pandas: match substring from a column in dataframe with another dataframe column

Question

I have two dataframe like the following but with more rows:

data = {'First':  [['First', 'value'],['second','value'],['third','value','is'],['fourth','value','is']],
'Second': [['adj','noun'],['adj','noun'],['adj','noun','verb'],['adj','noun','verb']]}

df = pd.DataFrame (data, columns = ['First','Second'])

data2 = {'example':  ['First value is important', 'second value is imprtant too','it us goof to know']}

df2 = pd.DataFrame (data2, columns = ['example'])

I wrote a function that checks if the first word in the example column can be found in the First column in the first dataframe, and if true return the string, like the following:

def reader():
    for l in [l for l in df2.example]:
        if df["first"].str.contains(pat=l.split(' ', 1)[0]).any() is True:
           return l

However, i realized that it would not work because the First column in df is a list of strings, so I made the following modification:

def reader():
    for l in [l for l in df2.example]:
        df['first_unlist'] = [','.join(map(str, l)) for l in df.First]
        if df["first_unlist"].str.contains(pat=l.split(' ', 1)[0]).any() is True:
            return l

however, i still get 'None' when i run the function, and I cannot figure out what is wrong here.

Update:

I would like the function to return the first two strings in the example column, 'First value is important', 'second value is imprtant too'

sheep · Accepted Answer · 2021-09-22 11:27:05Z

1

Your function doesn's return False when the first word in the example column can not be found. Here is the revision.

def reader():
    for l in [l for l in df2.example]:
        df['first_unlist'] = [','.join(map(str, l)) for l in df.First]
   
        if df["first_unlist"].str.contains(pat=l.split(' ', 1)[0]).any() is True:
            return l
    return list(df2.example[:2])

reader()

edited Sep 22, 2021 at 11:27

answered Sep 22, 2021 at 11:10

sheep

1514 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

zara kolagar Over a year ago

thank you for the reply. but i do not want to return False, but I would like to get the first and second strings in the example column as the right values.

sheep Over a year ago

Is ['First value is important', 'second value is imprtant too'] the expected ouput?

zara kolagar Over a year ago

yes exactly, i think i should then create a list to save them and return the list instead, am i right?

sheep Over a year ago

You can try my new answer. I have update it.

Collectives™ on Stack Overflow

pandas: match substring from a column in dataframe with another dataframe column

1 Answer 1

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related