arrays - Itertools Groupby Questions -

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i struggling understand how itertools.groupby works. have excel spreadsheet has delivery dates in first column followed destination lat in column 2 , destination lon in column 3. earlier able grouping dates same subarrays of larger array holds them. here code it.

with xlrd.open_workbook(file_location) workbook:     sheet = workbook.sheet_by_index(0)      dates = (sheet.cell_value(i,0) in range(sheet.nrows))     day = [list(group) key, group in itertools.groupby(dates)]

now need take step further , group lat 1 array , lon array, group them day. i've tried combining the code listed above something this, not know how incorporate lat , lon variables itertools groupby function.

with xlrd.open_workbook(file_location) workbook:     sheet = workbook.sheet_by_index(0)      in range(sheet.nrows):         lat = (sheet.cell_value(i,2) in range(sheet.nrows))         deliveryx = [list(group) key, group in itertools.groupby(dates)]         lon = (sheet.cell_value(i,3) in range(sheet.nrows))         deliveryy = [list(group) key, group in itertools.groupby(dates)]

groupby takes key argument decide how group values in given list. make iterable of tuples like:

t = ((lat, lon, date), (lat, lon, date), ...)

you can achieve calling itertools.izip(lat, lon, dates). then, chunk list groups comparing third fields, , extract first , second ones, can write

lats = [[i[0] in g] k, g in groupby(t, key=lambda x: x[2])] lats = [[i[1] in g] k, g in groupby(t, key=lambda x: x[2])]

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