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How to drop columns by name in a data frame
..."z","u"))]
x y
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Or, much simpler, use the select argument of the subset function : you can then use the - operator directly on a vector of column names, and you can even omit the quotes around the names !
R> subset(df, select=-c(z,u))
x y
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2 2 3
3 3 4
4 4 ...
How can I select the first day of a month in SQL?
I just need to select the first day of the month of a given datetime variable.
30 Answers
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SQL: capitalize first letter only [duplicate]
...t only for displaying and do not need the actual data in table to change:
SELECT UPPER(LEFT(word,1))+LOWER(SUBSTRING(word,2,LEN(word))) FROM [yourtable]
Hope this helps.
EDIT: I realised about the '-' so here is my attempt to solve this problem in a function.
CREATE FUNCTION [dbo].[CapitalizeFi...
Android ViewPager with bottom dots
...droid:layout_height="wrap_content"
app:tabBackground="@drawable/tab_selector"
app:tabGravity="center"
app:tabIndicatorHeight="0dp"/>
</RelativeLayout>
Hook up your UI elements inactivity or fragment as follows:
Java Code:
mImageViewPager = (ViewPager) findViewById(R.id...
Get names of all files from a folder with Ruby
...ng subdirectories and ".", ".." dotted folders:
Dir.entries("your/folder").select { |f| File.file? File.join("your/folder", f) }
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PostgreSQL - fetch the row which has the Max value for a column
...sted index lookup into lives - on my machine
-- the latter query plan was selected given my memory settings and
-- histogram
SELECT
l1.*
FROM
lives AS l1
INNER JOIN (
SELECT
usr_id,
MAX(time_stamp) AS time_stamp_max
FROM
lives
GROUP BY
usr_id
) AS l2
...
How can I select rows with most recent timestamp for each key value?
...r data. Each row has a sensor id, a timestamp, and other fields. I want to select a single row with latest timestamp for each sensor, including some of the other fields.
...
How to increase font size in the Xcode editor?
...)
Go to XCode > Preferences > Fonts & Color
From the 'Theme' box select the theme you want to modify (or select the theme you want to modify and click the "+" button at the bottom of the theme list to clone it first for backup, for there is no undo option)
In the source editor box there is...
XPath to select multiple tags
...l-name()='e']
is both too-long and incorrect. This XPath expression will select nodes like:
OhMy:c
NotWanted:d
QuiteDifferent:e
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Simple Vim commands you wish you'd known earlier [closed]
...-search extends the functionality of * to match the whole text of a visual selection which makes it easy to search & replace the selected text, e.g. v3e (visually select 3 words) * (search) and :%s//replacement/g (replace all occurences with "replacement"). I use this so often that I have a mapp...