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Select random lines from a file
In a Bash script, I want to pick out N random lines from input file and output to another file.
4 Answers
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Algorithm to return all combinations of k elements from n
I want to write a function that takes an array of letters as an argument and a number of those letters to select.
71 Answe...
CSV file written with Python has blank lines between each row
This code reads thefile.csv , makes changes, and writes results to thefile_subset1 .
9 Answers
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Fastest way to extract frames using ffmpeg?
...about 20 times faster. We use fast seeking to go to the desired time index and extract a frame, then call ffmpeg several times for every time index. Note that -accurate_seek is the default
, and make sure you add -ss before the input video -i option.
Note that it's better to use -filter:v -fps=fps=...
Which characters need to be escaped when using Bash?
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There are two easy and safe rules which work not only in sh but also bash.
1. Put the whole string in single quotes
This works for all chars except single quote itself. To escape the single quote, close the quoting before it, insert the singl...
PHP - how to create a newline character?
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Only double quoted strings interpret the escape sequences \r and \n as '0x0D' and '0x0A' respectively, so you want:
"\r\n"
Single quoted strings, on the other hand, only know the escape sequences \\ and \'.
So unless you concatenate the single quoted string with a line break genera...
How can I pad a value with leading zeros?
...o readers!
As commenters have pointed out, this solution is "clever", and as
clever solutions often are, it's memory intensive and relatively
slow. If performance is a concern for you, don't use this solution!
Potentially outdated: ECMAScript 2017 includes String.prototype.padStart and...
How to iterate over associative arrays in Bash
...sociative array in a Bash script, I need to iterate over it to get the key and value.
4 Answers
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When to use a linked list over an array/array list?
I use a lot of lists and arrays but I have yet to come across a scenario in which the array list couldn't be used just as easily as, if not easier than, the linked list. I was hoping someone could give me some examples of when the linked list is notably better.
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How to remove leading and trailing zeros in a string? Python
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What about a basic
your_string.strip("0")
to remove both trailing and leading zeros ? If you're only interested in removing trailing zeros, use .rstrip instead (and .lstrip for only the leading ones).
[More info in the doc.]
You could use some list comprehension to get the sequences you w...