How to paste a Numpy array to Excel

My best solution here would be to turn the array into a string, then use win32clipboard to sent it to the clipboard. This is not a cross-platform solution, but then again, Excel is not avalable on every platform anyway.

Excel uses tabs (\t) to mark column change, and \r\n to indicate a line change.

The relevant code would be:

import win32clipboard as clipboard

def toClipboardForExcel(array):
    """
    Copies an array into a string format acceptable by Excel.
    Columns separated by \t, rows separated by \n
    """
    # Create string from array
    line_strings = []
    for line in array:
        line_strings.append("\t".join(line.astype(str)).replace("\n",""))
    array_string = "\r\n".join(line_strings)

    # Put string into clipboard (open, clear, set, close)
    clipboard.OpenClipboard()
    clipboard.EmptyClipboard()
    clipboard.SetClipboardText(array_string)
    clipboard.CloseClipboard()

I have tested this code with random arrays of shape (1000,10000) and the biggest bottleneck seems to be passing the data to the function. (When I add a print statement at the beginning of the function, I still have to wait a bit before it prints anything.)

EDIT: The previous paragraph related my experience in Python Tools for Visual Studio. In this environment, it seens like the print statement is delayed. In direct command line interface, the bottleneck is in the loop, like expected.

As of today, you can also use xlwings. It's open source, and fully compatible with Numpy arrays and Pandas DataFrames.