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Closed 10 years ago.
In my params hash, I receive a value for :limit. I need to assign this value to a variable limit, but not exceed 50, and if the value for :limit is not given, default to 50.
First, I did this:
limit = [params[:limit], 50].min
This will make it maximum of 50, but won't work: If nothing is given for :limit, then this will make limit 0.
Next, I did this:
limit = [params[:limit] || 50, 50].min
This works, but I am wondering if this is efficient or if there's a better way to do this.
try
limit = (params[:limit] && params[:limit] < 50) ? params[:limit] : 50
Your solution it's quite easy to read but rather inefficient because you're creating an array and invoking the min method every time and it is an overkill.
A maybe less readable and more verbose but more easy on the machine approach could be:
if params[:limit] && params[:limit] < 50
params[:limit]
else
50
end
Related
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Closed 10 years ago.
So my problem is I try to compare two links from tumblr and choose that link which has higher number in this case is just choose _1280 over _500.
http://25.media.tumblr.com/393e9f295c4cac3af0a4b6d3a64c434d/tumblr_mi9e85iFwA1qavye5o1_500.jpg
http://25.media.tumblr.com/393e9f295c4cac3af0a4b6d3a64c434d/tumblr_mi9e85iFwA1qavye5o1_1280.jpg
I know how to get image links from tumblr but I'm too stupid to make, a code for this. I don't even know how to start... And this is just my beginning of trying do something in bash (cygwin).
I will appreciate any help :)
Here are some string manipulation functions to get you started.
bash:~$ var1=http://25.media.tumblr.com/393e9f295c4cac3af0a4b6d3a64c434d/tumblr_mi9e85iFwA1qavye5o1_500.jpg
bash:~$ var2=${var1##*_}
This gives you the part of the string after the last underscore
bash:~$ echo $var2
should output 500.jpg
bash:~$ var3=${var2%.*}
This gives you the part before the dot
bash:~$ echo $var3
should output 500
Then you can compare the numbers.
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Closed 10 years ago.
I don't know why I have this strange error when using Octave on Windows 7 64 bit :
when I use ones(100:100) to declare a matrix 100x100. No problem. But when I use : ones(10:100) I will have error :
memory exhausted or requested size too large
And if I use ones(10:15) I must wait for long time (about 30 seconds) to have answer.
Please explain for me this error.
Thanks :)
Your syntax is wrong. To create an m x n matrix it should be:
ones(m,n)
e.g.
ones(100,100)
or
ones(10,15)
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Closed 10 years ago.
I have a basic math question. I am trying to get a percentage from a range of numbers and the algorithm is troubling me.
Say I have a range of -5 to +5 and I want to know what percentage is in between given a value. I know that -5 would be equivalent to 0% and 5 would be 100%, with 0 being 50%.
I tried to add 5 to bring up the scale, but it just feels like a hack. I would like it to feel dynamic so that I can give it any range and successfully work.
Ex.
percent = (5 + value) * 100 / 10
How do I figure out what value should be the a general case?
range = top_value - bottom_value
percent = (value - bottom_value) / range
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Closed 10 years ago.
I want to do this.
Create 10000 files, (filename can be just combination of time and random number).
File size should be 4k.
And I want to time this. say how many seconds it will take.
How can I do this on bash?
Thank you.
time for x in {1..10000}; do
dd if=/dev/zero ibs=4k count=1 of=$x.txt 2>/dev/null
done
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Closed 10 years ago.
Can you compare multiple values in a single if statement in Ruby? If so, how? I know in other languages, you would just use a double ampersand (&&), but I have never seen any example or documentation about it, even in the official ruby documentation! Thanks for all the help in advance.
Yes, you can use the && operator
if a == 1 && b == 2
# do things
end
It IS in the documentation.
http://www.ruby-doc.org/docs/ProgrammingRuby/html/tut_expressions.html#UG