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How to drop columns by name in a data frame
I have a large data set and I would like to read specific columns or drop all the others.
11 Answers
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Should a “static final Logger” be declared in UPPER-CASE?
...aph 3.3 Field Naming
Names of fields being used as constants should be all upper-case, with underscores separating words. The following are considered to be constants:
All static final primitive types (Remember that all interface fields are inherently static final).
All static final ob...
Why can't the C# constructor infer type?
...type inference?
No. When you have
new Foo(bar)
then we could identify all types called Foo in scope regardless of generic arity, and then do overload resolution on each using a modified method type inference algorithm. We'd then have to create a 'betterness' algorithm that determines which of t...
Is there a simple way to delete a list element by value?
...('b')
>>> print(a)
['a', 'c', 'd']
Mind that it does not remove all occurrences of your element. Use a list comprehension for that.
>>> a = [10, 20, 30, 40, 20, 30, 40, 20, 70, 20]
>>> a = [x for x in a if x != 20]
>>> print(a)
[10, 30, 40, 30, 40, 70]
...
Pairs from single list
...e=2):
it = iter(t)
return izip(*[it]*size)
When you want to pair all elements you obviously might need a fillvalue:
from itertools import izip_longest
def blockwise(t, size=2, fillvalue=None):
it = iter(t)
return izip_longest(*[it]*size, fillvalue=fillvalue)
...
Why is my program slow when looping over exactly 8192 elements?
...much slower than transposing a matrix of 513x513?
Matrix multiplication: Small difference in matrix size, large difference in timings
But that's only because there's one other problem with the code.
Starting from the original loop:
for(i=1;i<SIZE-1;i++)
for(j=1;j<SIZE-1;j++) {
...
Windows batch files: .bat vs .cmd?
...g that my code will never need to run on anything older than NT, does it really matter which way I name my batch files, or is there some gotcha awaiting me by using the wrong suffix?
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How to define a function in ghci across multiple lines?
...
For guards (like your example), you can just put them all on one line and it works (guards do not care about spacing)
let abs n | n >= 0 = n | otherwise = -n
If you wanted to write your function with multiple definitions that pattern match on the arguments, like this:
fac...
Difference between break and continue statement
...necessary to exit a loop before the loop has finished fully iterating over all the step values. For example, looping over a list of numbers until you find a number that satisfies a certain condition. Or looping over a stream of characters from a file until a certain character is read.
In the follow...
time.sleep — sleeps thread or process?
...look in Modules/timemodule.c in the Python source, you'll see that in the call to floatsleep(), the substantive part of the sleep operation is wrapped in a Py_BEGIN_ALLOW_THREADS and Py_END_ALLOW_THREADS block, allowing other threads to continue to execute while the current one sleeps. You can also...