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Apply a function to every row of a matrix or a data frame
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182
You simply use the apply() function:
R> M <- matrix(1:6, nrow=3, byrow=TRUE)
R> M
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Replace all 0 values to NA
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Replacing all zeroes to NA:
df[df == 0] <- NA
Explanation
1. It is not NULL what you should want to replace zeroes with. As it says in ?'NULL',
NULL represents the null object in R
which is unique and, I guess, can be seen as the most uninformative and empty object.1 Then it b...
Pandas index column title or name
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In [8]: df.index.name = 'foo'
In [9]: df.index.name
Out[9]: 'foo'
In [10]: df
Out[10]:
Column 1
foo
Apples 1
Oranges 2
Puppies 3
Ducks 4
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Type-juggling and (strict) greater/lesser-than comparisons in PHP
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edited May 23 '17 at 11:47
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answered Apr 4 '13 at 14:10
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Regex to validate date format dd/mm/yyyy
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I modified it to take dd/mm/yyyy, dd-mm-yyyy or dd.mm.yyyy.
^(?:(?:31(\/|-|\.)(?:0?[13578]|1[02]))\1|(?:(?:29|30)(\/|-|\.)(?:0?[13-9]|1[0-2])\2))(?:(?:1[6-9]|[2-9]\d)?\d{2})$|^(?:29(\/|-|\.)0?2\3(?:(?:(?:1[6-9]|[2-9]\d)?(?:0[48]|[2468][048]|[13579][26])|(?:(?:16|[2468][048]|[3579][26])00))))$...
How can I use “:” as an AWK field separator?
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"-F" is a command line argument, not AWK syntax. Try:
echo "1: " | awk -F ":" '/1/ {print $1}'
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Why does direction of index matter in MongoDB?
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114
MongoDB concatenates the compound key in some way and uses it as the key in a BTree.
When fin...
SQL Logic Operator Precedence: And and Or
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And has precedence over Or, so, even if a <=> a1 Or a2
Where a And b
is not the same as
Where a1 Or a2 And b,
because that would be Executed as
Where a1 Or (a2 And b)
and what you want, to make them the same, is the following (using parentheses to override rule...
Find the most frequent number in a numpy vector
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12 Answers
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Regular expression to match numbers with or without commas and decimals in text
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10 Answers
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