Just some random dates
The new Dáil will sit on March 9th when votes will be taken on a new Taoiseach.
That sentence was applicable in two separate years, 1932, and 2011.
The new Dáil will sit on March 9th when votes will be taken on a new Taoiseach.
That sentence was applicable in two separate years, 1932, and 2011.
So you want to split a file in two (even or uneven).
The command `split` will do this for you.
Should you wish to use it, it defaults to 1000 lines for large files as the point to split a file.
However, if you want to split a file which has 701 lines and you want to split it at the 502 line, then you would simply do this:
split -l502 SplitMeFileName
and the file would be split in two pieces.
They would be called xaa and xab unless you state what the file should be called.
Nine Digits turned into something with two decimal places, and with commas for thousands.
sed ‘s/./\.&/8′ FileWithNumbersToBeParsed | sed ‘s/./\,&/5′ | sed ‘s/./\,&/2′ >foo
or how to turn
123456789
into
1,234,567.89
The .& or ,& puts the comma or decimal point in the correct location, start on the right hand side or you will have more fun than you need.
(try it to find out )
This is how you insert a character into a string.
You want to put a leading space into every line in a file?
sed ‘s/./\ &/’ FileName
What might not be obvious from this line is the space before the &.
And some Awkdate | awk '{print $2 " " $6}' how to print specific strings from some random input. date Wed Apr 6 23:15:10 IST 2011 we get the output Apr 2011 That's all folks.
Without going into the why’s I thought I would publish these few lines to amuse some of the people I know get the odd ping from this blog.
There are a long list of numbers in Subt, I want to get a running total (that is the awk bit).
Not only that but then I padded all the lines using printf so that if they were not nine digits long they were padded in front of them.
cat Subt | awk ‘{s+=$1} {print s}’ | xargs printf “%09d\n” > RunningT
Had I wanted a total then this would have worked:
cat Subt | awk ‘{s+=$1} END {print s}’ > FileContainingTotal
How to select a variable from a long list using a simple gui command.
(the file RunningT is several hundred lines long)
kdialog –menu “select your amount” $(cat RunningT) –geometry 700×400
(no I don’t know how to do that with zenity, or even if it can be done {yay for kludge})
Now if that is not enough fun, get a giggle at this one:
cat RunningT | awk ‘{ print FNR “\t” $0 }’ > foo
Yes folks we can add an line number to the file RunningT and create a new file called foo for no good reason.
The ways you can do this are many.
Cut lines off top of file three of them and park them somewhere.
head -n3 SourceForComputation > HeaderPrep
tail does the other end of the file
One of the problems I had with this little adventure was to insure that specific content was always placed in the the file but it could be scattered around the place (I would be splitting the file later)
You can use sort, however that might put your data in a strange place.
So grep for that special_data to extract it and redirect it to a holding file.
Fine how do you remove specific data from a file so you don’t duplicate your processing of it?
grep -Ev What\ I\ Want\ Removed File-to-remove-data-from > Result
(woops I had first published this as Ve)
and we get a Result
Anyway that was just a few notes on the fun parts of processing data using bash and awk
Went back to improv classes for the first time in a long time last night. Great craic.
It is a little like riding a bike, you remember when you get back to it how it went.
Enjoyed it!
(Just because someone wanted to know!)
What is a pixel?
It is a single spot which can represent any colour within the bounds of physics for the device.
How can we understand pixels?
Firstly let us think of some units of measurement:
kilo K 1 000
mega M 1 000 000
However in Computers:
1024 is a kilobyte (kB), 1024 x 1024 is a megabyte (MB)
(mibibytes MiB in binary 220 same size as a MB, not an SI measurement)
In Cameras to find the Dots per inch we use this formula:
Resolution = Print Size
Dots Per Inch
With colour about 250 dots per inch is about the minimum amount of dots that are needed for the human eye to see before an image begins to look a bit broken up and made of squares.
(It might be useful to think of being close to a Monet picture.)
A Nikon chart for some cameras has some Megapixel cameras with these pixel sizes:
Megapixel | Resolution of Camera |
10.75 | 3872 x 2592 |
12.9 | 4228 x 2848 |
16.9 | 4928 x 3264 |
So what can you reasonably expect with a portrait shot on the 10.75 Megapixel camera.
Can we do a 16 x 24 inch? To find out we must calculate the DPI.
(DPI) We calculate the Values of X and Y as below.
3872 / X= 16 (Answer X= 242)
2048 /Y = 24 (Answer Y= 85)
So 242+85 = 327 DPI This would call a good quality picture to look at, as for it’s content that is a whole other story.
However the same camera printing to 32 x 48 inches would give 168.5 DPI you will see squares!
Want your own copy of this a PDF: