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How to add an empty column to a dataframe?
...p
>>> import pandas as pd
>>> df = pd.DataFrame({"A": [1,2,3], "B": [2,3,4]})
>>> df
A B
0 1 2
1 2 3
2 3 4
>>> df["C"] = ""
>>> df["D"] = np.nan
>>> df
A B C D
0 1 2 NaN
1 2 3 NaN
2 3 4 NaN
...
How do I compare two DateTime objects in PHP 5.2.8?
...
<?php
date_default_timezone_set('Europe/London');
$d1 = new DateTime('2008-08-03 14:52:10');
$d2 = new DateTime('2008-01-03 11:11:10');
var_dump($d1 == $d2);
var_dump($d1 > $d2);
var_dump($d1 < $d2);
?>
bool(false)
bool(true)
bool(false)
dev:~# php -v
PHP 5.2.6-1+lenny3 with Suhosin-Pa...
二维码的生成细节及原理 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...一下二维码一共有40个尺寸。官方叫版本Version。Version 1是21 x 21的矩阵，Version 2是 25 x 25的矩阵，Version 3是29的尺寸，每增加一个version，就会增加4的尺寸，公式是：(V-1)*4 + 21（V是版本号） 最高Version 40，(40-1)*4+21 = 177，所以最高是...
String's Maximum length in Java - calling length() method
... that would be returned by the method would be Integer.MAX_VALUE, which is 2^31 - 1 (or approximately 2 billion.)
In terms of lengths and indexing of arrays, (such as char[], which is probably the way the internal data representation is implemented for Strings), Chapter 10: Arrays of The Java Langu...
How can I check which version of Angular I'm using?
...
28 Answers
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Oracle JDBC ojdbc6 Jar as a Maven Dependency
...>
<artifactId>ojdbc6</artifactId>
<version>11.2.0.3</version>
</dependency>
...
<repositories>
<repository>
<id>codelds</id>
<url>https://code.lds.org/nexus/content/groups/main-repo</url>
</repositor...
How to change the output color of echo in Linux
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2435
You can use these ANSI escape codes:
Black 0;30 Dark Gray 1;30
Red 0...
Force LF eol in git repo and working copy
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237
Without a bit of information about what files are in your repository (pure source code, images...
How to convert list of tuples to multiple lists?
...lt-in function zip() will almost do what you want:
>>> zip(*[(1, 2), (3, 4), (5, 6)])
[(1, 3, 5), (2, 4, 6)]
The only difference is that you get tuples instead of lists. You can convert them to lists using
map(list, zip(*[(1, 2), (3, 4), (5, 6)]))
...
Pandas groupby: How to get a union of strings
...s+')
In [5]: df
Out[5]:
A B C
0 1 0.749065 This
1 2 0.301084 is
2 3 0.463468 a
3 4 0.643961 random
4 1 0.866521 string
5 2 0.120737 !
In [6]: df.dtypes
Out[6]:
A int64
B float64
C object
dtype: object
When you apply your own functi...