Questions tagged [streams]
A source of input or output: files and pipes are both examples of general Mathematica objects known as streams.
104
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Using Get with a few symbols to continue work in a later session [duplicate]
I have a notebook where I calculate integrals that take a long time to evaluate.
Let's say that I assign each evaluation to a symbol:
...
- 353
3
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0
answers
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OpenRead with Method->"GZIP"
Aim
I'm trying to "Low level" read data from a large "GZIP" file as an InputStream.
Previous answeers
I ...
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votes
1
answer
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Plotting phase plane in Filippov systems
I wanted to plot vector fields and nullclines for Modified Rosenzweig-MacArthur Model.
and I have a problem plotting p1 and p2 in the same graph on top of each other(I want the vector fields arrows in ...
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How to extend length of the streams in this StreamPlot
Is it possible the force the streams in StreamPlot[] to extend the full range of the graphic given specific points of my choosing? For example, notice the streams for the following code are short. I ...
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1
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Wolframscript: Removing prepended message from Print in slave kernel
I am running a parallelized algorithm using WolframScript and inside the function being passed to the various kernels, I have print statements that track the computation and output the print ...
- 557
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How to plot field line with exact starting and ending position continuously
As the title suggested, I want to plot the electric field lines with exact starting and ending position continuously.
The code is like this:
...
- 55
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2
answers
102
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Memory preserving computation in chunks
I would like to do the following:
Make a table
tab1={{i1,b1,c1,d1},{i1,b1,c1,d2},...,{i1,b1,c2,d1},...,{i1,b2,c1,d1},...{i2,b1,c1,d1},...}
for the given range imin < i < imax.
Make some ...
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1
answer
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How to read doubles from specific location of a large file
I have a 1GB file in a proprietary format that is a mix of ASCII characters and doubles (floating point numbers). I need to read in a sequence of twelve doubles. They are in consecutive bytes of the ...
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134
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Errors with opening and closing file streams
I'm fairly new to Mathematica programming. I'm writing a small program that needs to handle text file streams to write output to and read input from them.
Although I'm closing the file streams at the ...
3
votes
1
answer
77
views
How can I save the output from AudioRecord?
I'm trying to save a recording using AudioRecord. My recording gets overwritten even if I save the output in a fresh cell. This illustrates the issue:
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0
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How to stream NSE option chain data into mathematica
I'm trying to stream option chain data into mathematica from the
url: https://www.nseindia.com/api/option-chain-indices?symbol=BANKNIFTY
...
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3
votes
1
answer
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How to get StreamPlots where the density of arrows adapted (discretization ) adapts to the presence of funnels, saddle-points, etc?
I want to draw a phase portrait where the density of arrows adapted (discretization ) adapts to the presence of funnels, saddle points, and other phenomena. For example, in the code attached, the aim ...
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2
answers
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How to wait for new input from file InputStream
I'm trying to open a file to read and do some processing indefinitely until I decide to abort:
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- 618
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vote
0
answers
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Combine two streamplots with different position dependent color functions
Building from replies to other posts I have come up with a combination of two stream plots which has
a position dependent color function for stream lines which the same for the two plots
a way to &...
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1
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How can I make the vectors (vector heads) larger in a StreamPlot?
In my StreamPlots, the vectors can hardly be seen, in particular, since the heads of the vectors are so small.
Can I change this?
Example:
...
- 193
2
votes
1
answer
164
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Phase portrait on the sphere
I have that $(x,y)\in S^1$, i.e. on the sphere, and in Mathematica, the ODE system
...
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votes
2
answers
144
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Converting Strings to Reals in a List
I am new to Mathematica and working with streamed data:
...
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1
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63
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How to do computations with a specific column of a stream?
I'm trying to calculate the mean of a specific column of a huge dataset (given as .csv-file) using a stream in mathematica.
I tried the following:
...
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3
votes
2
answers
149
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How do I import a 1 gig text file by only importing the last 3 lines of every 10 line chunk?
I am trying to get the last three lines of every 10 line chunk into mathematica as a data variable. The text file has 3 columns. For example:
...
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answer
65
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1
vote
1
answer
109
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write output to stream and also print it
I tried to save the Print[] output to a file using this code:
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0
answers
74
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4
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answers
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Is there an equivalent to "Open Update"
I'm writing a binary file that contains a header followed by the data.
The header contains the length of the data.
The data is written first, skipping past the header.
Once done, I would like to ...
- 41
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answers
163
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Reading through file one line at a time, running out of RAM [closed]
I have a handful of files (some of which are very large), and I would like to loop through them one line at a time, run a calculation, and then write the result of the calculation to a new output file:...
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0
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54
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Issue with StreamDensityPlot
I'm plotting a complicated vector field that is yielding the following particular StreamDensityPlot. I'm using the following command to plot it:
...
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votes
1
answer
207
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How do I reliably read from stdin using wolframscript?
I am trying to direct a stream of data to a wls script in a command line environment. Wolframscript provides the ...
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votes
1
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238
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Vector field Stream?
The following graph shows the vector plot. How can I plot the solid lines which represents how the vectors are spatially varying and both on the same graph (vector plot and stream field)?
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answer
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Optimize Use of PeakDetect in Mathematica
I am quite new to Mathematica and I am looking for some advice in order to improve and optimize my code.
Here is what I am trying to do:
Open a stream
Read the stream line by line and store it in "...
- 103
1
vote
2
answers
174
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Reading CSV data from a stream [duplicate]
I'm trying to figure out how many rows/records my csv file has, which I have to stream because it's quite large.
Can someone tell me if my approach works and how I can get it to loop through the ...
2
votes
0
answers
266
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How to force Close of opened stream when stream write previously failed (bug in opening stream twice)?
I opened a stream like:
str = OpenWrite[NotebookDirectory[] <> "myStream.tsv"];
and made an error when writing the first line (meant to be the tsv headers):...
- 435
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votes
2
answers
163
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What is the fastest way to read the new lines in the dynamically updatable file?
I'm writing a log to a simple .txt file and want to read the last few records using Mathematica. But there are some problems.
f = OpenRead["logs.txt"];
Skip[f, ConstantArray[Number, 2], 1];
Read[f, ...
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answer
179
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Streams in parallel kernels. Writing in multiple files in ParallelDo loop in Mathematica
I need to write data in multiple files in ParallelDo loop:
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2
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2
answers
65
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Naming indexed output streams
I need to write into multiple files in a Do loop.
Hence, I tried to open multiple streams:
...
3
votes
2
answers
211
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Join two datasets with a function similar to Vlookup [Big Dataset and Efficiency issue] - Wizards are welcome!
I am working on a huge dataset and I have a lot of data formatted in XML, we are talking about a couple of GBs. For this reason I am currently using the stream function to read them and extract the ...
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0
answers
89
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Why does ReadString complain about the stream not being opened in binary format?
This works fine:
...
- 231k
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votes
0
answers
148
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LibraryLink: How to read from a Mathematica stream in C?
Mathematica has a flexible streams interface. Functions like Read can read from a "stream" that may be backed by a file, pipe, string, network resource, etc. We can ...
- 231k
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How many records? In a file (streaming)
I want to know how many records a file (large data) contains...
with streaming...like this:
...
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views
Communicating with server over Websocket using SocketConnect
I am trying to connect to a web socket feed of Gdax. The documentation is here, https://docs.gdax.com/#websocket-feed. There is no account needed and the information is public. I have successfully ...
- 1,269
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108
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Is it possible to parallelize reading in Mathematica?
I have a gigantic data file that needs to be processed. I am reading it in chunks using ReadList with an InputStream. In my ...
- 291
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votes
2
answers
101
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Explicitly control newline behaviour when writing strings with arbitary encoding
On Windows system, Mathematica by default opens stream which will automatically transform any "\n" into "\r\n". But I want pure ...
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20
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1
answer
414
views
Is building an event-based parser possible/reasonable in Mathematica (WL)?
Too long? Go to Problems section
Background
I like to learn by doing small, sometimes artificial, projects. Among other things I had 'parsers', and 'stream methods / streams in MMA' on my to learn ...
Kuba♦
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Matrix Vector multiplication for very big matrices (>>RAM)
Problem
Suppose a matrix-vector product of the form $M\vec{v}$ should be calculated where the amount of storage needed to store $M$ is noticeably larger than the available RAM on a machine. What is ...
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How to export result from SQLResultSet into a csv
I have a sql query which produces very large data from a remote server but the data is too large to fit into memory all at once. So i want to read and export it sequentially into a csv. I am using the ...
- 8,667
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1
answer
39
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Read not advancing StreamPosition [closed]
[MMA 11.0, Win7 64bit]
I have a number of CVS files of ~1-2GB, millions of rows, so I want to read them in records, chunks building on Albert Retey's answer to this question
I assumed, and the ...
- 2,480
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votes
0
answers
64
views
Why ReadList ignores NullRecords for Number?
When thinking on this recent question the immediately obvious solution which came to my mind was to use ReadList with options ...
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6
votes
1
answer
235
views
Is there a way to redirect the output from `Echo`?
The newish function Echo is tremendously useful in quick-and-dirty debugging, since you can stick it pretty much anywhere in an expression and get feedback about ...
- 18k
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votes
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answers
37
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Unexpected behaviour with WordSeparators and Read [duplicate]
I am confused about how Read separates elements.
The following all work fine:
...
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votes
1
answer
73
views
How to get the standard error stream for a ProcessObject?
When you run an external program using RunProcess, the program will run to completion and you will receive an association containing the exit code, stuff that went ...
- 18k
6
votes
1
answer
223
views
wolframscript creates tons of log files
On Linux, wolframscript seems to create log files in .Mathematica/ApplicationData/ProcessLink/Streams
for example:
...
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