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Pandas - Get first row value of a given column
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There is a difference between df_test['Btime'].iloc[0] (recommended) and df_test.iloc[0]['Btime']:
DataFrames store data in column-based blocks (where each block has a single
dtype). If you select by column first, a view can be returned (which is
quicker than returning a copy) and the origina...
Python assigning multiple variables to same value? list behavior
...he behavior, I expect to reassign the values list separately, I mean b[0] and c[0] equal 0 as before.
9 Answers
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What is the “-->” operator in C++?
After reading Hidden Features and Dark Corners of C++/STL on comp.lang.c++.moderated , I was completely surprised that the following snippet compiled and worked in both Visual Studio 2008 and G++ 4.4.
...
How can I eliminate slow resolving/loading of localhost/virtualhost (a 2-3 second lag) on Mac OS X L
Since setting up my development environments on Mac OS X Lion (brand new macbook air purchased in January 2012), I have noticed that resolving to a virtual host is very slow (around 3 seconds) the first time but after that is fast as long as I continue loading it regularly.
...
Why is January month 0 in Java Calendar?
...a date/time API. Listing what's wrong with it would take a very long time (and I'm sure I don't know half of the problems). Admittedly working with dates and times is tricky, but aaargh anyway.
Do yourself a favour and use Joda Time instead, or possibly JSR-310.
EDIT: As for the reasons why - as n...
How is a CRC32 checksum calculated?
... + x8 + x7 + x5 + x4 + x2 + x + 1
Wikipedia
CRC calculation
Or in hex and binary:
0x 01 04 C1 1D B7
1 0000 0100 1100 0001 0001 1101 1011 0111
The highest term (x32) is usually not explicitly written, so it can instead be represented in hex just as
0x 04 C1 1D B7
Feel free to count...
Obfuscated C Code Contest 2006. Please explain sykes2.c
...char(32 | (b & 1));
}
}
Now, note that a[b] is the same as b[a], and apply the -~ == 1+ change again:
main(int i) {
if(i != 448)
main(i+1);
i--;
if(i % 64 == 0) {
putchar('\n');
} else {
char a = (">'txiZ^(~z?"-48)[(__TIME__-i/8%8)[7]] + 1;
...
Why are these numbers not equal?
...umbers can be represented exactly in IEEE floating point arithmetic (the standard that almost all computers use to represent decimal numbers and do math with them), you will not always get what you expected. This is especially true because some values which are simple, finite decimals (such as 0.1 a...
How to style dt and dd so they are on the same line?
... <dd>Mercury (0.4 AU from the Sun) is the closest planet to the Sun and the smallest planet.</dd>
<dt>Venus</dt>
<dd>Venus (0.7 AU) is close in size to Earth, (0.815 Earth masses) and like Earth, has a thick silicate mantle around an iron core.</dd>
<...
Why do indexes in XPath start with 1 and not 0?
Some colleagues and I were comparing past languages we had programmed in and were talking about our experience with VBScript with its odd features such as 1-based index instead of 0-based indexes like almost every other language has, the reasoning being that it was a language for users (e.g....