Category Archives: NumPy and SciPy

Using Alglib least-squares solvers

Posted on 23/09/2017 by dougaj4

Following the last post on using the Python version of Alglib from Excel, via xlwings, this post looks in more detail at alternatives for fitting a non-linear function to a set of data, using the Levenberg-Marquardt method.  The spreadsheet with … Continue reading →

Posted in AlgLib, Curve fitting, Excel, Link to Python, Maths, Newton, NumPy and SciPy, UDFs, VBA, xlwings | Tagged , , , , , , , , , , | 2 Comments

Evaluating text and calling Python functions from Excel with xlwings

Posted on 23/08/2017 by dougaj4

The Alglib spreadsheet presented here includes functions to evaluate formulas entered as text on the spreadsheet, or to call specified Python functions.  I have now added a user defined function (UDF) that will perform either of these operations (xl_CallFuncD), and added … Continue reading →

Posted in AlgLib, Excel, Link to Python, Maths, Newton, NumPy and SciPy, UDFs, VBA, xlwings | Tagged , , , , , , , , , | 1 Comment

Using Matplotlib from Excel with xlwings – update

Posted on 07/05/2017 by dougaj4

In February 2016 I posted a spreadsheet with examples of linking to the Python Matplotlib library with xlwings.  Since then updates to xlwings required some changes to the python code, specifically plot.show has been replaced with pictures.add. The spreadsheet has … Continue reading →

Posted in Charts, Charts, Excel, Link to Python, Newton, NumPy and SciPy, VBA | Tagged , , , , , , , | Leave a comment

Indexing NumPy arrays with floats …

Posted on 01/04/2017 by dougaj4

… now you can’t. I recently updated to the latest version of NumPy (1.12.1), and today I discovered that some of my spreadsheets using NumPy arrays (via xlwings) were returning errors like: IndexError: only integers, slices (`:`), ellipsis (`…`), numpy.newaxis … Continue reading →

Posted in Arrays, Excel, Link to Python, NumPy and SciPy, UDFs, VBA | Tagged , , , , , | 2 Comments

The meaning of = in Python

Posted on 26/02/2017 by dougaj4

In VBA, if you have an array named a and a variant named b, then the statement “b = a” creates a new array b with the same size and values as a.  If the values of either a or b are subsequently changed, the values of the … Continue reading →

Posted in Arrays, Excel, Link to Python, NumPy and SciPy, UDFs, VBA | Tagged , , , , , , , , , | 4 Comments