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pythonpandasstring-matchingboolean-expression

Pandas - check if a string column in one dataframe contains a pair of strings from another dataframe


This question is based on another question I asked, where I didn't cover the problem entirely: Pandas - check if a string column contains a pair of strings

This is a modified version of the question.

I have two dataframes :

df1 = pd.DataFrame({'consumption':['squirrel ate apple', 'monkey likes apple', 
                                  'monkey banana gets', 'badger gets banana', 'giraffe eats grass', 'badger apple loves', 'elephant is huge', 'elephant eats banana tree', 'squirrel digs in grass']})

df2 = pd.DataFrame({'food':['apple', 'apple', 'banana', 'banana'], 
                   'creature':['squirrel', 'badger', 'monkey', 'elephant']})

The goal is to test if df.food:df.creature pairs are present in df1.consumptions.

The expected answer for this test in the above example would be :

['True', 'False', 'True', 'False', 'False', 'True', 'False', 'True', 'False']

The pattern is:

squirrel ate apple = True since squirrel and apple is a pair. monkey likes apple = False since monkey and apple is not a pair we are looking for.

I was thinking of constructing a dictionary of dataframes of the pair-values where each dataframe would be for one creature for e.g.squirrel, monkey etc. and then using np.where to create a boolean expression and perform a str.contains.

Not sure if that is the easiest way.


Solution

  • Consider this vectorized approach:

    from sklearn.feature_extraction.text import CountVectorizer
    
    vect = CountVectorizer()
    
    X = vect.fit_transform(df1.consumption)
    Y = vect.transform(df2.creature + ' ' + df2.food)
    
    res = np.ravel(np.any((X.dot(Y.T) > 1).todense(), axis=1))
    

    Result:

    In [67]: res
    Out[67]: array([ True, False,  True, False, False,  True, False,  True, False], dtype=bool)
    

    Explanation:

    In [68]: pd.DataFrame(X.toarray(), columns=vect.get_feature_names())
    Out[68]:
       apple  ate  badger  banana  digs  eats  elephant  gets  giraffe  grass  huge  in  is  likes  loves  monkey  squirrel  tree
    0      1    1       0       0     0     0         0     0        0      0     0   0   0      0      0       0         1     0
    1      1    0       0       0     0     0         0     0        0      0     0   0   0      1      0       1         0     0
    2      0    0       0       1     0     0         0     1        0      0     0   0   0      0      0       1         0     0
    3      0    0       1       1     0     0         0     1        0      0     0   0   0      0      0       0         0     0
    4      0    0       0       0     0     1         0     0        1      1     0   0   0      0      0       0         0     0
    5      1    0       1       0     0     0         0     0        0      0     0   0   0      0      1       0         0     0
    6      0    0       0       0     0     0         1     0        0      0     1   0   1      0      0       0         0     0
    7      0    0       0       1     0     1         1     0        0      0     0   0   0      0      0       0         0     1
    8      0    0       0       0     1     0         0     0        0      1     0   1   0      0      0       0         1     0
    
    In [69]: pd.DataFrame(Y.toarray(), columns=vect.get_feature_names())
    Out[69]:
       apple  ate  badger  banana  digs  eats  elephant  gets  giraffe  grass  huge  in  is  likes  loves  monkey  squirrel  tree
    0      1    0       0       0     0     0         0     0        0      0     0   0   0      0      0       0         1     0
    1      1    0       1       0     0     0         0     0        0      0     0   0   0      0      0       0         0     0
    2      0    0       0       1     0     0         0     0        0      0     0   0   0      0      0       1         0     0
    3      0    0       0       1     0     0         1     0        0      0     0   0   0      0      0       0         0     0
    

    UPDATE:

    In [92]: df1['match'] = np.ravel(np.any((X.dot(Y.T) > 1).todense(), axis=1))
    
    In [93]: df1
    Out[93]:
                     consumption  match
    0         squirrel ate apple   True
    1         monkey likes apple  False
    2         monkey banana gets   True
    3         badger gets banana  False
    4         giraffe eats grass  False
    5         badger apple loves   True
    6           elephant is huge  False
    7  elephant eats banana tree   True
    8     squirrel digs in grass  False
    9        squirrel.eats/apple   True   # <----- NOTE