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Comparing two dataframes and getting the differences
... behaviour for pd.concat(), here's the docs pandas.pydata.org/pandas-docs/stable/merging.html
– Thanos
Apr 17 '16 at 18:35
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What does the KEY keyword mean?
In this MySQL table definition:
2 Answers
2
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GetHashCode Guidelines in C#
... It also doesn't tell the whole story.
The point being made is that for mutable types, you cannot base the hash code on the mutable data because two equal objects must return the same hash code and the hash code has to be valid for the lifetime of the object. If the hash code changes, you end up wi...
How to change the type of a field?
...big deal no matter how you do it. If you were using SQL and this was a big table you would probably have to take some down time.
– Gates VP
Jun 28 '16 at 18:16
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Java: difference between strong/soft/weak/phantom reference
...ap
Restaurant area/space - Heap space
New Customer - New object that wants table in restaurant
Now if you are a strong customer (analogous to strong reference), then even if a new customer comes in the restaurant or what so ever happnes, you will never leave your table (the memory area on heap). Th...
Python circular importing?
...depends on whether the file you are importing already exists in the module table. If it does, Python uses whatever is currently in the symbol table. If not, Python begins reading the module file, compiling/executing/importing whatever it finds there. Symbols referenced at compile time are found or...
How to read data when some numbers contain commas as thousand separator?
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You can have read.table or read.csv do this conversion for you semi-automatically. First create a new class definition, then create a conversion function and set it as an "as" method using the setAs function like so:
setClass("num.with.commas...
Are negative array indexes allowed in C?
...want to use negative indexes, I have used them in two contexts:
Having a table of combinatorial numbers that tells you comb[1][-1] = 0; you can always check indexes before accessing the table, but this way the code looks cleaner and executes faster.
Putting a centinel at the beginning of a table. ...
How do I find an element that contains specific text in Selenium Webdriver (Python)?
...substitutes a source character to its desired form, by using a translation table.
Constructing a table of all upper case characters will effectively transform the node's text to its lower() form - allowing case-insensitive matching (here's just the prerogative):
[
contains(
translate(text(),...
best practice to generate random token for forgot password
...rch in about a week's time for a low-budget attacker:
mt_rand() is predictable (and only adds up to 31 bits of entropy)
uniqid() only adds up to 29 bits of entropy
md5() doesn't add entropy, it just mixes it deterministically
Since a 56-bit DES key can be brute-forced in about 24 hours, and an a...