Iterate through columns in Read-only workbook in openpyxl

If the worksheet has only around 100,000 cells then you shouldn't have any memory problems. You should probably investigate this further.

iter_cols() is not available in read-only mode because it requires constant and very inefficient reparsing of the underlying XML file. It is however, relatively easy to convert rows into columns from iter_rows() using zip.

def _iter_cols(self, min_col=None, max_col=None, min_row=None,
               max_row=None, values_only=False):
    yield from zip(*self.iter_rows(
        min_row=min_row, max_row=max_row,
        min_col=min_col, max_col=max_col, values_only=values_only))

import types
for sheet in workbook:
    sheet.iter_cols = types.MethodType(_iter_cols, sheet)

According to the documentation, ReadOnly mode only supports row-based reads (column reads are not implemented). But that's not hard to solve:

wb2 = Workbook(write_only=True)
ws2 = wb2.create_sheet()

# find what column I need
colcounter = 0
for row in ws.rows:
    for cell in row:
        if cell.value == "PerceivedSound.RESP":
            break
        colcounter += 1
    
    # cells are apparently linked to the parent workbook meta
    # this will retain only values; you'll need custom
    # row constructor if you want to retain more

    row2 = [cell.value for cell in row]
    ws2.append(row2) # preserve the first row in the new file
    break # stop after first row

for row in ws.rows:
    row2 = [cell.value for cell in row]
    row2.append(doStuff(row2[colcounter]))
    ws2.append(row2) # write a new row to the new wb
    
wb2.save('newfile.xlsx')
wb.close()
wb2.close()

# copy `newfile.xlsx` to `generalpath + exppath + doc`
# Either using os.system,subprocess.popen, or shutil.copy2()

You will not be able to write to the same workbook, but as shown above you can open a new workbook (in writeonly mode), write to it, and overwrite the old file using OS copy.

This might be slower solution but given your query was to iterate through a single row tuple- i found a better solution

rowId=1
for i in range(len(ws[str(rowId)])):
    #print(str(ws[dbNameRow][i].value) + ' ' + str(i))
    if ws[dbNameRow][i].value == "<Provide your search string here>":
            lastColumn=i+1 #because counter starts from 0