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Questions tagged [parsing]

Questions about built-in/custom parsers or parsing techniques.

11
votes
1answer
126 views

Lexical scanning and parsing in a toy language

I'm trying to do lexical scanning and parsing in a toy language. One with just functions (of the form $f(a,\,b,\,c,\,...)$, ended with semicolons) and special tokens (such as ...
2
votes
0answers
34 views

Confusing behavior for GrammarRules and GrammarApply

I have been experimenting with GrammarRules in an attempt to create a parser for text downloaded from the web. I have been using Interpreter to help understand the behavior of GrammarApply. Here is a ...
11
votes
1answer
94 views

Precedence of cell group tokens over package's expressions

Bug introduced in V10.4 or earlier and persisting through V11.3 [CASE:4072996] ...
9
votes
4answers
1k views

How to convert a string having nested parentheses into an expression?

I am a Wolfram Language/Mathematica beginner and trying to convert STEP ISO10303 commands into geometrical regions. A simple command looks like ...
5
votes
1answer
191 views

How to determine if RHS of first order ODE is separable or linear or neither? Parsing problem

Introduction This is really a parsing question. But the context is that given the right side of first order ode, I want to automatically determine the class of the RHS. It can be either separable, ...
0
votes
0answers
24 views

Parsing Module[…] creates additional Temporary symbols

Why this happens? ?? x$ Hold[Module[{x}, x]] ?? x$
17
votes
1answer
331 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 ...
7
votes
2answers
221 views

Getting the front sign of an expression. Positive or negative for formatting only

This is for the purpose of generating a string (actually it will Latex string, but that is not important). I need to generate string as ...
5
votes
1answer
52 views

Can we make preread replacements in an *.m* file before being run?

This the second question of (152743), the preamble of which is reproduced here: Those who don't have/prefer the front end of Mathematica will either use a plain ASCII editor to write a script in an ...
5
votes
1answer
44 views

Can we make new definitions for InputForm in packages?

Those who don't have/prefer the front end of Mathematica will either use a plain ASCII editor to write a script in an .m file or just use Mathematica directly from ...
1
vote
0answers
60 views

Scraping XML Paragraphs with URLs

I've been working on scraping an article from CNBC. The link is here I want to scrape the main body, and the code I have so far is this: ...
1
vote
1answer
86 views

Ugly Gaussian symbolic integration, how to extract coefficients and exponent argument?

I have a very ugly function with 157 terms that I want to integrate over three variables. Each term is a Gaussian integral in those variables multiplied by a polynomial in the variables. However, in ...
3
votes
1answer
254 views

Pulling Out Values from JSON Association

Having a bit of trouble pulling a value out of a JSON Association here. I am scraping this website: http://www.msn.com/en-us/money/stockdetails/history/fi-126.1.BY.NYS I want to scrape the closing ...
0
votes
0answers
231 views

HTTP Status Code 403

I'm working with some scraping and have run into a bit of a problem. The website I am scraping is this: https://seekingalpha.com/symbol/CRM/stocktalks I am essentially trying to scrape the "stock ...
1
vote
1answer
49 views

Extracting Certain Areas of JSON

I've been working with some web scraping and have run into a wall. The website I'm working with is this: https://seekingalpha.com/symbol/TWLO/stocktalks I am trying to scrape all of the "stock talks" ...
2
votes
1answer
164 views

Parsing and Extracting XML Content

I've run into a little question while trying to parse XML. This seems like a rather simple task, but for the life of me I cannot figure it out. I pull up the XML of the website using the following ...
2
votes
2answers
241 views

Parse command line arguments

I have been trying to parse command line arguments. There are a couple of types of options. 1. Mandatory 2. Optional 3. Alternative There are built-in/3rd ...
6
votes
0answers
78 views

Infix non-ASCII operator needs a space to be parsed correctly in a script

Bug introduced in 9.0 or earlier and persisting through 11.1 First off: ...
5
votes
1answer
708 views

How to parse JSON

please forgive me if this is obvious, but I have some JSON: ...
3
votes
0answers
32 views

Unexpected behaviour with WordSeparators and Read [duplicate]

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

Context inside Do[…]-loop

Consider the following code: Begin["mycontext`"]; myvar = 7; Print[Context[]]; Print[Context[myvar]]; End[]; with the output mycontext` mycontext` Now ...
3
votes
2answers
431 views

Reading a text file and parsing only the text between two delimiters

How are you? I'm a chemist with almost no experience with Mathematica, but I'm thinking of using it as a tool for my Ph.D in Computational Chemistry. My Quantum Chemistry software (ORCA) generates a ...
1
vote
2answers
139 views

How is a single tilde parsed?

How is a~b parsed and evaluated? I would expect an error, but it goes through without any complaints, yielding no apparent output. At first I thought it evaluated ...
4
votes
1answer
53 views

How do I import a Dataset that contains lists?

The very first example in the Dataset documentation is the following: ...
3
votes
1answer
81 views

How to use MakeExpression for single characters

Here is code that I thought would make the front end parse f as BigFunction: ...
9
votes
4answers
888 views

How to get the longest bracket pairs from a string

In C#, we can use regular expression to do some balancing groups, like we can get {<aa <bbb> <bbb> aa>, <<dfa>a>} from ...
18
votes
4answers
808 views

Is it important that the front-end has a built-in parser?

The Notebook interface has a parser that seems aware of all operator-precedences, allowing us to step through the expressions (rather: Box-) hierarchy with Ctrl+. This is extremely convenient, saving ...
6
votes
1answer
65 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, ...
2
votes
0answers
101 views

SymbolicC/SymbolicCUDAFunction generating C/C++ parser?

I wish to do some program transformation and analysis. Is there any package that generates SymbolicC expressions from C code? In a sense I'm looking for the ...
3
votes
1answer
82 views

How to speed up accidental large output?

From time to time I accidentally let large expressions like RandomReal[1., {10^5, 10, 10}] reach the front end. The computation of the result is quite fast (...
9
votes
1answer
192 views

Why is this syntax for patterns with Optional values not supported?

I want to express Optional[PatternTest[Pattern[a,Blank[]],t],1] concisely. a : _?t : 1 is not quite this but works: ...
4
votes
0answers
78 views

Weird bug with Esc, string, and underscore? [closed]

There seems to be a bug with esc key, strings, and underscores. For instance, see the following code: a = f["1_2"]; If an esc character is typed anywhere ...
1
vote
2answers
86 views

Use cases to exclude data values over a certain threshold

I am trying to parse data output from a fluorometer. My output is basically signal intensity over time. So I have a list of 2 value lists with the first value time and the second signal e.g., ...
8
votes
2answers
232 views

FullForm with context for each symbol?

FullForm strips the context for any symbol that can be found on the Append[$ContextPath, $Context]: ...
0
votes
1answer
161 views

How to read a part of huge matrix saved in a TXT file as single expression?

I saved a huge matrix of numbers with dimensions {400, 4001, 2} using Put and got a TXT file formatted in the following way: <...
5
votes
1answer
193 views

How to get “one Cell - one line” code format inside of NB files?

The PageWidth option controls the way the Cell's content is displayed, not the manner it's written in a ...
21
votes
2answers
566 views

Shell Emulation inside Mathematica

I am trying to create a Mathematica/shell syntax hybrid. I would like the following command wget -qO- "http://google.com/space line break\"" $var to be ...
4
votes
1answer
214 views

When does Mathematica insert parenthesis into expression?

expr//HoldForm usually returns identical expressions as input, but sometimes parenthesis are inserted. I tried to interpret this behavior as an attempt to eliminate ...
13
votes
2answers
815 views

How to parse a clojure expression?

Clojure is a lisp-like language that runs on JVM and in Javascript. I just started learning it and I'm building a simple parser with Mathematica to understand and visualize it. Like other lisps every ...
3
votes
1answer
76 views

Skipping commented in a stream from OpenRead

Is there a solution to skip comments in text files that are imported with OpenRead? I know there are solutions for Importand <...
3
votes
1answer
86 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 ...
4
votes
3answers
1k views

Importing CSV with multiline text fields

Bug introduced in 8 or earlier and fixed in 11.2.0 Here is a valid CSV: a1,b1,c1,d1,"e1 e1 e1" a2,b2,"c2 c2 c2",d2,e2 It has two rows and five columns, and ...
4
votes
1answer
208 views

How to get the list of links in a Wikipedia article in order of appearance

I can get a list of links in a Wikipedia article using WikipediaData: ...
2
votes
0answers
75 views

Where do the radicals end?

In an early iteration of this question on the Mathematics SE, the radicals weren't properly formatted, so they only had the √ symbol with no indication of which terms were supposed to be ...
4
votes
2answers
177 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 ...
0
votes
0answers
516 views

How to prevent space trimming when importing HTML with ImportString?

I am importing a HTML-formatted string with ImportString[string, "HTML"] to properly parse all HTML-escaped characters like ...
30
votes
0answers
453 views

Front end goes wild with named slots

Bug introduced in 10 and persisting through 11.3.0 Assume the following simple expression {#"Test"}& Now go in front of the ...
15
votes
0answers
187 views

Why does the Ver. 10.0 FrontEnd lose matching of parentheses when we insert quotations?

I am running Mathematica 10.0.1 on a four-year old iMac running OS 10.6.8. The following irritating behavior occurs regularly: I have a list with parentheses, and later on I need to add something to ...
0
votes
2answers
125 views

Extracting part of an expression

My goal is to solve $(\alpha - \dfrac{1}{\alpha}) - (\beta- \dfrac{1}{\beta}) = \dfrac 1 n$ where $\alpha$ and $\beta$ are rational and $n$ is a positive integer. Towards finding a particular solution,...
4
votes
1answer
226 views

Parsing string with nested information

I am trying to parse a string, but I have no idea how to solve the following problem ...