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Should I use a data.frame or a matrix?
...e the choice.
Also:
Matrices are more memory efficient:
m = matrix(1:4, 2, 2)
d = as.data.frame(m)
object.size(m)
# 216 bytes
object.size(d)
# 792 bytes
Matrices are a necessity if you plan to do any linear algebra-type of operations.
Data frames are more convenient if you frequently refer to ...
How to delete an element from an array in C#
...
342
If you want to remove all instances of 4 without needing to know the index:
LINQ: (.NET Framewo...
PostgreSQL - max number of parameters in “IN” clause?
...
Jordan S. JonesJordan S. Jones
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add a ...
How to insert a character in a string at a certain position?
...igit value. I want to display it as a String with a decimal point (.) at 2 digits from the end of int . I wanted to use a float but was suggested to use String for a better display output (instead of 1234.5 will be 1234.50 ). Therefore, I need a function that will take an int as paramete...
Checking if a string can be converted to float in Python
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edited Nov 11 '19 at 12:29
Richard Simões
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a...
Ruby: What is the easiest way to remove the first element from an array?
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291
"pop"ing the first element of an Array is called "shift" ("unshift"
being the operation of add...
Validate phone number with JavaScript
...ectly. It validates that the phone number is in one of these formats:
(123) 456-7890 or 123-456-7890
26 Answers
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How to calculate “time ago” in Java?
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edited Nov 28 '16 at 8:15
jdersen
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answered Oct 4 '10...
Clojure: cons (seq) vs. conj (list)
...guments to insert into a collection, while cons takes just one:
(conj '(1 2 3) 4 5 6)
; => (6 5 4 1 2 3)
(cons 4 5 6 '(1 2 3))
; => IllegalArgumentException due to wrong arity
Another difference is in the class of the return value:
(class (conj '(1 2 3) 4))
; => clojure.lang.Persistent...