Compare element by element two arrays for close or identical values


is there any function in ROOT to compare element by element two different arrays and check that their values are close enough (within a certain epsilon) or identical?
For example numpy has isclose and allclose that will check if element-wise the values are similar and will return a corresponding array of booleans or a single boolean (true if all values close).

I found nothing in TArrayD or in TVector, and I do not think TH1D has such feature.
Any other class I could use?
I am writing some automatic tests and I want to check the values in a histogram that I produce during the test against a reference histogram I have saved.

Thanks a lot,


Hi @cosimoNigro,
I don’t think ROOT has such an helper function (@moneta can confirm/deny), but if you are writing tests you can define it in 3 lines, e.g. with gtest:

void allclose(const std::vector<double> &v1, const std::vector<double> &v2) {
   const auto s = v1.size();
   ASSERT_EQ(s, v2.size());
   for (auto i = 0u; i < s; ++i)
      EXPECT_NEAR(v1[i], v2[i]);

We would also be glad to accept an IsClose or AllClose implementation for RVec if you ended up implementing one anyway and felt like contributing it upstream.


Look at TMath::AreEqualAbs(x1,x2,eps) and TMath::AreEqualRel(x1,x2,eps)


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