Interactive online version:
Combining arrays
Import the LArray library:
[1]:
from larray import *
[2]:
# load the 'demography_eurostat' dataset
demography_eurostat = load_example_data('demography_eurostat')
# load 'gender' and 'time' axes
gender = demography_eurostat.gender
time = demography_eurostat.time
[3]:
# load the 'population' array from the 'demography_eurostat' dataset
population = demography_eurostat.population
# show 'population' array
population
[3]:
country gender\time 2013 2014 2015 2016 2017
Belgium Male 5472856 5493792 5524068 5569264 5589272
Belgium Female 5665118 5687048 5713206 5741853 5762455
France Male 31772665 32045129 32174258 32247386 32318973
France Female 33827685 34120851 34283895 34391005 34485148
Germany Male 39380976 39556923 39835457 40514123 40697118
Germany Female 41142770 41210540 41362080 41661561 41824535
[4]:
# load the 'population_benelux' array from the 'demography_eurostat' dataset
population_benelux = demography_eurostat.population_benelux
# show 'population_benelux' array
population_benelux
[4]:
country gender\time 2013 2014 2015 2016 2017
Belgium Male 5472856 5493792 5524068 5569264 5589272
Belgium Female 5665118 5687048 5713206 5741853 5762455
Luxembourg Male 268412 275117 281972 289193 296641
Luxembourg Female 268627 274563 280986 287056 294026
Netherlands Male 8307339 8334385 8372858 8417135 8475102
Netherlands Female 8472236 8494904 8527868 8561985 8606405
The LArray library offers several methods and functions to combine arrays:
insert: inserts an array in another array along an axis
append: adds an array at the end of an axis.
prepend: adds an array at the beginning of an axis.
extend: extends an array along an axis.
stack: combines several arrays along a new axis.
Insert
[5]:
other_countries = zeros((Axis('country=Luxembourg,Netherlands'), gender, time), dtype=int)
# insert new countries before 'France'
population_new_countries = population.insert(other_countries, before='France')
population_new_countries
[5]:
country gender\time 2013 2014 2015 2016 2017
Belgium Male 5472856 5493792 5524068 5569264 5589272
Belgium Female 5665118 5687048 5713206 5741853 5762455
Luxembourg Male 0 0 0 0 0
Luxembourg Female 0 0 0 0 0
Netherlands Male 0 0 0 0 0
Netherlands Female 0 0 0 0 0
France Male 31772665 32045129 32174258 32247386 32318973
France Female 33827685 34120851 34283895 34391005 34485148
Germany Male 39380976 39556923 39835457 40514123 40697118
Germany Female 41142770 41210540 41362080 41661561 41824535
[6]:
# insert new countries after 'France'
population_new_countries = population.insert(other_countries, after='France')
population_new_countries
[6]:
country gender\time 2013 2014 2015 2016 2017
Belgium Male 5472856 5493792 5524068 5569264 5589272
Belgium Female 5665118 5687048 5713206 5741853 5762455
France Male 31772665 32045129 32174258 32247386 32318973
France Female 33827685 34120851 34283895 34391005 34485148
Luxembourg Male 0 0 0 0 0
Luxembourg Female 0 0 0 0 0
Netherlands Male 0 0 0 0 0
Netherlands Female 0 0 0 0 0
Germany Male 39380976 39556923 39835457 40514123 40697118
Germany Female 41142770 41210540 41362080 41661561 41824535
See insert for more details and examples.
Append
Append one element to an axis of an array:
[7]:
# append data for 'Luxembourg'
population_new = population.append('country', population_benelux['Luxembourg'], 'Luxembourg')
population_new
[7]:
country gender\time 2013 2014 2015 2016 2017
Belgium Male 5472856 5493792 5524068 5569264 5589272
Belgium Female 5665118 5687048 5713206 5741853 5762455
France Male 31772665 32045129 32174258 32247386 32318973
France Female 33827685 34120851 34283895 34391005 34485148
Germany Male 39380976 39556923 39835457 40514123 40697118
Germany Female 41142770 41210540 41362080 41661561 41824535
Luxembourg Male 268412 275117 281972 289193 296641
Luxembourg Female 268627 274563 280986 287056 294026
The value being appended can have missing (or even extra) axes as long as common axes are compatible:
[8]:
population_lux = stack({'Male': -1, 'Female': 1}, gender)
population_lux
[8]:
gender Male Female
-1 1
[9]:
population_new = population.append('country', population_lux, 'Luxembourg')
population_new
[9]:
country gender\time 2013 2014 2015 2016 2017
Belgium Male 5472856 5493792 5524068 5569264 5589272
Belgium Female 5665118 5687048 5713206 5741853 5762455
France Male 31772665 32045129 32174258 32247386 32318973
France Female 33827685 34120851 34283895 34391005 34485148
Germany Male 39380976 39556923 39835457 40514123 40697118
Germany Female 41142770 41210540 41362080 41661561 41824535
Luxembourg Male -1 -1 -1 -1 -1
Luxembourg Female 1 1 1 1 1
The value being appended can also have the axis along which we are appending:
[10]:
population_nelux = population_benelux[['Netherlands', 'Luxembourg']]
population_nelux
[10]:
country gender\time 2013 2014 2015 2016 2017
Netherlands Male 8307339 8334385 8372858 8417135 8475102
Netherlands Female 8472236 8494904 8527868 8561985 8606405
Luxembourg Male 268412 275117 281972 289193 296641
Luxembourg Female 268627 274563 280986 287056 294026
[11]:
population_extended = population.append('country', population_nelux)
population_extended
[11]:
country gender\time 2013 2014 2015 2016 2017
Belgium Male 5472856 5493792 5524068 5569264 5589272
Belgium Female 5665118 5687048 5713206 5741853 5762455
France Male 31772665 32045129 32174258 32247386 32318973
France Female 33827685 34120851 34283895 34391005 34485148
Germany Male 39380976 39556923 39835457 40514123 40697118
Germany Female 41142770 41210540 41362080 41661561 41824535
Netherlands Male 8307339 8334385 8372858 8417135 8475102
Netherlands Female 8472236 8494904 8527868 8561985 8606405
Luxembourg Male 268412 275117 281972 289193 296641
Luxembourg Female 268627 274563 280986 287056 294026
See append for more details and examples.
Prepend
Prepend one element to an axis of an array:
[12]:
# append data for 'Luxembourg'
population_new = population.prepend('country', population_benelux['Luxembourg'], 'Luxembourg')
population_new
[12]:
country gender\time 2013 2014 2015 2016 2017
Luxembourg Male 268412 275117 281972 289193 296641
Luxembourg Female 268627 274563 280986 287056 294026
Belgium Male 5472856 5493792 5524068 5569264 5589272
Belgium Female 5665118 5687048 5713206 5741853 5762455
France Male 31772665 32045129 32174258 32247386 32318973
France Female 33827685 34120851 34283895 34391005 34485148
Germany Male 39380976 39556923 39835457 40514123 40697118
Germany Female 41142770 41210540 41362080 41661561 41824535
See prepend for more details and examples.
Stack
Stack several arrays together to create an entirely new dimension
[13]:
# imagine you have loaded data for each country in different arrays
# (e.g. loaded from different Excel sheets)
population_be = population['Belgium']
population_fr = population['France']
population_de = population['Germany']
print(population_be)
print(population_fr)
print(population_de)
gender\time 2013 2014 2015 2016 2017
Male 5472856 5493792 5524068 5569264 5589272
Female 5665118 5687048 5713206 5741853 5762455
gender\time 2013 2014 2015 2016 2017
Male 31772665 32045129 32174258 32247386 32318973
Female 33827685 34120851 34283895 34391005 34485148
gender\time 2013 2014 2015 2016 2017
Male 39380976 39556923 39835457 40514123 40697118
Female 41142770 41210540 41362080 41661561 41824535
[14]:
# create a new array with an extra axis 'country' by stacking the three arrays population_be/fr/de
population_stacked = stack({'Belgium': population_be, 'France': population_fr, 'Germany': population_de}, 'country')
population_stacked
[14]:
gender time\country Belgium France Germany
Male 2013 5472856 31772665 39380976
Male 2014 5493792 32045129 39556923
Male 2015 5524068 32174258 39835457
Male 2016 5569264 32247386 40514123
Male 2017 5589272 32318973 40697118
Female 2013 5665118 33827685 41142770
Female 2014 5687048 34120851 41210540
Female 2015 5713206 34283895 41362080
Female 2016 5741853 34391005 41661561
Female 2017 5762455 34485148 41824535
See stack for more details and examples.