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Select first 4 rows of a data.frame in R
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You can use the "index" answer pointed out elsewhere. In this situation I normally use the slice function in dplyr. (Behavior depends on the grouping.)
– Eduardo Leoni
May 28 '18 at 21:16
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Concatenate two slices in Go
I'm trying to combine the slice [1, 2] and the slice [3, 4] . How can I do this in Go?
7 Answers
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Numpy where function multiple conditions
...ts. I want to select dists which are between two values. I wrote the following line of code to do that:
8 Answers
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Bash empty array expansion with `set -u`
I'm writing a bash script which has set -u , and I have a problem with empty array expansion: bash appears to treat an empty array as an unset variable during expansion:
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Numpy array dimensions
I'm currently trying to learn Numpy and Python. Given the following array:
8 Answers
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Print all but the first three columns
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A solution that does not add extra leading or trailing whitespace:
awk '{ for(i=4; i<NF; i++) printf "%s",$i OFS; if(NF) printf "%s",$NF; printf ORS}'
### Example ###
$ echo '1 2 3 4 5 6 7' |
awk '{for(i=4;i<NF;i++)printf"%s",$i OFS;if(NF)printf"%s",$NF;...
Remove duplicate elements from array in Ruby
I have a Ruby array which contains duplicate elements.
7 Answers
7
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How do I convert a string to a number in PHP?
...rt these types of values, '3' , '2.34' , '0.234343' , etc. to a number. In JavaScript we can use Number() , but is there any similar method available in PHP?
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How to parse the AndroidManifest.xml file inside an .apk package
This file appears to be in a binary XML format. What is this format and how can it be parsed programmatically (as opposed to using the aapt dump tool in the SDK)?
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how to concatenate two dictionaries to create a new one in Python? [duplicate]
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Slowest and doesn't work in Python3: concatenate the items and call dict on the resulting list:
$ python -mtimeit -s'd1={1:2,3:4}; d2={5:6,7:9}; d3={10:8,13:22}' \
'd4 = dict(d1.items() + d2.items() + d3.items())'
100000 loops, best of 3: 4.93 usec...