Questions tagged [streams]

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

Filter by
Sorted by
Tagged with
1
vote
1answer
32 views

write output to stream and also print it

I tried to save the Print[] output to a file using this code: ...
2
votes
0answers
59 views

How to read input stream with no newlines?

I have a script named stdout.wl: ...
0
votes
0answers
28 views

Selective read/write on a mx file

Consider an mx file to which has been saved the following data ...
4
votes
0answers
29 views

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 ...
3
votes
0answers
75 views

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:...
1
vote
0answers
42 views

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: ...
5
votes
1answer
114 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
votes
1answer
133 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
votes
1answer
2k views

How to read a named pipe on Windows?

Tried to open an Out named pipe from Powershell ...
5
votes
0answers
128 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
vote
2answers
87 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 ...
2
votes
0answers
159 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
106 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
votes
1answer
114 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
votes
2answers
49 views

Naming indexed output streams

I need to write into multiple files in a Do loop. Hence, I tried to open multiple streams: ...
3
votes
2answers
165 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
votes
0answers
68 views

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

This works fine: ...
11
votes
0answers
115 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
votes
1answer
283 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
votes
0answers
416 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
votes
0answers
86 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
93 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 ...
19
votes
1answer
364 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
370 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
vote
0answers
32 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
36 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
votes
0answers
62 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
votes
1answer
162 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
votes
0answers
36 views

Unexpected behaviour with WordSeparators and Read [duplicate]

I am confused about how Read separates elements. The following all work fine: ...
4
votes
1answer
53 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
179 views

wolframscript creates tons of log files

On Linux, wolframscript seems to create log files in .Mathematica/ApplicationData/ProcessLink/Streams for example: ...
1
vote
0answers
90 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: ...
7
votes
1answer
798 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
votes
0answers
842 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
277 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
593 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
votes
0answers
232 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
197 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
662 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
297 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
73 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
442 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
132 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
97 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
114 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
343 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
271 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
110 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
2k 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
382 views

StreamPlot segmented lines

I am plotting this vector field: ...