Match column values of 2 different dataframe but of different length

Question

I have TOTAL 2 dataset where dataset1 has PATIENTID column of around 40 entries and another dataset2 has Same PATIENTID of around 700 entries

I want to check if the PATIENTID of dataset1 are present in dataset2 or not.

I tried in Python Jupyter notebook, it is not working though through Python code.

PatientsNotTreated=unique(Datase1.PatientID)[!unique(Dataset1.PatientID) in unique(Dataset2.PatientID)]
PatientsNotTreated

I am getting error:

PatientsNotTreated=unique(Datase1.PatientID)[!unique(Dataset1.PatientID) in unique(Dataset2.PatientID)]
                                                     ^
    SyntaxError: invalid syntax

I expect output of patientID which are not present in daTASET2

Answer 1

Use Series.isin to make a boolena indexing with DataFrame.loc . Finally use Series.unique :

arr_out=Dataset1.loc[~Dataset1['PatientID'].isin(Dataset2['PatientID']),'PatientID'].unique()

---

arr_in=Dataset1.loc[Dataset1['PatientID'].isin(Dataset2['PatientID']),'PatientID'].unique()

---

to filter dataset1 according to the patient use:

Dataset1_filtered=Dataset1.loc[~Dataset1['PatientID'].isin(Dataset2['PatientID'])]