python merge two pandas data frames based on partial string match

I'm new to Python, and I am having a lot of trouble joining two pandas data frames, because the merge should be based on a partial string match. More specifically: I have a dataframe called `df` that looks like this: `{ "writtenAt":"2015-01-01T18:31:01+00:00", "content":" India\u2019s banks will ramp up sales of bonds that act as capital buffers in 2015" }` where there are about 10,000 rows that looks like above. Now, I have another dataframe called `compNames`, which looks like this: `{ "ticker":"A", "name":"Agilent Technologies Inc.", "keyword":"Agilent" }` I have about 500 rows for the `compNames` dataframe. I am trying to assign a ticker value from `compNames` to the matching entry of `df` by the following mechanism: check if any item from the entire column `compNames['keyword']` is contained in an entry of `df['content']` if there is a match, then return the matching word as a separate column of the `df` dataframe (e.g.`df['matchedName']`) if there are multiple matches, then create a list of matching words to the corresponding entry of `df['content']` Finally, join `df` and `compNames` by using `df['matchedName']` and `compNames['keyword']` as my key variables What I have so far is: ``` # Load select company names compNames = pd.read_csv("compNameList_LARA.txt") compList = '|'.join(compNames['keyword'].tolist()) df['compMatch'] = df.content.str.contains(compList) # drop unmatched articles df = df[df['compMatch']==True] # assign firm names df['matchedName'] = df['content'].apply(lambda x: [x for x in compNames['keyword'].tolist() if x in df['content']]) ``` However, when I do this, I get an empty list for the `df['matchedName']` Could you help me figure out what went wrong? Many many thanks!! -Jin