sheet.py

A tiny spreadsheet in Python.

Names

• Column names are a sequence of uppercase and/or lowercase characters. eg: 'a', 'AB', 'foo'. Hint: Columns are not ordered. 'A' does not necessarily come before 'B'.
• Row names are a sequence of digits. eg: 12,0, 1.
• Cells are named by their column and row names written together. eg: 'foo12', 'A1'

Values

A cell can hold any valid Python object as its value. Formulas can be specified by callables. For eg:

lambda a1: a1+1           # The cell's value is one greater than the value in the cell named 'a1'
lambda a2, b2: a2-b2      # Dependency on 2 cells: 'a2' and 'b2'
lambda marks: sum(marks)  # Dependency on the entire column named 'marks'
lambda _1 : len(_1)       # Dependency on row '1'

Operations

There are only 3:

1. create_sheet() which returns a new sheet object.
2. put(sheet, name, value) which enters the value value into the cell named name.
3. get(sheet, name) which returns the value at the cell named name.

Sample Session

# Irrelevant output edited out

>>> from sheet import *
>>> sheet1 = create_sheet()
>>> i = 0
>>> for subject, mark in [('Transfiguration', 70), ('Charms', 72), ('Portions', 74)]:
...   put(sheet1, 'subjects'+str(i), subject)
...   put(sheet1, 'marks'+str(i), mark)
...   i = i + 1
>>> put(sheet1, 'total0', lambda marks: sum(marks))
216
>>> put(sheet1, 'avg0', lambda total0, subjects: total0/len(subjects))
72.0
>>> put(sheet1, 'subjects3', 'Defence Against the Dark Arts')
>>> put(sheet1, 'marks3', 75)
>>> get(sheet1, 'total0')
291
>>> get(sheet1, 'avg0')
72.75