CODEWITHSUNDEEP
pythonpandasdataframe
nappingkid
nappingkid

Reputation: 175

Switch boolean output to string in pandas python

When comparing two dataframes and putting the result back into a dataframe:

dfA = pd.DataFrame({'Column':[1,2,3,4]})

or in human readable form:

    Column
0   1
1   2
2   3
3   4

dfB = pd.DataFrame({'Column':[1,2,4,3]})

or in human readable form:

    Column
0   1
1   2
2   4
3   3

pd.DataFrame(dfA > dfB)

pandas outputs a dataframe with true or false values. 

    Column
0   False
1   False
2   False
3   True

Is it possible to change the name from 'true' or 'false' to 'lower' or 'higher'? I want to know if the outcome is higher, lower or equal, that is why I ask. If the output is not higher or lower, (true or false) then it must be equal.

Upvotes: 1

Views: 202

Answers (2)

cs95
cs95

Reputation: 402303

I'd recommend np.where for performance/simplicity.

pd.DataFrame(np.where(dfA > dfB, 'higher', 'lower'), columns=['col'])

      col
0   lower
1   lower
2   lower
3  higher

You can also nest conditions if needed with np.where, 

m1 = dfA > dfB
m2 = dfA < dfB  
pd.DataFrame(
    np.where(m1, 'higher', np.where(m2, 'lower', 'equal')),
    columns=['col']
)

Or, follow a slightly different approach with np.select.

pd.DataFrame(
    np.select([m1, m2], ['higher', 'lower'], default='equal'),
    columns=['col']
)


      col
0   equal
1   equal
2   lower
3  higher

Upvotes: 1

user3483203
user3483203

Reputation: 51165

You may use map:

In [10]: pd.DataFrame(dfA > dfB)['Column'].map({True: 'higher', False: 'lower'})
Out[10]:
0     lower
1     lower
2     lower
3    higher
Name: Column, dtype: object

Upvotes: 2

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