FIT-3015 1135.0027 FIT-2994 1140.0156 FIT-2991 1910, 1942.0001, 3004.0004, 3004.0020, 3004.0026, 3004.0063, 3004.0065, 3004.0079, 3004.0084, 3004.0091, 2101.0015, 2101.0016, 2101.0017, 2101.0018, 2101.0050, 2101.0052, 2101.0054, 2101.0055, 2101.0071, 2101.0074, 2101.0075, 2206.0001, 2103.0001, 2103.0002, 2103.0009, 2103.0011, 3000.0004, 3000.0030, 1927.0020 FIT-2990 2034.0002, 3004.0035, 3004.0084, 2034.0001 FIT-2918 3001.0039, 3004.0042 </code></pre> <p>What I want:</p> <pre><code> Index TC_NUM Matched_Keys 1241 1105.0017 FIT-3015 1242 1105.0018 UXS-668 1243 1105.0019 FIT-087 1244 1105.002 FIT-715 1245 1105.0021 FIT-910 1246 1105.0022 FIT-219 </code></pre> <p>If the TC_NUM in CSV2 matches the TC_NUM from CSV1, it prints the key in a column on CSV1</p> <p>Code:</p> <pre><code>dftakecolumns = pd.read_csv('JiraKeysEnv.csv') dfmergehere = pd.read_csv('output2.csv') s = dftakecolumns['KEYS'] a = dftakecolumns['TC_NUM'] d = dfmergehere['TC_NUM'] for crows in a: for toes in d: if toes == crows: print toes dfmergehere['Matched_Keys'] = dftakecolumns.apply(toes, axis=None, join_axis=None, join='outer') </code></pre>