Questions tagged [streams]

A source of input or output: files and pipes are both examples of general Mathematica objects known as streams.

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5
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1answer
68 views

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 ...
2
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1answer
99 views

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)? ...
10
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1answer
785 views

How to read a named pipe on Windows?

Tried to open an Out named pipe from Powershell ...
0
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0answers
32 views

Reading a chunk of data from a stream using Parallelization

I am trying to read a stream and perform some operations in parallel. Here is the logic of the code inside the ParallelDo: 1- Open stream 2- Read chunk of data 3- Close stream 4- Process the data ...
5
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0answers
119 views

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 "...
1
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2answers
65 views

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 ...
1
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0answers
97 views

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):...
9
votes
2answers
87 views

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, ...
2
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1answer
81 views

Streams in parallel kernels. Writing in multiple files in ParallelDo loop in Mathematica

I need to write data in multiple files in ParallelDo loop: ...
2
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2answers
41 views

Naming indexed output streams

I need to write into multiple files in a Do loop. Hence, I tried to open multiple streams: ...
3
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2answers
145 views

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 ...
2
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0answers
62 views

Why does ReadString complain about the stream not being opened in binary format?

This works fine: ...
10
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0answers
101 views

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 ...
3
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1answer
219 views

How many records? In a file (streaming)

I want to know how many records a file (large data) contains... with streaming...like this: ...
7
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0answers
324 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 ...
0
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0answers
77 views

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 ...
3
votes
2answers
88 views

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 ...
17
votes
1answer
353 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 ...
5
votes
1answer
260 views

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 ...
1
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0answers
30 views

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 ...
1
vote
1answer
34 views

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 ...
5
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0answers
57 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 ...
6
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1answer
130 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 ...
3
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0answers
34 views

Unexpected behaviour with WordSeparators and Read [duplicate]

I am confused about how Read separates elements. The following all work fine: ...
4
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1answer
46 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 ...
5
votes
1answer
167 views

wolframscript creates tons of log files

On Linux, wolframscript seems to create log files in .Mathematica/ApplicationData/ProcessLink/Streams for example: ...
1
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0answers
81 views

Why does using BinaryWrite make my file bigger? [closed]

I have a binary file 00010005.dat. I want to normalize the matrix so I use the following code: ...
4
votes
1answer
548 views

SliceStreamPlot3D or StreamPlot3D

I know that neither of the two functions listed in the title exist, but I basically replaced vector for stream to give you an idea of what I want. The most ideal would be ...
3
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0answers
726 views

How to visualize the vorticity of a 3D velocity field? [closed]

I sample a snapshot from a system with 50 particles including their position and instant velocities. The snapshot is a list of 3 position and 3 velocities values per particle. i.e. 50 lines each of ...
9
votes
2answers
254 views

Is there a way to create ZIP OutputStream ?

I want to write data to a file using compression. Is it possible to do that just in time (like in java ZipOutputStream). E.g. what I want: ...
27
votes
3answers
567 views

Can Mathematica edit large binary files in-place?

I have a very large binary data file (several hundred GB) which I would like to edit using Mathematica. The only edits required are a few isolated byte replacements—no insertions or deletions. Is it ...
3
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0answers
194 views

How to flush stdout stream?

I am aware that one can write to a terminal standard output like so: WriteString["stdout","Some stuff","\r"]; Note here that I am using a carriage return on ...
4
votes
1answer
158 views

How to read *all* input from stdin?

The answers given to this similar question won't do, because those solutions read only one line from stdin. I want to read all available lines, pretty much in the ...
4
votes
3answers
597 views

how do I to create a function similar to feof in C?

Using C language,I can use feof to test if the pointer at end of file. while(!feof(fp)) { //to do } But in the mma,I ...
3
votes
1answer
231 views

How to Terminate Read at EndOfFile

We are working on a project that reads in a stream, extracts information from it, and then needs to stop the calculation when it reaches EndOfFile. So for example,...
6
votes
1answer
68 views

Can Read[] apply a custom function automatically to the read values?

Read[stream, Number] will return a single read number. We can use a number of standard, documented types instead of Number, ...
11
votes
0answers
412 views

How to read and write data to open socket?

I am trying to open connection with socket. I am using this: ...
1
vote
1answer
117 views

Inconsistency of WriteString

Important Note A kernel or maybe Front End restart probably fixed the problem. I did something weird today which is evaluate Context[StringQ]="test`", perhaps that ...
3
votes
1answer
91 views

`ReadString` and `StreamPosition` behaving strangely with custom terminators

I've stumbled on a strange behavior while trying to use custom terminators for ReadString. When I use a simple String as the ...
5
votes
1answer
101 views

How can I dynamically display a stream position?

If I create a stream, str = StringToStream["how can I dynamically display the stream position"]; Read[str, Word] "how" then, when I use, ...
4
votes
1answer
275 views

Importing large datasets using streams

I work with large data sets with 22 columns and up to a million rows. Each row contains one observation with several variables. All variables are numbers. Simplyfied example: 1, 1, 2, 3, 4, 5, 6,...
4
votes
2answers
234 views

Parsing tab delimited file

Problem Description I have my data arranged in a tab delimited file and I'm trying to parse/access certain parts of it. As an example, I'd like to extract the number of points and the sampling ...
2
votes
1answer
104 views

Use e notation in Stream output

I'm trying to save the results of a huge Radia calculation. I evaluate the function in a loop at multiple locations. To export the data my first approach was to fill a Table and use the ...
2
votes
0answers
1k views

StreamPlot in 3 Dimensions

I would like to plot the vector equation $\left( {\begin{array}{*{20}{c}} {\frac{{ - a + \sqrt {{a^2} + 4bc} }}{c}}\\ {\frac{{ - a - \sqrt {{a^2} + 4bc} }}{c}}\\ 1 \end{array}} \right)$ as a stream ...
2
votes
1answer
350 views

StreamPlot segmented lines

I am plotting this vector field: ...
3
votes
3answers
333 views

ReadLine[file] after reopening a closed stream doesn't read at the beginning of file?

Take a text file from your system: file = OpenRead["path/to/your/file"] ReadLine[file] Close[file] Here ReadLine[file] ...
30
votes
2answers
680 views

Reading from a socket stream

I noticed an undocumented socket package (SocketLink) in Mathematica (Using version 10, not sure when it was actually added) and wrote a barebones HTTP responder ...
1
vote
1answer
282 views

ReadList can't read “.csv” data with correct line number?

Well, the problem was solved today. Since "testAll.csv" is generated by Java/Eclipse, and I noticed that the LineSeperator is "\...
1
vote
3answers
1k views

How to import files with headers?

R has excellent header supports such as read.table with header options. I don't want to mess up with text-processing or stream-processing. I am looking for a similar tool as in R because it saves a ...
3
votes
0answers
71 views

ScheduledTask output redirection [duplicate]

When a function is run repeatedly within a ScheduledTask its output is sent to Messages Window. When two or more ScheduledTasks are running their outputs are mixed in the Messages Window and this is ...