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Determine the data types of a data frame's columns
...integer" "logical" "factor"
Using str() gets you that information plus extra goodies (such as the levels of your factors and the first few values of each variable):
str(my.data)
'data.frame': 5 obs. of 4 variables:
$ y : num 1.03 1.599 -0.818 0.872 -2.682
$ x1: int 1 2 3 4 5
$ x2: logi T...
Bash script to receive and repass quoted parameters
...# $4= "ddd ddd"
"$*" - quoted-dollar-star smashes the args into a single string (~1% of the time you actually want this behavior, eg in a conditional: if [[ -z "$*" ]]; then ...):
./quoted-dollar-star.sh aaa '' "'cc cc'" '"ddd ddd"'
# $1= aaa 'cc cc' "ddd ddd"
# $2=
...
Return 0 if field is null in MySQL
...) returns expr1; otherwise it returns expr2. IFNULL() returns a numeric or string value, depending on the context in which it is used.
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How does IPython's magic %paste work?
...est_mode which allows you to copy paste example and test snippets from doc strings. This is also useful to execute interactive python session output that you could find in documentation and online forums, without having to first strip out the prompt strings.
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bash assign default value
...riable without needing to reassign
# colons suppress attempting to run the string
unset EGGS
: ${EGGS=spam}
echo 1 $EGGS # 1 spam
unset EGGS
: ${EGGS:=spam}
echo 2 $EGGS # 2 spam
EGGS=
: ${EGGS=spam}
echo 3 $EGGS # 3 (set, but blank -> leaves alone)
EGGS=
: ${EGGS:=spam}
echo ...
How to drop rows of Pandas DataFrame whose value in a certain column is NaN
...ilippSchwarz This error occurs if the column (EPS in the example) contains strings or other types that cannot be digested by np.isfinite(). I recommend to use pandas.notnull() that will handle this more generously.
– normanius
Apr 5 '18 at 10:02
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What is the difference between .*? and .* regular expressions?
I'm trying to split up a string into two parts using regex. The string is formatted as follows:
3 Answers
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What is JavaScript garbage collection?
...called a "scavenger". A scavenger
may refer to a number, an object, a
string, whatever. We maintain a list
of scavengers -- variables are moved
on to the scav list when they come
into scope and off the scav list when
they go out of scope.
Every now and then the garbage
collector ru...
Java 8 Iterable.forEach() vs foreach loop
...c.join(mSession, join));
is not intended as a shortcut for writing
for (String join : joins) {
mIrc.join(mSession, join);
}
and should certainly not be used in this way. Instead it is intended as a shortcut (although it is not exactly the same) for writing
joins.forEach(new Consumer<T&g...
How to use OpenSSL to encrypt/decrypt files?
...bove!
-K key
The actual key to use: this must be represented as a string
comprised only of hex digits. If only the key is specified, the
IV must additionally be specified using the -iv option. When
both a key and a password are specified, the key given with the
-K option wi...