ENH: Add Styler.where #17474

Licht-T · 2017-09-08T08:26:57Z

closes API: Add Styler.where #16255
tests added / passed
Added test_where_subset in pandas/tests/io/formats/test_style.py.
passes git diff upstream/master -u -- "*.py" | flake8 --diff
whatsnew entry
It makes the redundant style condition simple.

df.style.applymap(lambda val: 'color: %s' % 'red' if val < 0 else 'black')
df.style.where(lambda val: val < 0, 'color: red', 'color: black')

pep8speaks · 2017-09-08T08:27:01Z

Hello @Licht-T! Thanks for updating the PR.

Cheers ! There are no PEP8 issues in this Pull Request. 🍻

Comment last updated on September 10, 2017 at 14:48 Hours UTC

codecov · 2017-09-08T09:16:29Z

Codecov Report

Merging #17474 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #17474      +/-   ##
==========================================
- Coverage   91.16%   91.14%   -0.02%     
==========================================
  Files         163      163              
  Lines       49561    49561              
==========================================
- Hits        45180    45171       -9     
- Misses       4381     4390       +9

Flag	Coverage Δ
#multiple	`88.92% <ø> (ø)`	⬆️
#single	`40.23% <ø> (-0.07%)`	⬇️

Impacted Files	Coverage Δ
pandas/io/formats/style.py	`100% <ø> (ø)`	⬆️
pandas/io/gbq.py	`25% <0%> (-58.34%)`	⬇️
pandas/core/frame.py	`97.72% <0%> (-0.1%)`	⬇️

Continue to review full report at Codecov.

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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codecov · 2017-09-08T09:16:43Z

Codecov Report

Merging #17474 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #17474      +/-   ##
==========================================
- Coverage   91.15%   91.13%   -0.02%     
==========================================
  Files         163      163              
  Lines       49534    49534              
==========================================
- Hits        45153    45144       -9     
- Misses       4381     4390       +9

Flag	Coverage Δ
#multiple	`88.92% <ø> (ø)`	⬆️
#single	`40.22% <ø> (-0.07%)`	⬇️

Impacted Files	Coverage Δ
pandas/io/formats/style.py	`100% <ø> (ø)`	⬆️
pandas/io/gbq.py	`25% <0%> (-58.34%)`	⬇️
pandas/core/frame.py	`97.72% <0%> (-0.1%)`	⬇️

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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jreback

can you add a whatsnew note on Other Enahancements as well as use this in the notebook where appropriate

jreback · 2017-09-08T10:07:13Z

pandas/io/formats/style.py

+        """
+        Apply a function elementwise, updating the HTML
+        representation with a style which is selected in
+        accordance with the return value of a function.


add a versionadded tag

jreback · 2017-09-08T10:07:37Z

pandas/io/formats/style.py

@@ -623,6 +623,32 @@ def applymap(self, func, subset=None, **kwargs):
                           (func, subset), kwargs))
        return self

+    def where(self, func, style1, style2='', subset=None, **kwargs):
+        """


defaults should be None not ''

jreback · 2017-09-08T10:07:57Z

pandas/io/formats/style.py

+
+        Parameters
+        ----------
+        func : function


jreback · 2017-09-08T10:08:26Z

pandas/io/formats/style.py

+        ----------
+        func : function
+            ``func`` should take a scalar and return a boolean
+        style1 : a style applied when ``func`` returns true


style1: str
when applied......

jreback · 2017-09-08T10:09:05Z

pandas/tests/io/formats/test_style.py

@@ -265,6 +265,26 @@ def f(x):
                            col in self.df.loc[slice_].columns)
            assert result == expected

+    def test_where_subset(self):
+        def f(x):


add a comment with the issue number (this PR number)

TomAugspurger · 2017-09-08T11:20:11Z

pandas/tests/io/formats/test_style.py

+        for slice_ in slices:
+            result = self.df.style.where(f, style1, style2,
+                                         subset=slice_)._compute().ctx
+            expected = self.df.style.applymap(g, subset=slice_)._compute().ctx


These tests are fine, but could you add one test that checks the generated values directly against the dictionary?

Licht-T · 2017-09-09T07:27:39Z

@jreback @TomAugspurger Thanks for your review. Fixed and added some new tests.

Licht-T · 2017-09-09T16:08:58Z

Travis CI seems not work well due to its own error.
Could someone restart the Travis CI build?

jreback

this seems ok, @TomAugspurger . do we have a section in api.rst for things like this?

jreback · 2017-09-09T16:58:46Z

doc/source/whatsnew/v0.21.0.txt

@@ -112,6 +112,7 @@ Other Enhancements
 - `read_*` methods can now infer compression from non-string paths, such as ``pathlib.Path`` objects (:issue:`17206`).
 - :func:`pd.read_sas()` now recognizes much more of the most frequently used date (datetime) formats in SAS7BDAT files (:issue:`15871`).
 - :func:`DataFrame.items` and :func:`Series.items` is now present in both Python 2 and 3 and is lazy in all cases (:issue:`13918`, :issue:`17213`)
+- :func:`Styler.where` has been implemented. It enables simple DataFrame styling on the Jupyter notebook (:issue:`17474`).


pls label this as a convenience for Styler.applymap

jreback · 2017-09-09T17:00:22Z

pandas/io/formats/style.py

+
+        Parameters
+        ----------
+        func : callable


this should mimic the signature of DataFrame.where as much as possible

func -> cond
style1 -> value
style2 -> other

Licht-T · 2017-09-10T05:00:30Z

@jreback Thanks for your suggestion. Fixed!

jreback · 2017-09-10T14:24:58Z

doc/source/whatsnew/v0.21.0.txt

@@ -112,6 +112,7 @@ Other Enhancements
 - `read_*` methods can now infer compression from non-string paths, such as ``pathlib.Path`` objects (:issue:`17206`).
 - :func:`pd.read_sas()` now recognizes much more of the most frequently used date (datetime) formats in SAS7BDAT files (:issue:`15871`).
 - :func:`DataFrame.items` and :func:`Series.items` is now present in both Python 2 and 3 and is lazy in all cases (:issue:`13918`, :issue:`17213`)
+- :func:`Styler.where` has been implemented. It is as a convenience for Styler.applymap and enables simple DataFrame styling on the Jupyter notebook (:issue:`17474`).


use :func:`Styler.applymap` as well

jreback · 2017-09-10T14:25:40Z

pandas/io/formats/style.py

+
+        Returns
+        -------
+        self : Styler


can you add a See Also here (pointing to .applymap) and the reciprical one there

jreback · 2017-09-10T14:26:34Z

doc/source/whatsnew/v0.21.0.txt

@@ -112,6 +112,7 @@ Other Enhancements
 - `read_*` methods can now infer compression from non-string paths, such as ``pathlib.Path`` objects (:issue:`17206`).
 - :func:`pd.read_sas()` now recognizes much more of the most frequently used date (datetime) formats in SAS7BDAT files (:issue:`15871`).
 - :func:`DataFrame.items` and :func:`Series.items` is now present in both Python 2 and 3 and is lazy in all cases (:issue:`13918`, :issue:`17213`)
+- :func:`Styler.where` has been implemented. It is as a convenience for Styler.applymap and enables simple DataFrame styling on the Jupyter notebook (:issue:`17474`).




.where needs to be added to api.rst

Licht-T · 2017-09-10T14:49:29Z

@jreback Thanks. All is now fixed.

jreback · 2017-09-11T00:02:20Z

thanks @Licht-T

If you'd have a pass thru the actual documentation notebook and make a PR for anything where we should logically use .where to make the syntax more clear would be great (or indicate that it looks good).

Licht-T force-pushed the styler-where branch from c386656 to 9cf48fb Compare September 8, 2017 08:33

jreback requested changes Sep 8, 2017

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jreback added the Output-Formatting __repr__ of pandas objects, to_string label Sep 8, 2017

TomAugspurger reviewed Sep 8, 2017

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Licht-T force-pushed the styler-where branch from 9cf48fb to c6dc109 Compare September 9, 2017 05:37

jreback approved these changes Sep 9, 2017

View reviewed changes

Licht-T force-pushed the styler-where branch from e534c8b to 5f513db Compare September 10, 2017 04:57

jreback requested changes Sep 10, 2017

View reviewed changes

Licht-T force-pushed the styler-where branch from 5f513db to 9542138 Compare September 10, 2017 14:41

Licht-T added 5 commits September 10, 2017 23:47

ENH: Implement Styler.where

2282acd

TST: Add Styler.where test

8863779

DOC: Add the description of Styler.where on whatsnew note

78d2cc4

DOC: Add the reference to Styler.where on api.rst

781337c

DOC: Add the reference to Styler.where on Styler.applymap document

82ae1dc

Licht-T force-pushed the styler-where branch from 9542138 to 82ae1dc Compare September 10, 2017 14:48

TomAugspurger approved these changes Sep 10, 2017

View reviewed changes

jreback added this to the 0.21.0 milestone Sep 11, 2017

jreback approved these changes Sep 11, 2017

View reviewed changes

jreback merged commit 42ed4f1 into pandas-dev:master Sep 11, 2017

alanbato pushed a commit to alanbato/pandas that referenced this pull request Nov 10, 2017

ENH: Add Styler.where (pandas-dev#17474)

2b9c57f

No-Stream pushed a commit to No-Stream/pandas that referenced this pull request Nov 28, 2017

ENH: Add Styler.where (pandas-dev#17474)

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ENH: Add Styler.where #17474

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ENH: Add Styler.where #17474

ENH: Add Styler.where #17474

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