# Working with Data Structures¶

## Single Cells¶

Single cells are returned either as float, unicode, None or datetime objects, depending on whether the cell contains a number, a string, is empty or represents a date:

>>> from xlwings import Workbook, Range
>>> from datetime import datetime
>>> wb = Workbook()
>>> Range('A1').value = 1
>>> Range('A1').value
1.0
>>> Range('A2').value = 'Hello'
>>> Range('A2').value
'Hello'
>>> Range('A3').value is None
True
>>> Range('A4').value = datetime(2000, 1, 1)
>>> Range('A4').value
datetime.datetime(2000, 1, 1, 0, 0)


## Lists¶

• 1d lists: Ranges that represent rows or columns in Excel are returned as simple lists:

>>> wb = Workbook()
>>> Range('A1').value = [[1],[2],[3],[4],[5]]  # Column orientation (nested list)
>>> Range('A1:A5').value
[1.0, 2.0, 3.0, 4.0, 5.0]
>>> Range('A1').value = [1, 2, 3, 4, 5]
>>> Range('A1:E1').value
[1.0, 2.0, 3.0, 4.0, 5.0]

• 2d lists: If the row or column orientation has to be preserved, use the atleast_2d keyword. This will return the Ranges as nested lists (“2d lists”):

>>> Range('A1:A5', atleast_2d=True).value
[[1.0], [2.0], [3.0], [4.0], [5.0]]
>>> Range('A1:E1', atleast_2d=True).value
[[1.0, 2.0, 3.0, 4.0, 5.0]]

• 2 dimensional Ranges are automatically returned as nested lists. When assigning (nested) lists to a Range in Excel, it’s enough to just specify the top left cell as target address. This sample also makes use of index notation to read the values back into Python:

>>> Range('A10').value = [['Foo 1', 'Foo 2', 'Foo 3'], [10, 20, 30]]
>>> Range((10,1),(11,3)).value
[['Foo 1', 'Foo 2', 'Foo 3'], [10.0, 20.0, 30.0]]


Note

Try to minimize the number of interactions with Excel. It is always more efficient to do Range('A1').value = [[1,2],[3,4]] than Range('A1').value = [1, 2] and Range('A2').value = [3, 4].

## The “table”, “vertical” and “horizontal” properties¶

Continuing the sample from above, you can get the dimensions of Excel Ranges dynamically through the properties table, vertical and horizontal. All that’s needed is the top left cell together with one of these properties.

>>> Range('A10').table.value
[['Foo 1', 'Foo 2', 'Foo 3'], [10.0, 20.0, 30.0]]
>>> Range('A10').horizontal.value
['Foo 1', 'Foo 2', 'Foo 3']
>>> Range('A10').vertical.value
['Foo 1', 10.0]


Note

Using these properties together with a named Range as top left cell gives you an extremely flexible setup in Excel: You can move around the table and change it’s size without having to adjust your code, e.g. by using something like Range('NamedRange').table.value.

## NumPy Arrays¶

NumPy arrays work similar to nested lists. However, empty cells are represented by nan instead of None. If you want to read in a Range as array, set the asarray keyword to True:

>>> import numpy as np
>>> wb = Workbook()
>>> Range('A1').value = np.eye(5)
>>> Range('A1', asarray=True).table.value
array([[ 1.,  0.,  0.,  0.,  0.],
[ 0.,  1.,  0.,  0.,  0.],
[ 0.,  0.,  1.,  0.,  0.],
[ 0.,  0.,  0.,  1.,  0.],
[ 0.,  0.,  0.,  0.,  1.]])


## Pandas DataFrames and Series¶

Pandas DataFrames and Series are also easy to work with:

• Series:

>>> import pandas as pd
>>> import numpy as np
>>> wb = Workbook()
>>> s = pd.Series([1.1, 3.3, 5., np.nan, 6., 8.])
>>> s
0    1.1
1    3.3
2    5.0
3    NaN
4    6.0
5    8.0
dtype: float64
>>> Range('A1').value = s
>>> data = Range('A1', asarray=True).table.value
>>> pd.Series(data[:,1], index=data[:,0])
0    1.1
1    3.3
2    5.0
3    NaN
4    6.0
5    8.0
dtype: float64

• DataFrame:

>>> wb = Workbook()
>>> Range('A1').value = [['one', 'two'], [1.1, 2.2], [3.3, None]]
>>> data = Range('A1').table.value
>>> df = pd.DataFrame(data[1:], columns=data[0])
>>> df
one  two
0  1.1  2.2
1  3.3  NaN
>>> Range('A5').value = df
>>> Range('A9', index=False).value = df  # Control index and header
>>> Range('A13', index=False, header=False).value = df


Note

You only need to specify the top left cell when writing a list, an NumPy array or a Pandas DataFrame to Excel, e.g.: Range('A1').value = np.eye(10)