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Combine two or more columns in a dataframe into a new column with a new name
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Use paste.
df$x <- paste(df$n,df$s)
df
# n s b x
# 1 2 aa TRUE 2 aa
# 2 3 bb FALSE 3 bb
# 3 5 cc TRUE 5 cc
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How to get current formatted date dd/mm/yyyy in Javascript and append it to an input [duplicate]
I would like to add a current date to a hidden HTML tag so that it can be sent to the server:
7 Answers
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python capitalize first letter only
I am aware .capitalize() capitalizes the first letter of a string but what if the first character is a integer?
8 Answers
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When NOT to call super() method when overriding?
...ustom class, I extend its native class. Then when I want to override the base method, I always call super() method, just like I always do in onCreate , onStop , etc.
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Call a function from another file?
...te from file import function, and then call the function using function(a, b). The reason why this may not work, is because file is one of Python's core modules, so I suggest you change the name of your file.
Note that if you're trying to import functions from a.py to a file called b.py, you will n...
XPath to select multiple tags
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One correct answer is:
/a/b/*[self::c or self::d or self::e]
Do note that this
a/b/*[local-name()='c' or local-name()='d' or local-name()='e']
is both too-long and incorrect. This XPath expression will select nodes like:
OhMy:c
NotWanted:d
Qu...
Adding a column to a data.frame
I have the data.frame below. I want to add a column that classifies my data according to column 1 ( h_no ) in that way that the first series of h_no 1,2,3,4 is class 1, the second series of h_no (1 to 7) is class 2 etc. such as indicated in the last column.
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Why does PHP 5.2+ disallow abstract static class methods?
After enabling strict warnings in PHP 5.2, I saw a load of strict standards warnings from a project that was originally written without strict warnings:
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Creating a “logical exclusive or” operator in Java
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Java does have a logical XOR operator, it is ^ (as in a ^ b).
Apart from that, you can't define new operators in Java.
Edit: Here's an example:
public static void main(String[] args) {
boolean[] all = { false, true };
for (boolean a : all) {
for (boolean b: all) ...
How to count the frequency of the elements in an unordered list?
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Note: You should sort the list before using groupby.
You can use groupby from itertools package if the list is an ordered list.
a = [1,1,1,1,2,2,2,2,3,3,4,5,5]
from itertools import groupby
[len(list(group)) for key, group in groupby(a)]
Output:
[4, 4...