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den-run-ai opened this issue Apr 1, 2016 · 4 comments
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API: Index.map should return Index rather than array #12766

den-run-ai opened this issue Apr 1, 2016 · 4 comments
Labels
API Design Compat pandas objects compatability with Numpy or Python functions
Milestone
0.20.0

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@den-run-ai
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df2=pd.DataFrame([[0,1],[2,3]],columns=['c1','c2'],index=['i1','i2'])
df2.index.name='index'
df2.to_html()
<table border="1" class="dataframe">\n  <thead>\n    <tr style="text-align: right;">\n      <th></th>\n      <th>c1</th>\n      <th>c2</th>\n    </tr>\n    <tr>\n      <th>index</th>\n      <th></th>\n      <th></th>\n    </tr>\n  </thead>\n  <tbody>\n    <tr>\n      <th>i1</th>\n      <td>0</td>\n      <td>1</td>\n    </tr>\n    <tr>\n      <th>i2</th>\n      <td>2</td>\n      <td>3</td>\n    </tr>\n  </tbody>\n</table>
df2.index = df2.index.map(lambda x: x.upper())
df2.to_html()
<table border="1" class="dataframe">\n  <thead>\n    <tr style="text-align: right;">\n      <th></th>\n      <th>c1</th>\n      <th>c2</th>\n    </tr>\n  </thead>\n  <tbody>\n    <tr>\n      <th>I1</th>\n      <td>0</td>\n      <td>1</td>\n    </tr>\n    <tr>\n      <th>I2</th>\n      <td>2</td>\n      <td>3</td>\n    </tr>\n  </tbody>\n</table>

I think map should accept inplace

INSTALLED VERSIONS
------------------
commit: None
python: 2.7.11.final.0
python-bits: 64
OS: Windows
OS-release: 7
machine: AMD64
processor: Intel64 Family 6 Model 60 Stepping 3, GenuineIntel
byteorder: little
LC_ALL: None
LANG: None

pandas: 0.18.0
nose: 1.3.7
pip: 8.1.1
setuptools: 18.2
Cython: None
numpy: 1.10.4
scipy: 0.17.0
statsmodels: None
xarray: None
IPython: 4.1.2
sphinx: None
patsy: None
dateutil: 2.5.1
pytz: 2016.2
blosc: None
bottleneck: 1.0.0
tables: None
numexpr: 2.5
matplotlib: 1.5.1
openpyxl: None
xlrd: None
xlwt: None
xlsxwriter: None
lxml: None
bs4: None
html5lib: None
httplib2: None
apiclient: None
sqlalchemy: 1.0.12
pymysql: None
psycopg2: None
jinja2: 2.8
boto: None
@jreback jreback mentioned this issue Apr 1, 2016
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@jreback
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jreback commented Apr 1, 2016

.map return an array, not an Index. So if that is fixed then this would work.

@denfromufa pr's welcome.

@jreback jreback added API Design Compat pandas objects compatability with Numpy or Python functions labels Apr 1, 2016
@jreback jreback added this to the Next Major Release milestone Apr 1, 2016
@jreback jreback changed the title pandas map looses index name API: Index.map should return Index rather than array Apr 1, 2016
@jreback jreback modified the milestones: 0.19.0, Next Major Release Apr 1, 2016
@jreback
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jreback commented Apr 1, 2016

inplace is not acceptable for an immutable object.

@jrings
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jrings commented Apr 5, 2016

Not sure if it's that easy, but seemed like a good start to contribute something.
Putting in a PR, I just turn it into Index before returning?

@jrings jrings mentioned this issue Apr 5, 2016
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@den-run-ai
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Go for it! :)

Yes it should be that simple!

On Monday, April 4, 2016, Joerg Rings [email protected] wrote:

Not sure if it's that easy, but seemed like a good start to contribute
something.
Putting in a PR, I just turn it into Index before returning?

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#12766 (comment)

@Khris777 Khris777 mentioned this issue Oct 26, 2016
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@nateyoder nateyoder mentioned this issue Oct 26, 2016
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ischurov pushed a commit to ischurov/pandas that referenced this issue Dec 19, 2016
@nateyoder @ischurov
API: map() on Index returns an Index, not array
1b61ce9 
closes pandas-dev#12766
closes pandas-dev#12798

This is a follow on to pandas-dev#12798.

Author: Nate Yoder <[email protected]>

Closes pandas-dev#14506 from nateyoder/index_map_index and squashes the following commits:

95e4440 [Nate Yoder] fix typo and add ref tag in whatsnew
b36e83c [Nate Yoder] update whatsnew, fix documentation
4635e6a [Nate Yoder] compare as index
a17ddab [Nate Yoder] Fix unused import and docstrings per pep8radius docformatter; change other uses of assert_index_equal to testing instead os self
ab168e7 [Nate Yoder] Update whatsnew and add git PR to tests to denote changes
504c2a2 [Nate Yoder] Fix tests that weren't run by PyCharm
23c133d [Nate Yoder] Update tests to match dtype int64
07b772a [Nate Yoder] use the numpy results if we can to avoid repeating the computation just to create the object
a110be9 [Nate Yoder] make map on time tseries indices return index if dtype of output is not a tseries; sphinx changes; fix docstring
a596744 [Nate Yoder] introspect results from map so that if the output array has tuples we create a multiindex instead of an index
5fc66c3 [Nate Yoder] make map return an index if it operates on an index, multi index, or categorical index; map on a categorical will either return a categorical or an index (rather than a numpy array)
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@jreback @jrings @den-run-ai