I am using jpeg package to read an image into R. This creates an object of class nativeRaster. I take a portion of this image using [ operator. The resulting object is a matrix of integers. Attempting to save this object returns the error image must be a matrix or array of raw or real numbers. What should I do to be able to save this new image?
Below is a snippet to reproduce the error
imageFile = 'address of the jpg file'
outputFile = 'new file to write into'
image = jpeg::readJPEG(imageFile, native=TRUE)
output = image[1:10,1:10]
writeJPEG(image = output, target = outputFile)
I think the function writeJPEG takes image of type nativeRaster. I am not entirely sure about this but converting class of output to nativeRaster works for me.
class(output) <- "nativeRaster"
writeJPEG(image = output, target = outputFile)
Even though I was unable to find a solution, I am working around this by using solely imagemagick to crop the image.
system(paste('identify',
imageFile), intern = TRUE) %>%
regmatches(.,regexpr("(?<=[ ])[0-9]*?x[0-9]*?(?=[ ])",.,perl=T)) %>%
strsplit('x') %>% .[[1]] %>% as.double
will return the dimensions of the image and
system(paste0('convert "',imageFile,
'" -crop ',
sizeX,
'x',
sizeY,
'+',
beginningX,
'+',
beginningY,
' "',
outputFile,'"'))
will crop the image and save it to outputFile
Here sizeX and sizeY are desired dimensions of the cropped image and beginningX and beginningY designate the top left corner of the crop site on the image.
Related
I don't managed to read a bitmap which is in the Windows clipbard.
I first check the cliboard :
getClipboardFormats()
which give
[1] "bitmap" "DIB" "shell"
Then I tried :
image = readClipboard(format=2, raw=FALSE)`
and
image = readClipboard(format=2, raw=TRUE)
but I always obtain a NULL value for image !
Can someone explain to me how to do it?
I have a data in text file. The example of the text file looks like this:
"vLatitude ='23.8145833';
vLongitude ='90.4043056';
vcontents ='LRP: LRPS</br>Start of Road From the End of Banani Rail Crossing Over Pass</br>Division:Gazipur</br>Sub-Division:Tongi';
vLocations = new Array(vcontents, vLatitude, vLongitude);
locations.push(vLocations);"
Can I change it to like this in R?
eg.
latitute longtitude contents
23.8145833 90.4043056 LRP: LRPS Start...Tongi
Solution 1
That looks a lot like javascript code. Execute the javascript (using a web browser) and save the result to JSON, then open the file with R with jsonlite.
With your example, create this file and save it as my_page.html:
<html>
<header>
<script>
// Initialize locations to be able to push more values in it
// probably not required with your full code
var locations = [];
vLatitude ='23.8145833';
vLongitude ='90.4043056';
vcontents ='LRP: LRPS</br>Start of Road From the End of Banani Rail Crossing Over Pass</br>Division:Gazipur</br>Sub-Division:Tongi';
vLocations = new Array(vcontents, vLatitude, vLongitude);
locations.push(vLocations);
// convert locations to json
var jsonData = JSON.stringify(locations);
// actually write the json to file
function download(content, fileName, contentType) {
var a = document.createElement("a");
var file = new Blob([content], {type: contentType});
a.href = URL.createObjectURL(file);
a.download = fileName;
a.click();
}
download(jsonData, 'export_json.txt', 'text/plain');
</script>
</header>
<body>
Download should start automatically. You can look at the web console for errors.
</body>
</html>
When you open it with your web browser it should "download" a file, that you can open with R:
jsonlite::read_json("export_json.txt",simplifyVector = TRUE)
One problem is that the javascript code is created an array without names. So the names are not exported. I don't see how you could make javascript export it.
Solution 2
Instead of relying on a browser to execute the javascript code, you could do it directly in R with a javascript engine. It should give you the same result, but makes communication between the two easier.
Solution 3
If the file really looks like that all along, you might be able to remove the javascript lines that organize the arrays, and only keep the lines that define variables. In R, the symbols = and ; are technically valid, it's not too hard to rewrite the javascript into R code. Note this solution could be very fragile depending on what else is in your javascript code!
js_script <- "var locations = [];
vLatitude ='23.8145833';
vLongitude ='90.4043056';
vcontents ='LRP: LRPS</br>Start of Road From the End of Banani Rail Crossing Over Pass</br>Division:Gazipur</br>Sub-Division:Tongi';
vLocations = new Array(vcontents, vLatitude, vLongitude);
locations.push(vLocations);
// convert locations to json
var jsonData = JSON.stringify(locations);" %>%
str_split(pattern = "\n", simplify=TRUE) %>%
as.character() %>%
str_trim()
# Find the lines that look like defining variables
js_script <- js_script[str_detect(js_script, pattern = "^\\w+ ?= ?'.*' ?;$")]
# make it into an R expression
r_code <- str_remove(js_script, ";$") %>%
paste(collapse = ",")
r_code <- paste0("c(", r_code, ")")
# Execute
eval(str2expression(r_code))
I'm very new to R and beginner level at programming in general, and trying to figure out how to get hovertext in plotly to display a Japanese string from my dataframe. After venturing through character encoding hell, I've got things mostly worked out but am getting stuck on a single point: Getting the Japanese string to display in the final plot.
plot_ly(df, x = ~cost, y = ~grossSales, type = "scatter", mode = "markers",
hoverinfo = "text",
text = ~paste0("Product name: ", productName,
"<br>Gross: ", grossSales, "<br> Cost: ", cost,
)
)
The problem I encounter is that using 'productName' returns the Japanese string from the dataframe, which causes the plot to fail to render. DOM Inspector's console shows JSON encountering issues with the string (even though it's just encoded in UTF-8).
Using toJSON(productName), I am able to render the table, however this renders the hover textbox with the full information of the productName column (e.g., ["","Product1","Product2","Product3"...]). I only want the name of that specific product; just as 'grossSales' and 'cost' only return one the data specific to that product at each point on the plot.
Is there a way I can execute toJSON() only on each specific instance of 'productName'? (i.e., output should be "Product1" with JSON friendly string format) Alternatively, is there a way I can have plotly read the list output and select only the correct productName?
Stepping away from the problem to continue studying other things, I found a partial solution in using a for-loop:
productNames <- NULL
for (i in 1:nrow(df))
{
productNames <- c(productNames, toJSON(df[i, "productName"]))
}
df$jsonProductNames <- productNames
Using the jsonProductNames variable within plotly, the graph renders and displays only the name for each product! The sole issue remaining is that it is displayed with the JSON [""] formatting around each product's name.
Update:
I've finally got this working fully how I want it. I imagine there are more elegant solutions, and I'd still be interested to learn how to achieve what I originally was looking at if possible (run a function on a variable within R for each time it is encountered in a loop), but here is how I have it working:
colToJSON <- function(df, colStr)
{
JSONCol <- NULL
for (i in 1:nrow(df))
{
JSONCol <- c(JSONCol, toJSON(df[i, colStr]))
}
JSONCol <- gsub("\\[\"", "", JSONCol)
JSONCol <- gsub("\"\\]", "", JSONCol)
return(JSONCol)
}
df$jsonProductNames <- colToJSON(df, "productName")
Using the built-in "Import Data..." functionality we can import a properly formatted text file (like CSV and/or tab-delimited) as an image. It is rather straight forward to write a script to do so. However, my scripting approach is not efficient - which requires me to loop through each raw (use the "StreamReadTextLine" function) so it takes a while to get a 512x512 image imported.
Is there a better way or an "undocumented" script function that I can tap in?
DigitalMicrograph offers an import functionality via the File/Import Data... menu entry, which will give you this dialog:
The functionality evoked by this dialog can also be accessed by script commands, with the command
BasicImage ImageImportTextData( String img_name, ScriptObject stream, Number data_type_enum, ScriptObject img_size, Boolean lines_are_rows, Boolean size_by_counting )
As with the dialog, one has to pre-specify a few things.
The data type of the image.
This is a number. You can find out which number belongs to which image data type by, f.e., creating an image outputting its data type:
image img := Realimage( "", 4, 100 )
Result("\n" + img.ImageGetDataType() )
The file stream object
This object describes where the data is stored. The F1 help-documention explains how one creates a file-stream from an existing file, but essentially you need to specify a path to the file, then open the file for reading (which gives you a handle), and then using the fileHandle to create the stream object.
string path = "C:\\test.txt"
number fRef = OpenFileForReading( path )
object fStream = NewStreamFromFileReference( fRef, 1 )
The image size object
This is a specific script object you need to allocate. It wraps image size information. In case of auto-detecting the size from the text, you don't need to specify the actual size, but you still need the object.
object imgSizeObj = Alloc("ImageData_ImageDataSize")
imgSizeObj.SetNumDimensions(2) // Not needed for counting!
imgSizeObj.SetDimensionSize(0,10) // Not used for counting
imgSizeObj.SetDimensionSize(1,10) // Not used for counting
Boolean checks
Like with the checkboxes in the UI, you spefic two conditions:
Lines are Rows
Get Size By Counting
Note, that the "counting" flag is only used if "Lines are Rows" is also true. Same as with the dialog.
The following script improrts a text file with couting:
image ImportTextByCounting( string path, number DataType )
{
number fRef = OpenFileForReading( path )
object fStream = NewStreamFromFileReference( fRef, 1 )
number bLinesAreRows = 1
number bSizeByCount = 1
bSizeByCount *= bLinesAreRows // Only valid together!
object imgSizeObj = Alloc("ImageData_ImageDataSize")
image img := ImageImportTextData( "Imag Name ", fStream, DataType, imgSizeObj, bLinesAreRows, bSizeByCount )
return img
}
string path = "C:\\test.txt"
number kREAL4_DATA = 2
image img := ImportTextByCounting( path, kREAL4_DATA )
img.ShowImage()
My problem is that I have bunch of jpgs and I would like to overlay all of them to see a pattern.
I checked out this answer(Overlay two same sized images in Python) but it only shows how two images can be overlayed.
Here are the piece of code which shows I'd like to do.
for file in os.listdir(SAVE_DIR):
img1 = cv2.imread(file)
img2 = cv2.imread('next file name') #provide previous output file here (dst)
dst = cv2.addWeighted(img1,0.5,img2,0.5,0)
cv2.imshow('dst',dst)
cv2.waitKey(0)
cv2.destroyAllWindows()
One approach is to store all your images as a list, and then iterate through each overlapping pair of images and callcv2.addWeighted() on each element in your list, passing in the last aggregate image in as img1 to your subsequent call to cv2.addWeighted().
So for example, say you have 4 images, with names [img1, img2, img3, img4].
You could do
jpeg_list = os.listdir(SAVE_DIR)
for i in range(len(jpeg_list)):
aggregate_file = cv2.imread(jpeg_list[i])
next_img = cv2.imread(jpeg_list[i+1])
dst = cv2.addWeighted(aggregate_file, 0.5, next_img, 0.5, 0)
cv2.imshow('dst', dst)