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Combine two or more columns in a dataframe into a new column with a new name
...x <- paste(df$n,df$s)
df
# n s b x
# 1 2 aa TRUE 2 aa
# 2 3 bb FALSE 3 bb
# 3 5 cc TRUE 5 cc
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内存管理内幕：动态分配的选择、折衷和实现 - C/C++ - 清泛网 - 专注C/C++及内核技术
...理：
void *malloc(long numbytes)：该函数负责分配 numbytes 大小的内存，并返回指向第一个字节的指针。
void free(void *firstbyte)：如果给定一个由先前的 malloc 返回的指针，那么该函数会将分配的空间归还给进程的“空闲空间”。
mal...
What is the significance of ProjectTypeGuids tag in the visual studio project file
...1D3-BF4B-00C04F79EFBC} is the GUID for C# project
{60dc8134-eba5-43b8-bcc9-bb4bc16c2548} is for project in WPF flavor package
So your ProjectTypeGuids is for a WPF C# project.
You could see the meaning of the different GUID in the register :
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\VisualStudio\10...
How to save username and password with Mercurial?
...make an auth section in your .hgrc or Mercurial.ini file, like so:
[auth]
bb.prefix = https://bitbucket.org/repo/path
bb.username = foo
bb.password = foo_passwd
The ‘bb’ part is an arbitrary identifier and is used to match prefix with username and password - handy for managing different usern...
How to check whether a pandas DataFrame is empty?
...but still retains n columns
In [4]: df2 = pd.DataFrame({'AA' : [1, 2, 3], 'BB' : [11, 22, 33]})
df2
Out[4]: AA BB
0 1 11
1 2 22
2 3 33
In [5]: df2 = df2[df2['AA'] == 5]
df2
Out[5]: Empty DataFrame
Columns: [AA, BB]
Index: []
In [...
CSS – why doesn’t percentage height work? [duplicate]
...e="width: 100px; background-color: orange">
<div id="bb" style="width: 100px; height: 50%; background-color: blue"></div>
</div>
In this example, the containing block of #aa is #a, and so on for #b and #bb. So far, so good.
The next sentence of the spec ...
Bare asterisk in function arguments?
...ce you haven't named it anything, its only effect is probably to quietly gobble up all the remaining positional arguments, in order to force the remaining arguments to be keyword-only.
– Stephen
Apr 25 '18 at 17:19
...
How do I use Java to read from a file that is actively being written to?
... Your link to Tailer is broken.
– Stealth Rabbi
Jul 22 '16 at 17:06
2
@StealthRabbi The ...
Any way to properly pretty-print ordered dictionaries?
... ])),
('b', OrderedDict([
('b1', OrderedDict([
('bb1',1),
('bb2',4.5)])),
('b2',4.5)
])),
])
I do
def dict_or_OrdDict_to_formatted_str(OD, mode='dict', s="", indent=' '*4, level=0):
def is_number(s):
try:
float(s)
...
How to split a string, but also keep the delimiters?
...t;=,)|(?=,)"));
// "[1][,][234][,][567][,][890]"
dump(":a:bb::c:".split("(?=:)|(?<=:)"));
// "[][:][a][:][bb][:][:][c][:]"
dump(":a:bb::c:".split("(?=(?!^):)|(?<=:)"));
// "[:][a][:][bb][:][:][c][:]"
dump(":::a::::b b::c:".split("(?=(?!^):)(?&l...