Addin03.md

Something a bit more interesting - NumPy arrays

One of the attractions of using Python from Excel is to gain access to the vast range of publicly available Python libraries for numerical computing. Since NumPy is the cornerstone of many of these libraries, the ExcelPython add-in makes it easy to pass function arguments as and convert return values from numpy arrays.

We will now define a simple function for doing matrix multiplication using NumPy.

• Add the following code to Book1.py from the first tutorial

  @xlfunc
  @xlarg("x", "nparray", dims=2)
  @xlarg("y", "nparray", dims=2)
  def MatrixMult(x, y):
      return x.dot(y)

• Click 'Import Python UDFs' to pick up the changes

• The function MatrixMult can now be used as an array function from Excel

  

  To enter the above array formula in Excel

  • fill in the values in the ranges D1:E2 and G1:H2
  • select cells A1:B2
  • type in the formula =MatrixMult(D1:E2, G1:H2)
  • press Ctrl+Shift+Enter.

To continue move onto the next tutorial.