Interactive online version:
Some Useful Functions¶
Import the LArray library:
[1]:
from larray import *
[2]:
# load 'demography_eurostat' dataset
demo_eurostat = load_example_data('demography_eurostat')
# extract the 'pop' array from the dataset
pop = demo_eurostat.pop
pop
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
<ipython-input-2-ce337d55681e> in <module>
1 # load 'demography_eurostat' dataset
----> 2 demo_eurostat = load_example_data('demography_eurostat')
3
4 # extract the 'pop' array from the dataset
5 pop = demo_eurostat.pop
~/checkouts/readthedocs.org/user_builds/larray/conda/0.32/lib/python3.6/site-packages/larray-0.32-py3.6.egg/larray/example.py in load_example_data(name)
91 if name not in AVAILABLE_EXAMPLE_DATA.keys():
92 raise ValueError("example_data must be chosen from list {}".format(list(AVAILABLE_EXAMPLE_DATA.keys())))
---> 93 return la.Session(AVAILABLE_EXAMPLE_DATA[name])
~/checkouts/readthedocs.org/user_builds/larray/conda/0.32/lib/python3.6/site-packages/larray-0.32-py3.6.egg/larray/core/session.py in __init__(self, *args, **kwargs)
94 if isinstance(a0, str):
95 # assume a0 is a filename
---> 96 self.load(a0)
97 else:
98 # iterable of tuple or dict-like
~/checkouts/readthedocs.org/user_builds/larray/conda/0.32/lib/python3.6/site-packages/larray-0.32-py3.6.egg/larray/core/session.py in load(self, fname, names, engine, display, **kwargs)
426 else:
427 handler = handler_cls(fname)
--> 428 metadata, objects = handler.read(names, display=display, **kwargs)
429 for k, v in objects.items():
430 self[k] = v
~/checkouts/readthedocs.org/user_builds/larray/conda/0.32/lib/python3.6/site-packages/larray-0.32-py3.6.egg/larray/inout/common.py in read(self, keys, *args, **kwargs)
128 print("loading", type, "object", key, "...", end=' ')
129 try:
--> 130 res[key] = self._read_item(key, type, *args, **kwargs)
131 except Exception:
132 if not ignore_exceptions:
~/checkouts/readthedocs.org/user_builds/larray/conda/0.32/lib/python3.6/site-packages/larray-0.32-py3.6.egg/larray/inout/hdf.py in _read_item(self, key, type, *args, **kwargs)
137 else:
138 raise TypeError()
--> 139 return read_hdf(self.handle, hdf_key, *args, **kwargs)
140
141 def _dump_item(self, key, value, *args, **kwargs):
~/checkouts/readthedocs.org/user_builds/larray/conda/0.32/lib/python3.6/site-packages/larray-0.32-py3.6.egg/larray/inout/hdf.py in read_hdf(filepath_or_buffer, key, fill_value, na, sort_rows, sort_columns, name, **kwargs)
81 cartesian_prod = writer != 'LArray'
82 res = df_asarray(pd_obj, sort_rows=sort_rows, sort_columns=sort_columns, fill_value=fill_value,
---> 83 parse_header=False, cartesian_prod=cartesian_prod)
84 if _meta is not None:
85 res.meta = _meta
~/checkouts/readthedocs.org/user_builds/larray/conda/0.32/lib/python3.6/site-packages/larray-0.32-py3.6.egg/larray/inout/pandas.py in df_asarray(df, sort_rows, sort_columns, raw, parse_header, wide, cartesian_prod, **kwargs)
338 unfold_last_axis_name = isinstance(axes_names[-1], basestring) and '\\' in axes_names[-1]
339 res = from_frame(df, sort_rows=sort_rows, sort_columns=sort_columns, parse_header=parse_header,
--> 340 unfold_last_axis_name=unfold_last_axis_name, cartesian_prod=cartesian_prod, **kwargs)
341
342 # ugly hack to avoid anonymous axes converted as axes with name 'Unnamed: x' by pandas
~/checkouts/readthedocs.org/user_builds/larray/conda/0.32/lib/python3.6/site-packages/larray-0.32-py3.6.egg/larray/inout/pandas.py in from_frame(df, sort_rows, sort_columns, parse_header, unfold_last_axis_name, fill_value, meta, cartesian_prod, **kwargs)
241 raise ValueError('sort_rows and sort_columns cannot not be used when cartesian_prod is set to False. '
242 'Please call the method sort_axes on the returned array to sort rows or columns')
--> 243 axes_labels = index_to_labels(df.index, sort=False)
244
245 # Pandas treats column labels as column names (strings) so we need to convert them to values
~/checkouts/readthedocs.org/user_builds/larray/conda/0.32/lib/python3.6/site-packages/larray-0.32-py3.6.egg/larray/inout/pandas.py in index_to_labels(idx, sort)
41 Returns unique labels for each dimension.
42 """
---> 43 if isinstance(idx, pd.core.index.MultiIndex):
44 if sort:
45 return list(idx.levels)
AttributeError: module 'pandas.core' has no attribute 'index'
with total¶
Add totals to one or several axes:
[3]:
pop.with_total('gender', label='Total')
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
<ipython-input-3-d5ae827e7ef1> in <module>
----> 1 pop.with_total('gender', label='Total')
NameError: name 'pop' is not defined
See with_total for more details and examples.
where¶
The where function can be used to apply some computation depending on a condition:
[4]:
# where(condition, value if true, value if false)
where(pop < pop.mean('time'), -pop, pop)
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
<ipython-input-4-05a575f73c29> in <module>
1 # where(condition, value if true, value if false)
----> 2 where(pop < pop.mean('time'), -pop, pop)
NameError: name 'pop' is not defined
See where for more details and examples.
clip¶
Set all data between a certain range:
[5]:
# values below 10 millions are set to 10 millions
pop.clip(minval=10**7)
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
<ipython-input-5-13053b977351> in <module>
1 # values below 10 millions are set to 10 millions
----> 2 pop.clip(minval=10**7)
NameError: name 'pop' is not defined
[6]:
# values above 40 millions are set to 40 millions
pop.clip(maxval=4*10**7)
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
<ipython-input-6-e0b0b4c8bb9c> in <module>
1 # values above 40 millions are set to 40 millions
----> 2 pop.clip(maxval=4*10**7)
NameError: name 'pop' is not defined
[7]:
# values below 10 millions are set to 10 millions and
# values above 40 millions are set to 40 millions
pop.clip(10**7, 4*10**7)
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
<ipython-input-7-ba0330376a84> in <module>
1 # values below 10 millions are set to 10 millions and
2 # values above 40 millions are set to 40 millions
----> 3 pop.clip(10**7, 4*10**7)
NameError: name 'pop' is not defined
See clip for more details and examples.
divnot0¶
Replace division by 0 by 0:
[8]:
divisor = ones(pop.axes, dtype=int)
divisor['Male'] = 0
divisor
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
<ipython-input-8-4dc88d9626bf> in <module>
----> 1 divisor = ones(pop.axes, dtype=int)
2 divisor['Male'] = 0
3 divisor
NameError: name 'pop' is not defined
[9]:
pop / divisor
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
<ipython-input-9-75d7cd731c57> in <module>
----> 1 pop / divisor
NameError: name 'pop' is not defined
[10]:
# we use astype(int) since the divnot0 method
# returns a float array in this case while
# we want an integer array
pop.divnot0(divisor).astype(int)
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
<ipython-input-10-864c0d271282> in <module>
2 # returns a float array in this case while
3 # we want an integer array
----> 4 pop.divnot0(divisor).astype(int)
NameError: name 'pop' is not defined
See divnot0 for more details and examples.
ratio¶
The ratio (rationot0) method returns an array with all values divided by the sum of values along given axes:
[11]:
pop.ratio('gender')
# which is equivalent to
pop / pop.sum('gender')
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
<ipython-input-11-0468caf179b2> in <module>
----> 1 pop.ratio('gender')
2
3 # which is equivalent to
4 pop / pop.sum('gender')
NameError: name 'pop' is not defined
percents¶
[12]:
# or, if you want the previous ratios in percents
pop.percent('gender')
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
<ipython-input-12-25393219a8df> in <module>
1 # or, if you want the previous ratios in percents
----> 2 pop.percent('gender')
NameError: name 'pop' is not defined
See percent for more details and examples.
diff¶
The diff method calculates the n-th order discrete difference along a given axis.
The first order difference is given by out[n+1] = in[n+1] - in[n] along the given axis.
[13]:
# calculates 'diff[year+1] = pop[year+1] - pop[year]'
pop.diff('time')
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
<ipython-input-13-8de85c6279ec> in <module>
1 # calculates 'diff[year+1] = pop[year+1] - pop[year]'
----> 2 pop.diff('time')
NameError: name 'pop' is not defined
[14]:
# calculates 'diff[year+2] = pop[year+2] - pop[year]'
pop.diff('time', d=2)
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
<ipython-input-14-52d4a8a02e05> in <module>
1 # calculates 'diff[year+2] = pop[year+2] - pop[year]'
----> 2 pop.diff('time', d=2)
NameError: name 'pop' is not defined
[15]:
# calculates 'diff[year] = pop[year+1] - pop[year]'
pop.diff('time', label='lower')
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
<ipython-input-15-ac9f0715f28c> in <module>
1 # calculates 'diff[year] = pop[year+1] - pop[year]'
----> 2 pop.diff('time', label='lower')
NameError: name 'pop' is not defined
See diff for more details and examples.
growth_rate¶
The growth_rate method calculates the growth along a given axis.
It is roughly equivalent to a.diff(axis, d, label) / a[axis.i[:-d]]:
[16]:
pop.growth_rate('time')
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
<ipython-input-16-745057b9829b> in <module>
----> 1 pop.growth_rate('time')
NameError: name 'pop' is not defined
See growth_rate for more details and examples.
shift¶
The shift method drops first label of an axis and shifts all subsequent labels
[17]:
pop.shift('time')
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
<ipython-input-17-f61f4cde41a9> in <module>
----> 1 pop.shift('time')
NameError: name 'pop' is not defined
[18]:
# when shift is applied on an (increasing) time axis,
# it effectively brings "past" data into the future
pop_shifted = pop.shift('time')
stack({'pop_shifted_2014': pop_shifted[2014], 'pop_2013': pop[2013]}, 'array')
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
<ipython-input-18-c18dcab698a8> in <module>
1 # when shift is applied on an (increasing) time axis,
2 # it effectively brings "past" data into the future
----> 3 pop_shifted = pop.shift('time')
4 stack({'pop_shifted_2014': pop_shifted[2014], 'pop_2013': pop[2013]}, 'array')
NameError: name 'pop' is not defined
See shift for more details and examples.
Other interesting functions¶
There are a lot more interesting functions that you can find in the API reference in sections Aggregation Functions, Miscellaneous and Utility Functions.