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Omit rows containing specific column of NA
...c("y", "z"))
# x y z
# 2 2 10 33
EDIT: Only return rows with no NAs
If you want to eliminate all rows with at least one NA in any column, just use the complete.cases function straight up:
DF[complete.cases(DF), ]
# x y z
# 2 2 10 33
Or if completeFun is already ingrained in your workfl...
Inline code in org-mode
...d font and export it verbatim (which means it is not processed for org-specific syntax):
This is =verbatim text= or ~code~.
You'll find all information about org-mode markup elements in the relevant section of the manual.
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How to add column if not exists on PostgreSQL?
...when x column doesn't exist ? I found only solution here how to check if column exists.
11 Answers
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Best practice using NSLocalizedString
...he existing string files as closely as possible to avoid having too big a diff when updating them.
Naming your strings
If you use NSLocalizedString as advertised:
NSLocalizedString(@"Cancel or continue?", @"Cancel notice message when a download takes too long to proceed");
You may end up defini...
Does the Java &= operator apply & or &&?
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From the Java Language Specification - 15.26.2 Compound Assignment Operators.
A compound assignment expression of the form E1 op= E2 is equivalent to E1 = (T)((E1) op (E2)), where T is the type of E1, except that E1 is evaluated only once.
So a &...
Ruby function to remove all white spaces?
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If you want to remove only leading and trailing whitespace (like PHP's trim) you can use .strip, but if you want to remove all whitespace, you can use .gsub(/\s+/, "") instead .
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How to create a file with a given size in Linux?
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dd if=/dev/zero of=upload_test bs=file_size count=1
Where file_size is the size of your test file in bytes
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How to keep one variable constant with other one changing with row in excel
...n dragging. $B1 (B will be kept constant and the 1 will count up) will be different to $B$1 (both B and 1 will remain constant)
– Jonno_FTW
Jan 28 '10 at 17:40
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Index on multiple columns in Ruby on Rails
...insofar as you use its columns in sequence starting at the beginning. i.e. if you index on [:user_id, :article_id], you can perform a fast query on user_id or user_id AND article_id, but NOT on article_id.
Your migration add_index line should look something like this:
add_index :user_views, [:us...
MySQL join with where clause
... or the where is equivalent. However, with an outer join, they are vastly different.
As a join condition, you specify the rowset that you will be joining to the table. This means that it evaluates user_id = 1 first, and takes the subset of user_category_subscriptions with a user_id of 1 to join to ...