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Compile time string hashing
...the code snippet:
// CRC32 Table (zlib polynomial)
static constexpr uint32_t crc_table[256] = {
0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d0...
Selecting multiple columns in a pandas dataframe
...ou can just return a view of only those columns by passing a list into the __getitem__ syntax (the []'s).
df1 = df[['a', 'b']]
Alternatively, if it matters to index them numerically and not by their name (say your code should automatically do this without knowing the names of the first two columns)...
Elegant way to invert a map in Scala
...
Assuming values are unique, this works:
(Map() ++ origMap.map(_.swap))
On Scala 2.8, however, it's easier:
origMap.map(_.swap)
Being able to do that is part of the reason why Scala 2.8 has a new collection library.
...
In practice, what are the main uses for the new “yield from” syntax in Python 3.3?
... etc."""
for i in range(4):
yield '<< %s' % i
def reader_wrapper(g):
# Manually iterate over data produced by reader
for v in g:
yield v
wrap = reader_wrapper(reader())
for i in wrap:
print(i)
# Result
<< 0
<< 1
<< 2
<< 3
Instead of ...
How do you get a list of the names of all files present in a directory in Node.js?
...? I want to ignore directories starting with .git
– j_d
May 3 '16 at 12:14
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show 3 more comments
...
How do you format an unsigned long long int using printf?
...want to try using the inttypes.h library that gives you types such as
int32_t, int64_t, uint64_t etc.
You can then use its macros such as:
uint64_t x;
uint32_t y;
printf("x: %"PRId64", y: %"PRId32"\n", x, y);
This is "guaranteed" to not give you the same trouble as long, unsigned long long etc, ...
Weak and strong property setter attributes in Objective-C
...n release autorelease etc... Instead you use strong weak for properties or __strong
__weak
for variables (defaults to __strong). Strong is the equivalent to retain, however ARC will manage the release for you.
The only time you would want to use weak, is if you wanted to avoid retain cycles (e.g...
How to check if all elements of a list matches a condition?
... items = [[1, 2, 0], [1, 2, 0], [1, 2, 0]]
>>> all(flag == 0 for (_, _, flag) in items)
True
>>> items = [[1, 2, 0], [1, 2, 1], [1, 2, 0]]
>>> all(flag == 0 for (_, _, flag) in items)
False
Note that all(flag == 0 for (_, _, flag) in items) is directly equivalent to all(...
How to list the contents of a package using YUM?
... Why install a new package when you can use rpm -ql $PACKAGE_NAME?
– isapir
Apr 8 '19 at 17:42
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show 1 more comment
...
What is the difference between C# and .NET?
...ment 0x00000200
.stackreserve 0x00100000
.subsystem 0x0003 // WINDOWS_CUI
.corflags 0x00000001 // ILONLY
// Image base: 0x05DB0000
// =============== CLASS MEMBERS DECLARATION ===================
.class public auto ansi beforefieldinit Example.Class1
extends [mscorlib]System.Objec...