Liam&#39;s link looks great, but also check out `pandas.Timedelta` - looks like it plays nicely with NumPy&#39;s and Python&#39;s time deltas.

https://pandas.pydata.org/pandas-docs/stable/timedeltas.html

    pd.date_range(&#39;2014-01-01&#39;, periods=10) + pd.Timedelta(days=1)

This one worked for me:

    &gt;&gt; print(df)
                              TotalVolume  Symbol
    2016-04-15 09:00:00       108400       2802.T
    2016-04-15 09:05:00       50300        2802.T

    &gt;&gt; print(df.set_index(pd.to_datetime(df.index.values) - datetime(2016, 4, 15)))

                 TotalVolume  Symbol
    09:00:00     108400       2802.T
    09:05:00     50300        2802.T


The Philippe solution but cleaner:

My subtraction data is: &#39;2018-09-22T11:05:00.000Z&#39;

    import datetime
    import pandas as pd
    
    df_modified = pd.to_datetime(df_reference.index.values) - datetime.datetime(2018, 9, 22, 11, 5, 0)



So I have been making an app, and everything has been working great. But today I made a new class like usual and for some reason in this class I can&#39;t access Public/Global variable from other classes. All the other classes can, but now when ever I try to make a new class I can&#39;t. How would this be fixed?

I am using Swift and Xcode 6.

Working Class:

    import UIKit
    import Foundation
    import Parse
    import CoreData

    var signedIn = true

    class ViewController: UIViewController {

New Class:

    import UIKit

    class NewClass: UIViewController {

        override func viewDidLoad() {
            super.viewDidLoad()

            signedIn = false
        
    }

But on `signedIn = false`

I get the error: 

&gt; use of unresolved identifier &quot;signedIn&quot;

&#39;Use of Unresolved Identifier&#39; in Swift

Is there is a good way to add a new value to existing `Stream`? All I can imagine is something like this:

    public &lt;T&gt; Stream&lt;T&gt; addToStream(Stream&lt;T&gt; stream, T elem ) {
        List&lt;T&gt; result = stream.collect(Collectors.toList());
        result.add(elem);
        return result.stream();
    }

But I&#39;m looking for something more concise that I can use in lambda expression without verbosity.

Another question appeared when I tried to implement _PECS_ principle:

    public &lt;T&gt; Stream&lt;? super T&gt; addToStream(Stream&lt;? super T&gt; stream, T elem ) {
        List&lt;? super T&gt; result = stream.collect(Collectors.toList()); //error
        result.add(elem);
        return result.stream();
    }

Seems like wildcard doesn&#39;t work with `Stream.collect` and I&#39;m wondering why. Thanks in advance.

Adding new value to existing Stream

I&#39;ve got a DataFrame who&#39;s index is just datetime.time and there&#39;s no method in  DataFrame.Index and datetime.time to shift the time. datetime.time has replace but that&#39;ll only work on individual items of the Series? 

Here&#39;s an example of the index used:
    
    In[526]:  dfa.index[:5]
    Out[526]: Index([21:12:19, 21:12:20, 21:12:21, 21:12:21, 21:12:22], dtype=&#39;object&#39;)

    In[527]:  type(dfa.index[0])
    Out[527]: datetime.time


How to add/subtract time (hours, minutes, etc.) from a Pandas DataFrame.Index whos objects are of type datetime.time?

I've got a DataFrame who's index is just datetime.time and there's no method in DataFrame.Index and datetime.time to shift the time. datetime.time has replace but that'll only work on individual items of the Series?
Here's an example of the index used:
<pre><code class="hljs language-ini">In[526]: dfa.index[:5]
Out[526]: Index([21:12:19, 21:12:20, 21:12:21, 21:12:21, 21:12:22], dtype='object')

In[527]: type(dfa.index[0])
Out[527]: datetime.time
</code></pre>

I am using pymongo to query for all items in a region (actually it is to query for all venues in a region on a map). I used `db.command(SON())` before to search in a spherical region, which can return me a dictionary and in the dictionary there is a key called `results` which contains the venues. Now I need to search in a square area and I am suggested to use `db.places.find`, however, this returns me a `pymongo.cursor.Cursor` class and I have no idea how to extract the venue results from it. 

Does anyone know whether I should convert the cursor into a dict and extract the results out, or use another method to query for items in a square region?
BTW, db is pymongo.database.Database class

The codes are:

    &gt;&gt;&gt; import pymongo
    &gt;&gt;&gt; db = pymongo.MongoClient(host).PSRC 
    &gt;&gt;&gt; resp = db.places.find({&quot;loc&quot;: {&quot;$within&quot;: {&quot;$box&quot;: [[ll_lng,ll_lat], [ur_lng,ur_lat]]}}})
    &gt;&gt;&gt; for doc in resp:
    &gt;&gt;&gt;     print(doc)

I have values of ll_lng, ll_lat, ur_lng and ur_lat, use these values but it prints nothing from this codes


How to convert a pymongo.cursor.Cursor into a dict?

Following along the PyMongo [tutorial][1] and am getting an error when calling the `insert_one` method on a collection.

	In [1]: import pymongo

	In [2]: from pymongo import MongoClient

	In [3]: client = MongoClient()

	In [4]: db = client.new_db

	In [5]: db
	Out[5]: Database(MongoClient(&#39;localhost&#39;, 27017), u&#39;new_db&#39;)

	In [6]: posts = db.posts

	In [7]: posts.insert_one({&#39;a&#39;:1})
	---------------------------------------------------------------------------
	TypeError                                 Traceback (most recent call last)
	&lt;ipython-input-7-2271c01f9a85&gt; in &lt;module&gt;()
	----&gt; 1 posts.insert_one({&#39;a&#39;:1})

	C:\Anaconda\lib\site-packages\pymongo-2.8-py2.7-win32.egg\pymongo\collection.py in __call__(self, *a
	rgs, **kwargs)
	   1771                         &quot;call the &#39;%s&#39; method on a &#39;Collection&#39; object it is &quot;
	   1772                         &quot;failing because no such method exists.&quot; %
	-&gt; 1773                         self.__name.split(&quot;.&quot;)[-1])

	TypeError: &#39;Collection&#39; object is not callable. If you meant to call the &#39;insert_one&#39; method on a &#39;Collection&#39; object it is failing because no such method exists.

There are a few posts online that discuss this error but all seem to be when the user calls a deprecated name.

Any guidance on what I am doing wrong here?

  [1]: http://api.mongodb.org/python/current/tutorial.html

Collection object is not callable error with PyMongo

I have a column in my dataframe like this:

    range
    &quot;(2,30)&quot;
    &quot;(50,290)&quot;
    &quot;(400,1000)&quot;
    ... 

and I want to replace the `,` comma with `-` dash. I&#39;m currently using this method but nothing is changed. 

    org_info_exc[&#39;range&#39;].replace(&#39;,&#39;, &#39;-&#39;, inplace=True)

Can anybody help?


How to replace text in a string column of a Pandas dataframe?

What is the BEST way to clear out all the `__pycache__`  folders and `.pyc/.pyo` files from a python3 project. I have seen multiple users suggest the `pyclean` script bundled with Debian, but this does not remove the folders. I want a simple way to clean up the project before pushing the files to my DVS.

Python3 project remove __pycache__ folders and .pyc files

I need to use the 

    (rdd.)partitionBy(npartitions, custom_partitioner)

 method that is not available on the DataFrame.  All of the DataFrame methods refer only to DataFrame results.  So then how to create an RDD from the DataFrame data?

Note: this is a change (in 1.3.0) from 1.2.0.

**Update** from the answer from @dpangmao: the method is .rdd. I was interested to understand if (a) it were public and (b) what are the performance implications.

Well (a) is yes and (b) - well you can see here that there are significant perf implications: a new RDD must be created  by invoking **mapPartitions** :

In **dataframe.py** (note the file name changed as well (was sql.py):

    @property
    def rdd(self):
        &quot;&quot;&quot;
        Return the content of the :class:`DataFrame` as an :class:`RDD`
        of :class:`Row` s.
        &quot;&quot;&quot;
        if not hasattr(self, &#39;_lazy_rdd&#39;):
            jrdd = self._jdf.javaToPython()
            rdd = RDD(jrdd, self.sql_ctx._sc, BatchedSerializer(PickleSerializer()))
            schema = self.schema

            def applySchema(it):
                cls = _create_cls(schema)
                return itertools.imap(cls, it)

            self._lazy_rdd = rdd.mapPartitions(applySchema)

        return self._lazy_rdd


How to convert a DataFrame back to normal RDD in pyspark?

Is there any difference between these:


	zonedDateTime.truncatedTo(ChronoUnit.DAYS);

	zonedDateTime.toLocalDate().atStartOfDay(zonedDateTime.getZone());

Any reason to prefer one against the other?

Thanks

Java 8 date-time: get start of day from ZonedDateTime

I have this timestamp value being return by a web service `&quot;2014-09-12T19:34:29Z&quot;`

I know that it means timezone, but what exactly does it mean? 

And I am trying to mock this web service, so is there a way to generate this timestamp using `strftime` in python?

Sorry if this is painfully obvious, but Google was not very helpful and neither was the `strftime()` reference page. 

I am currently using this :

    x.strftime(&quot;%Y-%m-%dT%H:%M:%S%Z&quot;)
    &#39;2015-03-26T10:58:51&#39;



What exactly does the T and Z mean in timestamp?

How can I convert `Gregorian date` to `Persian date` and vice-versa in `Python`?

[All I found][1] was some widgets and stuffs which will create Persian Calendar. I don&#39;t want a Persian calendar. I just want to convert dates to each other.
So how can I do that?


  [1]: https://github.com/behzadi/persianDatepicker

Convert Gregorian (Christian) date to Persian date and vice-versa in Python

I would like to get the current time in Python and assign them into variables like `year`, `month`, `day`, `hour`, `minute`. How can this be done in Python 2.7?

How to get current time in python and break up into year, month, day, hour, minute?

How should I transform from `datetime` to `string`? My attempt:

    dates = p.to_datetime(p.Series([&#39;20010101&#39;, &#39;20010331&#39;]), format = &#39;%Y%m%d&#39;)
    dates.str

datetime to string with series in pandas

I am trying to convert an am/pm format time to a 24 hour format time

    6:35 PM to 18:35

I tried this piece of code on playground but it doesn&#39;t seem to
work if I put the time alone

    let dateAsString = &quot;02/12/15, 6:35 PM&quot;
    let dateFormatter = NSDateFormatter()
    dateFormatter.dateFormat = &quot;HH&quot;
    let date = dateFormatter.dateFromString(dateAsString) //returns nil


Does anyone know how to accomplish this?

Xcode Swift am/pm time to 24 hour format

I need to create a simple but accurate timer.

This is my code:

    var seconds = 0;
    setInterval(function() {
    timer.innerHTML = seconds++;
    }, 1000);


After exactly 3600 seconds, it prints about 3500 seconds.

- Why is it not accurate?

- How can I create an accurate timer?



How to create an accurate timer in javascript?

I need some information about this date &#39;2015-05-12T00:00:00Z&#39;. What does it mean &#39;T&#39; and &#39;Z&#39;? Anyone can help me?I don&#39;t know how they mean. I need to convert this data in another format


        






 





   

What &#39;T&#39; and &#39;Z&#39; means in date

What is the difference between `performance.now()` and `Date.now()`?

Should I consider `performance.now()` as a replacement for `Date.now()` since `performace.now()` is more consistent and independent?

performance.now() vs Date.now()

I have a dataframe where one column is a list of groups each of my users belongs to. Something like:
    
    index groups  
    0     [&#39;a&#39;,&#39;b&#39;,&#39;c&#39;]
    1     [&#39;c&#39;]
    2     [&#39;b&#39;,&#39;c&#39;,&#39;e&#39;]
    3     [&#39;a&#39;,&#39;c&#39;]
    4     [&#39;b&#39;,&#39;e&#39;]
    
And what I would like to do is create a series of dummy columns to identify which groups each user belongs to in order to run some analyses

    index  a   b   c   d   e
    0      1   1   1   0   0
    1      0   0   1   0   0
    2      0   1   1   0   1
    3      1   0   1   0   0
    4      0   1   0   0   0


    pd.get_dummies(df[&#39;groups&#39;])
won&#39;t work because that just returns a column for each different list in my column.

The solution needs to be efficient as the dataframe will contain 500,000+ rows. Any advice would be appreciated!
     

Pandas convert a column of list to dummies

I have a `pandas` dataframe, `df`.

I want to select all indices in `df` that are **not** in a list, `blacklist.`

Now, I use list comprehension to create the desired labels to slice.

    ix=[i for i in df.index if i not in blacklist]  
    df_select=df.loc[ix]

Works fine, but may be clumsy if I need to do this often.

Is there a better way to do this?



Slice Pandas dataframe by index values that are (not) in a list

I have a dataframe with Multiindex and would like to modify one particular level of the Multiindex. For instance, the first level might be strings and I may want to remove the white spaces from that index level:

    df.index.levels[1] = [x.replace(&#39; &#39;, &#39;&#39;) for x in df.index.levels[1]]

However, the code above results in an error:

    TypeError: &#39;FrozenList&#39; does not support mutable operations.

I know I can reset_index and modify the column and then re-create the Multiindex, but I wonder whether there is a more elegant way to modify one particular level of the Multiindex directly.


Pandas: Modify a particular level of Multiindex

I&#39;m trying to apply a function to all rows of a pandas DataFrame (actually just one column in that DataFrame)

I&#39;m sure this is a syntax error but I&#39;m know sure what I&#39;m doing wrong

    df[&#39;col&#39;].apply(lambda x, y:(x - y).total_seconds(), args=[d1], axis=1)

The `col` column contains a bunch a `datetime.datetime` objects and and `d1` is the earliest of them.  I&#39;m trying to get a column of the total number of seconds for each of the rows

**EDIT** I keep getting the following error

    TypeError: &lt;lambda&gt;() got an unexpected keyword argument &#39;axis&#39;

I don&#39;t understand why `axis` is getting passed to my `lambda` function

**EDIT 2**

I&#39;ve also tried doing

    def diff_dates(d1, d2):
        return (d1-d2).total_seconds()

    df[&#39;col&#39;].apply(diff_dates, args=[d1], axis=1)

And I get the same error

Content Type	Original Author	Original Content on Stackoverflow
Question	Cameron Stark	View Question on Stackoverflow
Solution 1 - Python	Alex	View Answer on Stackoverflow
Solution 2 - Python	Philippe Remy	View Answer on Stackoverflow
Solution 3 - Python	Adam Kuzański	View Answer on Stackoverflow

How to add/subtract time (hours, minutes, etc.) from a Pandas DataFrame.Index whos objects are of type datetime.time?

Python Problem Overview

Python Solutions

Solution 1 - Python

Solution 2 - Python

Solution 3 - Python

Adding new value to existing Stream

'Use of Unresolved Identifier' in Swift

Attributions