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from __future__ import division, print_function, absolute_import
# cut()
#######
import petl as etl
table1 = [['foo', 'bar', 'baz'],
['A', 1, 2.7],
['B', 2, 3.4],
['B', 3, 7.8],
['D', 42, 9.0],
['E', 12]]
table2 = etl.cut(table1, 'foo', 'baz')
table2
# fields can also be specified by index, starting from zero
table3 = etl.cut(table1, 0, 2)
table3
# field names and indices can be mixed
table4 = etl.cut(table1, 'bar', 0)
table4
# select a range of fields
table5 = etl.cut(table1, *range(0, 2))
table5
# cutout()
##########
import petl as etl
table1 = [['foo', 'bar', 'baz'],
['A', 1, 2.7],
['B', 2, 3.4],
['B', 3, 7.8],
['D', 42, 9.0],
['E', 12]]
table2 = etl.cutout(table1, 'bar')
table2
# cat()
#######
import petl as etl
table1 = [['foo', 'bar'],
[1, 'A'],
[2, 'B']]
table2 = [['bar', 'baz'],
['C', True],
['D', False]]
table3 = etl.cat(table1, table2)
table3
# can also be used to square up a single table with uneven rows
table4 = [['foo', 'bar', 'baz'],
['A', 1, 2],
['B', '2', '3.4'],
[u'B', u'3', u'7.8', True],
['D', 'xyz', 9.0],
['E', None]]
table5 = etl.cat(table4)
table5
# use the header keyword argument to specify a fixed set of fields
table6 = [['bar', 'foo'],
['A', 1],
['B', 2]]
table7 = etl.cat(table6, header=['A', 'foo', 'B', 'bar', 'C'])
table7
# using the header keyword argument with two input tables
table8 = [['bar', 'foo'],
['A', 1],
['B', 2]]
table9 = [['bar', 'baz'],
['C', True],
['D', False]]
table10 = etl.cat(table8, table9, header=['A', 'foo', 'B', 'bar', 'C'])
table10
# addfield()
############
import petl as etl
table1 = [['foo', 'bar'],
['M', 12],
['F', 34],
['-', 56]]
# using a fixed value
table2 = etl.addfield(table1, 'baz', 42)
table2
# calculating the value
table2 = etl.addfield(table1, 'baz', lambda rec: rec['bar'] * 2)
table2
# rowslice()
############
import petl as etl
table1 = [['foo', 'bar'],
['a', 1],
['b', 2],
['c', 5],
['d', 7],
['f', 42]]
table2 = etl.rowslice(table1, 2)
table2
table3 = etl.rowslice(table1, 1, 4)
table3
table4 = etl.rowslice(table1, 0, 5, 2)
table4
# head()
########
import petl as etl
table1 = [['foo', 'bar'],
['a', 1],
['b', 2],
['c', 5],
['d', 7],
['f', 42],
['f', 3],
['h', 90]]
table2 = etl.head(table1, 4)
table2
# tail()
########
import petl as etl
table1 = [['foo', 'bar'],
['a', 1],
['b', 2],
['c', 5],
['d', 7],
['f', 42],
['f', 3],
['h', 90],
['k', 12],
['l', 77],
['q', 2]]
table2 = etl.tail(table1, 4)
table2
# skipcomments()
################
import petl as etl
table1 = [['##aaa', 'bbb', 'ccc'],
['##mmm',],
['#foo', 'bar'],
['##nnn', 1],
['a', 1],
['b', 2]]
table2 = etl.skipcomments(table1, '##')
table2
# annex()
#########
import petl as etl
table1 = [['foo', 'bar'],
['A', 9],
['C', 2],
['F', 1]]
table2 = [['foo', 'baz'],
['B', 3],
['D', 10]]
table3 = etl.annex(table1, table2)
table3
# addrownumbers()
#################
import petl as etl
table1 = [['foo', 'bar'],
['A', 9],
['C', 2],
['F', 1]]
table2 = etl.addrownumbers(table1)
table2
# addcolumn()
#############
import petl as etl
table1 = [['foo', 'bar'],
['A', 1],
['B', 2]]
col = [True, False]
table2 = etl.addcolumn(table1, 'baz', col)
table2
# addfieldusingcontext()
########################
import petl as etl
table1 = [['foo', 'bar'],
['A', 1],
['B', 4],
['C', 5],
['D', 9]]
def upstream(prv, cur, nxt):
if prv is None:
return None
else:
return cur.bar - prv.bar
def downstream(prv, cur, nxt):
if nxt is None:
return None
else:
return nxt.bar - cur.bar
table2 = etl.addfieldusingcontext(table1, 'baz', upstream)
table3 = etl.addfieldusingcontext(table2, 'quux', downstream)
table3
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