table1 = [['foo', 'bar'],
['M', 12],
['F', 34],
['-', 56]]
from petl import addfield, look
look(table1)
# using a fixed value
table2 = addfield(table1, 'baz', 42)
look(table2)
# calculating the value
table2 = addfield(table1, 'baz', lambda rec: rec['bar'] * 2)
look(table2)
# an expression string can also be used via expr
from petl import expr
table3 = addfield(table1, 'baz', expr('{bar} * 2'))
look(table3)
# rowslice
table1 = [['foo', 'bar'],
['a', 1],
['b', 2],
['c', 5],
['d', 7],
['f', 42]]
from petl import rowslice, look
look(table1)
table2 = rowslice(table1, 2)
table1 = [['foo', 'bar'],
['M', 12],
['F', 34],
['-', 56]]
from petl import addfield, look
look(table1)
# using a fixed value
table2 = addfield(table1, 'baz', 42)
look(table2)
# calculating the value
table2 = addfield(table1, 'baz', lambda rec: rec['bar'] * 2)
look(table2)
# an expression string can also be used via expr
from petl import expr
table3 = addfield(table1, 'baz', expr('{bar} * 2'))
look(table3)
# rowslice
table1 = [['foo', 'bar'],
['a', 1],
['b', 2],
['c', 5],
['d', 7],
['f', 42]]
from petl import rowslice, look
look(table1)
table2 = rowslice(table1, 2)
table1 = [['foo', 'bar'],
['M', 12],
['F', 34],
['-', 56]]
from petl import extend, look
look(table1)
# using a fixed value
table2 = extend(table1, 'baz', 42)
look(table2)
# calculating the value
table2 = extend(table1, 'baz', lambda rec: rec['bar'] * 2)
look(table2)
# an expression string can also be used via expr
from petl import expr
table3 = extend(table1, 'baz', expr('{bar} * 2'))
look(table3)
# rowslice
table1 = [['foo', 'bar'],
['a', 1],
['b', 2],
['c', 5],
['d', 7],
['f', 42]]
from petl import rowslice, look
look(table1)
table2 = rowslice(table1, 2)
table1 = [['foo', 'bar'], ['M', 12], ['F', 34], ['-', 56]]
from petl import extend, look
look(table1)
# using a fixed value
table2 = extend(table1, 'baz', 42)
look(table2)
# calculating the value
table2 = extend(table1, 'baz', lambda rec: rec['bar'] * 2)
look(table2)
# an expression string can also be used via expr
from petl import expr
table3 = extend(table1, 'baz', expr('{bar} * 2'))
look(table3)
# rowslice
table1 = [['foo', 'bar'], ['a', 1], ['b', 2], ['c', 5], ['d', 7], ['f', 42]]
from petl import rowslice, look
look(table1)
table2 = rowslice(table1, 2)
look(table2)
table3 = rowslice(table1, 1, 4)
look(table3)
table4 = rowslice(table1, 0, 5, 2)
look(table4)
def addfield(data, source, field, value):
"""Return the first n rows of the data table and store them in the destination data table."""
s = data.get(source)
s = s.addfield(field, petl.expr(value))
data.set(source, s)
