xtensor is a C++ library meant for numerical analysis with multi-dimensional array expressions.

xtensor provides

an extensible expression system enabling lazy broadcasting.
an API following the idioms of the C++ standard library.
tools to manipulate array expressions and build upon xtensor.

Containers of xtensor are inspired by NumPy, the Python array programming library. Adaptors for existing data structures to be plugged into our expression system can easily be written.

In fact, xtensor can be used to process NumPy data structures inplace using Python's buffer protocol. Similarly, we can operate on Julia and R arrays. For more details on the NumPy, Julia and R bindings, check out the xtensor-python, xtensor-julia and xtensor-r projects respectively.