Questions tagged [filtering]
Questions on filtering or selecting data based on certain criteria. This is to be used with primary tags such as list-manipulation, string-manipulation or signal-processing, with the primary tag indicating the specific use case.
809
questions
1
vote
3
answers
159
views
1
vote
2
answers
104
views
1
vote
1
answer
42
views
Applying the MeanFilter function to individual array columns
How can I use the MeanFilter function on only the second or third column of my table?
...
- 359
0
votes
1
answer
54
views
Specific array filtering - code optimization
I have a nested list where all sublists have a length 2, eg:
{{1,2}, {1,1}, {3,4}, {3,5}, ...}
I need to filter it for two requirements:
Delete all sub-lists ...
- 1,904
5
votes
4
answers
241
views
Select elements from a list based on alphabetical order criteria
I have this code to generate the anagrams for a 6 letters word:
...
- 1,544
0
votes
1
answer
89
views
Error on RecurrenceTable with two variables [closed]
I am trying to simulate a second order filter unit step response with the RecurrenceTable instruction in Mathematica. There's a problem with the second-order ...
- 33
0
votes
0
answers
59
views
How to make the following pairing?
Consider the following list of identifiers:
Npart=5000;
ilist=Range[1,Npart];
And parameters belonging to the given identifier:
...
- 5,927
1
vote
1
answer
84
views
How to compute a weighted mean as a measure of central tendency?
Imagine I have data points in triplicates, as follows
$$
L=\begin{pmatrix}
p_{11} & p_{12} & p_{13}\\
p_{21} & p_{22} & p_{23}\\
& \vdots &\\
p_{n1} & p_{n2} & p_{n3}
\...
- 4,933
0
votes
1
answer
60
views
Pattern matching with DeleteCases
I'm using Mathematica 14.0 and I'm having a pattern match problem with DeleteCases. The example below illustrates the problem. I define a test string followed by two patterns that both nominally match ...
- 1
4
votes
6
answers
387
views
How do I reshape a list of this form?
I apologize if this is an already answered question, but I haven't been able to find it.
I have a long list that has this form:
...
- 361
5
votes
3
answers
229
views
Extraction of sublists containing certain sequence pairs
list =
{{a, b, c, d, a},
{e, f, a, b, c, d},
{a, b, p, q, c, d, g, h},
{c, d, p, q, a, b},
{a, c, b, d}};
I want to filter sublists of ...
- 82.6k
1
vote
1
answer
72
views
How to obtain positions of graphs satisfying certain conditions?
I first generate some random graphs, and then the following code can filter graphs with maximum degree 8.
...
- 2,059
2
votes
3
answers
103
views
I'm tired trying to get subsets
t={{a,b},{},{},{},{a},{a,b},{},{a,b,c},{},{b}}
s={{},{a,b,c},{a,b}}
Thread[Subset[t,s]]
I'm tired of trying to calculate:
{a,b} [which is the intersection [{a,b}, {...
- 107
2
votes
1
answer
83
views
Delete Null factors out of vector components
After running a very long loop, I get the following result given by a very long vector:
...
2
votes
3
answers
136
views
Issue in the calculus of inverse of terms from a list
to begin i want to warn you that i am a beginner in mathematica. I have to create a function that calculates the impedance total of an association of n (electronical) components.
So the formula is 1/Z(...
- 53
4
votes
4
answers
135
views
Extracting special sublists from a list
modified list
From a numerical evaluation I get examplary result
...
- 55.6k
0
votes
0
answers
104
views
Checking whether a set system is intersecting
I have a set of set systems g. I want to select from g those sets systems that are intersecting, that is for every two sets in ...
3
votes
1
answer
105
views
How to get the function-basis as they appear in the expression?
I have the following expression containing functions eg. Log, PolyLog etc,
...
- 1,897
0
votes
1
answer
100
views
Binary algorithm for finding the range of elements
Consider a sorted list of real numbers listz and some boolean condition condition that involves these numbers:
...
- 5,927
0
votes
0
answers
25
views
Performing Efficient Select on Data with Different Time Resolution
I have two data sources with different time resolution. For data source A (temperature) I have about 1 s time resolution. For data source B (spectra) I have 0.01 s time resolution. I would like to ...
- 490
4
votes
3
answers
667
views
How to remove a high accuracy numerical number from a list?
My numerical calculation gives a list of numbers
list = {-0.36, 0.2499999999999992, -0.21, 0.36, 0.36},
I want to delete 0.25 ...
- 4,739
3
votes
2
answers
180
views
Select a subset in the bit-strings with even 1s overlapped - thank you
Model 1
Consider the permutation list of 4-bit-strings:
list = Permutations[{0, 0, 1, 1}, {4}]
which outputs:
{{0, 0, 1, 1}, {0, 1, 0, 1}, {0, 1, 1, 0}, {1, 0, 0, ...
- 923
2
votes
1
answer
55
views
Is it possible to ask Mathematica to give/find this largest (absolute value) argument of $\cosh$ in the expression?
I have the expression exp in terms of Cosh functions:
...
- 195
5
votes
2
answers
153
views
DateSelect : columnwise selection applied to a matrix
Let consider :
A time interval (January given by Time)
A random set of values (Minimal example values given by Val)
as
...
- 754
3
votes
1
answer
61
views
Can you not use And[] inside a Select[]?
I have a list of lists of integers that are each sorted numerically. Here is a sample of it: {{2, 8, 9}, {3, 7, 9}, {4, 6, 9}, ...}. I wish to only pick out members ...
- 357
0
votes
0
answers
58
views
Comparing graphs in mathematica: shape vs. name
I'm trying to identify and remove duplicate graphs when contracting vertices. To illustrate this, I'll start with two simple graphs where I'm trying to create a function that can recognize them as ...
- 2,430
8
votes
10
answers
508
views
Merging and keeping only the sublists whose first two elements are equal
I have a list containing sublists.
...
- 1,118
6
votes
1
answer
243
views
7
votes
8
answers
189
views
Extracting up to $n$ elements after a specified marker from a list
I have a list from which I need to select up to two elements that follow each occurrence of a marker.
For example, the selected marker is ...
- 5,015
5
votes
2
answers
293
views
Express a "not equal to A or B" criterion in Select
I have a list of pairs of strings: myPairsList. I wish to Select all the pairs that do not contain ...
- 10.1k
4
votes
6
answers
509
views
How to find the most repeating row?
Consider the following table:
tab={{1,0,0,1},{1,0,0,1},{0,1,0,1},{1,0,0,1},{0,0,0,1},{1,0,0,0},{0,1,0,1}}
Could you please tell me whether there is a command which ...
- 5,927
4
votes
4
answers
340
views
1
vote
2
answers
101
views
How to extract the following data from the file?
Consider the following file. It has the form
...
- 5,927
13
votes
14
answers
889
views
Select from list elements greater than next element
Given
t1 = {3, 2, 8, 6, 1, 9, 4, 1, 5, 0}
I want to get all the elements which are greater than the right neighbor. The result would be
...
- 2,788
4
votes
8
answers
480
views
How to get a Table of pairs (a/b, c/d) where GCD[a,b]==1 and GCD[c,d]==1?
I am trying to make a Table pairs of (a/b, c/d) where GCD[a,b]==1 and GCD[c,d]==1. I have tried the following:
...
- 1,118
1
vote
2
answers
72
views
Selecting interesting graph positions with a button press/click or something similar
Assume that I have a graphList as shown below (a simple working example).
...
- 2,111
2
votes
2
answers
91
views
Looking for solutions to filter out one-sided angle pairs in line intersections
I posted something here a while ago, but I think it's a bit messy and difficult to understand. So, I'll create a new post to explain the concept and what I want in a different way, hopefully making it ...
- 2,430
6
votes
7
answers
612
views
Dropping disordered numbers in a list
I have a list of numbers like
l1 = (1,2,3,4,8) and clearly, l1 is in order (next number is greater than previous number).
Well, ...
- 445
10
votes
5
answers
2k
views
Find Roman numerals up to 100 that do not contain “I"
The question is from Elementary Introduction to the Wolfram Language, section 28 Tests and Conditionals: Find Roman numerals up to 100 that do not contain “I”.
What am I doing wrong that the following ...
- 673
1
vote
1
answer
68
views
Sumif and delete cells in Mathematica
I want to create a simple "sumif" formula like in Excel. However, I am desperate since I cannot achieve a result.
First, I am importing an excel file with lot of datas.
data = Import[
"...
- 11
3
votes
6
answers
705
views
Make a list of the first 100 primes, keeping only ones whose last digit is less than 3 [closed]
This is a question from an "Elementary Introduction to the Wolfram Language" Section 28: Tests and Conditionals. We are asked to "Make a list of the first 100 primes, keeping only ones ...
- 673
2
votes
3
answers
367
views
Finding transitive Boolean matrices
I am fairly new here and with Mathematica too.
I have a question regarding Boolean matrices but before this I did a random search and got this
Defining an arbitrary binary relation
But I am unable to ...
- 55
9
votes
4
answers
665
views
Check if a string is a date
I have a list of strings,
{"BD4675365", "Corp", "Managers", "Syndicate", "2021-03-08", "8434926"}
and I ...
- 2,203
2
votes
1
answer
54
views
How to select only particular values from the list using dialog windows?
Consider some list:
list = {"A","B","C","D"}
How to select only particular values from it using a dynamic dialog window ...
- 5,927
5
votes
3
answers
303
views
How can I select only rows where a column is equal to any value from some list? [closed]
Consider some data
data=Table[{RandomInteger[{0,10}],RandomReal[{0,1}]},10];
and some list
list={0,5,7,3};
How can I leave ...
- 5,927
1
vote
0
answers
58
views
Selecting elements with a particular slope
I have a dataset for which I want to identify 'groupings' based on three criteria, but only one of them is giving me a headache. The criteria are that each group must:
have a minimum number of points ...
- 1,438
1
vote
2
answers
75
views
How to leave only the columns satisfying the following condition?
Consider the following pre-generated table:
...
- 5,927
0
votes
0
answers
41
views
Optimization of conditions applying
Let we have some data generator, e.g. lazy tuples or permutations.
I need to select data by some conditions cond1, cond2, …, up to 5-6 conditions.
All of them need ...
- 1,904
0
votes
0
answers
45
views
Speed up Select Operating on a Large List with Multiple Criteria
I am using the following code to select stocks that have performance data starting before one specified date and ending after a second specified date, as follows:
...
- 1,334
11
votes
7
answers
773
views
Can I tell DeleteCases not to delete function arguments?
Given list = {1, 2, f[3, 4], {5, {6, g[7, h[8, 9]]}}, {f[10], 11}};
I want to get
{f[3, 4], {{g[7, h[8, 9]]}}, {f[10]}}
just ...
- 5,672