Question

Hi I have an excel file with a similar structure as below:

      Location       column2    column3
1     South Africa
2     
3     
4     
5     England
6     
7     
8     
9     U.S
10    
11    
12    

I am trying to write a python script that can fill out the spaces between each location with the name of the preceding location (i.e fill out the space from 2 to 4 with the South Africa as the location, 6-8 will be filled out with England as the location, etc)

I would be grateful if someone could point me in the right direction.Thanks

Answer 1

Ok dude, I think the answer is this dumb wrapper I made for xlrd (or, one you write yourself!). The key is that the function reads one row at a time into a list, and that Python lists remember the order in which they were populated. The wrapper produces a dictionary which maps Excel sheet names to a list of rows on that sheet (we’re assuming one table per sheet here, you’ll have to generalize things otherwise). Each row is a dictionary whose keys are the column names.

For you, I’d read in your data, and then do something like this (not tested):

import see_below as sb
dict = sb.workbookToDict(your_file)
output = []
this_location = None
for row in dict[relevant_sheet_name]:
    output_row = row
    if row['Location'] is not None:
        this_location = row['Location']
    else:
        output_row['Location'] = this_location

There might be something cute you can do with list comprehension, but I’ve had too much wine to fool with that tonight 🙂

Here’s the wrapper for the reader:

import xlrd


def _isEmpty(_):
        return ''


def _isString(element):
        return element.value.encode('ascii', 'ignore')


def _isFloat(element):
    return float(element.value)


def _isDate(element):
    import datetime
    rawDate = float(element.value)
    return (datetime.datetime(1899, 12, 30) +
            datetime.timedelta(days=rawDate))


def _isBool(element):
    return element.value == 1


def _isExcelGarbage(element):
    return int(element.value)


_options = {0: _isEmpty,
            1: _isString,
            2: _isFloat,
            3: _isDate,
            4: _isBool,
            5: _isExcelGarbage,
            6: _isEmpty}


def WorkbookToDict(filename):
    '''
        Reads .xlsx file into dictionary.

        The keys of the dictionary correspond to sheet names in the Excel workbook.
        The first row of the Excel workbook is taken to be column names, and each row
        of the worksheet is read into a separate dictionary, whose keys correspond to
        column names. The collection of dictionaries (as a list) forms the value in the
        dictionary. The output maps sheet names (keys) to a collection of dictionaries
        (value).
    '''
    book = xlrd.open_workbook(filename)
    allSheets = {}
    for s in book.sheets():
        thisSheet = []
        headings = [_options[x.ctype](x) for x in s.row(0)]

        for i in range(s.nrows):
            if i == 0:
                continue

            thisRow = s.row(i)
            if len(thisRow) != len(headings):
                raise Exception("Mismatch between headings and row length in ExcelReader")

            rowDict = {}
            for h, r in zip(headings, thisRow):
                rowDict[h] = _options[r.ctype](r)
            thisSheet.append(rowDict)
        allSheets[str(s.name)] = thisSheet
    return allSheets

The writer is here:

import xlwt

def write(workbookDict, colMap, filename):
    '''
       workbookDict should be a map of sheet names to a list of dictionaries.
       Each member of the list should be a mapping of column names to contents,
       missing keys are handled with the nullEntry field. colMap should be a
       dictionary whose keys are identical tto the sheet names in the workbookDict.
       Each value is a list of column names that are assumed to be in order.
       If a key exists in the workbookDict that does not exist in the colDict, the
       entry in workbookDict will not be written.
    '''

    workbook = xlwt.Workbook()

    for sheet in workbookDict.keys():
        worksheet = workbook.add_sheet(sheet)
        cols = colMap[sheet]
        i = 0
        writeCols = True
        while i <= len(workbookDict[sheet]):
            if writeCols:
                for j in range(len(cols)):
                    if writeCols:  # write col headings
                        worksheet.write(i, j, cols[j])
                writeCols = False
            else:
                for j in range(len(cols)):
                    worksheet.write(i, j, workbookDict[sheet][(i-1)][cols[j]])
            i += 1

    workbook.save(filename)

Anyway, I really hope this works for you!