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When should one use final for method parameters and local variables?
...inal to every class that implement an interface (to be able to create unit tests). Also mark as final all protected/class methods, which are not going to be overridden.
– rmaruszewski
Oct 1 '08 at 10:13
...
How does a Java HashMap handle different objects with the same hash code?
... hashmap immediately knows in which bucket to look, so that it only has to test against what's in that bucket.
Looking at the above mechanism, you can also see what requirements are necessary on the hashCode() and equals() methods of keys:
If two keys are the same (equals() returns true when you ...
What is the most efficient Java Collections library? [closed]
...on't think anyone reading this should listen to either of us. They should test their own use case and see what has the best performance. My comments are based on my team's fairly aggressive performance tests with a variety of libraries. YMMV.
– Alex Miller
How do I delete an exported environment variable?
...
Walkthrough of creating and deleting an environment variable in bash:
Test if the DUALCASE variable exists:
el@apollo:~$ env | grep DUALCASE
el@apollo:~$
It does not, so create the variable and export it:
el@apollo:~$ DUALCASE=1
el@apollo:~$ export DUALCASE
Check if it is there:
el@apol...
Give all the permissions to a user on a DB
...son it doesn't seem to do anything. For exampe, I ran: grant ALL on schema test to userA; but after that userA still doesnt have access to read from the tables on schema test
– Diego
Mar 21 '14 at 9:32
...
Connecting to Azure website via FTP
... need to add a prefix.
Here, my username is "blabla", my website name is "test" ==> my FTP username is thus "test\blabla" (mind the backslash on windows) followed by the password I set on azure portal (no modification required)
here are the references from Azure:
why there are two credential...
Downloading a large file using curl
...
I tested it with a https, works great!!!, Thanks for you help @dynamic.
– Ozal Zarbaliyev
Jan 15 '19 at 13:14
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Pandas: create two new columns in a dataframe with values calculated from a pre-existing column
...pply is generally not much faster than iterating over a Python list. Let's test the performance of a for-loop to do the same thing as above
%%timeit
A1, A2 = [], []
for val in df['a']:
A1.append(val**2)
A2.append(val**3)
df['A1'] = A1
df['A2'] = A2
298 ms ± 7.14 ms per loop (mean ± std....
How to select rows with one or more nulls from a pandas DataFrame without listing columns explicitly
...y verbose, but functional.
import pandas as pd
import numpy as np
# Some test data frame
df = pd.DataFrame({'num_legs': [2, 4, np.nan, 0, np.nan],
'num_wings': [2, 0, np.nan, 0, 9],
'num_specimen_seen': [10, np.nan, 1, 8, np.nan]...
Why is a round-trip conversion via a string not safe for a double?
...t;sPositiveInfinity);
goto lExit;
}
NumberToDouble(&number, &dTest);
if (dTest == value) {
gc.refRetVal = NumberToString(&number, 'G', DOUBLE_PRECISION, gc.numfmt);
goto lExit;
}
DoubleToNumber(value, 17, &number);
DoubleToNumber is pretty simple -- it just calls _ec...