I have a Large RasterBrick, created through compiling a large number of .nc files and then manipulating in a few ways (cropping, collapsing, naming layers). I want to save this brick to a file on my laptop, so that I can access it without having to import all data and manipulate anew.
How do I do this? I think it should involve writeRaster, but I'm not sure how to specify the options.
My RasterBrick is 18 by 25, with 14975 layers, each named with the relevant date.
I tried this code from Save multi layer RasterBrick to harddisk:
outfile <- writeRaster(windstack_mn, filename='dailywindgrid.tif', format="GTiff", overwrite=TRUE,options=c("INTERLEAVE=BAND","COMPRESS=LZW"))
However, this code produce a tif file that holds a single 18 by 25 layer. I think it saved only the 1st layer of my RasterBrick, because if I bring in the saved .tif file and plot it, it looks identical to plotting the 1st layer of the original RasterBrick.
Did you look at outfile? Can you show it to us?
You should show what you do to "bring in the saved .tif". I am guessing that you do
raster('dailywindgrid.tif')
whereas you should be doing
brick('dailywindgrid.tif')
The comment/answer fr/ Robert solves my issue, with the one addition that one needs to specify the raster format. So I am now saving the file with this code:
writeRaster(StackName, filename='FileNAme.grd', format="raster", overwrite=TRUE,options=c("INTERLEAVE=BAND","COMPRESS=LZW"))
And that .grd file can later be opened using this code:
ImportName <- brick("FileNAme.grd")
How to read image data from .cr2 (raw image format by Canon) in C++?
The only one operation I need to perform is to read pixel data of .cr2 file directly if it is possible, otherwise I would like to convert it to any loss-less image and read its pixels' data.
Any suggestions?
I would go with ImageMagick too. You don't have to convert all your files up front, you can do them one at a time as you need them.
In your program, rather than opening the CR2 file, just open a pipe (popen() call) that is executing an ImageMagick command like
convert file.cr2 ppm:-
then you can read the extremely simple PPM format which is described here - basically just a line of ASCII text that tells you the file type, then another line of ASCII text that tells you the image dimensions, followed by a max value and then the data in binary.
Later on you can actually use the ImageMagick library and API if you need to.
I know that I can create a dta file if I have dat file and dictionary dct file. However, I want to know whether the reverse is also possible. In particular, if I have a dta file, is it possible to generate dct file along with dat file (Stata has an export command that allows export as ASCII file but I haven't found a way to generate dct file). StatTransfer does generate dct and dat file, but I was wondering if it is possible without using StatTransfer.
Yes. outfile will create dictionaries as well as export data in ASCII (text) form.
If you want dictionaries and dictionaries alone, you would need to delete the data part.
If you really want two separate files, you would need to split each file produced by outfile.
Either is programmable in Stata, or you could just use your favourite text editor or scripting language.
Dictionaries are in some ways a very good idea, but they are not as important to Stata as they were in early versions.
Are there some situation where I have to prefer binary file to text file? I'm using C++ as programming language?
For example if I have to store some large text file is it better use text file or binary file?
Edit
The file for the moment has no requirment to be readable from human. Are some performance difference, security difference and so on?
Edit
Sorry for the omit other the requirment (thanks to Carey Gregory)
The record to save are in ascii encoding
The file must be crypted ( AES )
The machine can power off any time. So I've to try to prevents errors.
I've to know if the file change outside the program, I think I'll use a sha1 digest of the file.
As a general rule, define a text format, and use it. It's much
easier to develop and debug, and it's much easier to see what is
going wrong if it doesn't work.
If you find that the files are becoming too big, or taking to
much time to transfer over the wire, consider compressing them.
A compressed text file is often smaller than you can do with
binary. Or consider a less verbose text format; it's possible
to reliably transmit a text representation of your data with
a lot less characters than XML uses.
And finally, if you do end up having to use binary, try to chose
an existing format (e.g. Google's protocol blocks), or base your
format on an existing format. Just remember that:
Binary is a lot more work than text, since you practically
have to write all of the << operators again, including those
in the standard library.
Binary is a lot more difficult to debug, because you can't
easily see what you've actually done.
Concerning your last edit:
Once you've encrypted, the results will be binary. You can
use a text representation of the binary (base64 or some such),
but the results won't be any more readable than the binary, so
it's not worth the bother. If you're encrypting in process,
before writing to disk, you automatically lose all of the
advantages of text.
The issues concerning powering off mean that you cannot use
ofstream directly. You must open or create the file with the
necessary options for full transactional integrity (O_SYNC as
a flag to open under Unix). You must write each record as
a single write request to the system.
It's always a good idea to have a checksum, just in case. If
you're worried about security, SHA1 is a good choice. But keep
in mind that if someone has access to the file, and wants to
intentionally change it, they can recalculate the SHA1 and
insert the new value as well.
All files are binary; the data within them is a binary representation of some information. If you have to store a large amount of text then the file will contain the binary representation of that text. The difference between a "binary file" and a "text file" is that creating the latter involves converting data to a text form before saving it. This is typically done so humans can read it.
The distinction between binary and text is usually made when storing data that is for computer consumption. Typically this data would not be text - it might be a list of numerical configuration values, for example: 1, 2, 3.
If you stored this in text format, your file could contain a list of human-readable numbers, and if you opened the file in Notepad you might see one number per line. But what you're actually saving here is not the binary values 1, 2, 3 - you're saving a string "1\n2\n3\n". Note that this string is 6 characters long, and the binary values (assuming ASCI) would actually be 49, 10, 50, 10, 51, 10!
If the same data were stored in binary format, you would store the numbers in the smallest useful space, and write the file as individual bytes that can often only be read by the code that created them. Opening this file in Notepad would likely display junk characters, because the data makes no sense as text. In this case you would be saving a byte array with actual values { 1, 2, 3 } - or even a single byte with the three values embedded. This could be much smaller than the human-readable equivalent.
Binary files store a sequence of bytes like all other files. You can store numeric values like integers per 4 bytes, characters per single byte, or even serialized class objects and anything you want.
When you know how to read a binary file (ie. you know what is stored in it) you can extract all the information from it. However, text files use text encodings like UTF8, ANSI etc. and they are intended to encode text characters to be processed by text editors.
Binary files are for machines only to interpret, whereas a text file, a human can also open and interpret its content.
So it depends whether you want your file to be readable by a human or not.
It depends on a lot of factors. I can think of two right now:
Do you require the file to be readable by humans?
Is compression a factor? A 10-digits number will take at least 10 bytes as text, but might take as little as four or two as binary.
All data is binary. You always need a machine to interpret it for you. Even if the data is compressed like protocol buffers, Avro, Thrift etc, it is binary, and if it is uncompressed, it is still binary. If you want to read protocol buffers by notepad, there is a two step process. Uncompress, and read. In case of text, this step of uncompressing is not needed. Same is case with encrypted. First unencrypted, and then read. Humans cannot read binary (as some commenters are mentioning). We still need notepad to interpret and display binary (so called text).
All data stored in a text file are human-readable graphic characters. Each line of data ends with a new line character.
In case of a binary file - data is stored in the same format as they are stored in the memory. There are no lines or new line characters. There is an end of file marker.
Moreover binary files show more efficiency for memory as they are stored in zeros and one's.
So, I have this program that collects a bunch of interesting data. I want to have a library that I can use to sort this data into columns and rows (or similar), save it to a file, and then use some other program (like OpenOffice Spreadsheet, or MATLAB since I own it, or maybe some other spreadsheet/database grapher that I don't know of) to analyse and graph the data however I want. I prefer this library to be open source, but it's not really a requirement.
Ok so my mistake, you wanted a writer. Writing a CSV is simple and apparently reading them into matlab is simple too.
http://www.mathworks.com.au/help/techdoc/ref/csvread.html
A CSV has a simple structure. For each row you seperate by newline. and each column is seperated by a comma.
0,10,15,12
4,7,0,3
So all you really need to do is grab your data, seperate it by rows then write a line out with each column seperated by a comma.
If you need a code example I can edit again but this shouldn't be too difficult.