b = [['50.561872473 25.047160868 0.0'], ['50.561905852 25.047537575 0.0'],
    ['50.561905852 25.047537575 0.0'], ['50.561905852 25.047537575 0.0'], [
    '50.562232967 25.048109789 0.0'], ['50.562232967 25.048109789 0.0'], [
    '50.561940185 25.047914282 1.0'], ['50.561940185 25.047914282 1.0'], [
    '50.561940185 25.047914282 1.0']]
df_a = pd.DataFrame(a)
df_b = pd.DataFrame(b)
print(df_a.merge(df_b))
Join two numpy arrays of unequal size and fill third array based on common column