Questions tagged [counting]
Questions on counting subparts of expressions, based on certain criteria. This is to be used with primary tags such as list-manipulation or string-manipulation, with the primary tag indicating the specific use case.
95
questions
7
votes
7
answers
360
views
Accumulated instance count of each list element
Given a list with repeated elements, for example:
list = {m, i, s, s, i, s, s, i, p, p, i}
I'd like to determine, for each position in the list, how many times the ...
- 1,325
3
votes
4
answers
88
views
Is there a better way to calculate the number of codewords of weight $i$ in a list of codewords?
Background Info
I am interested in a better way of doing the following:
I want to find the weights of the following codewords (the weight of a codeword here can be defined as the number of nonzero ...
- 481
6
votes
6
answers
411
views
Count all co-occurances of a pair of strings in a list of lists
I am trying to obtain a co-occurance matrix for pairs of names in a collection of groups of names.
So, I have a collection of letters in small groups, such as
...
- 2,027
0
votes
0
answers
55
views
Using Count[] on a numerical list with approximate numbers
I have a matrix, SpinOp, for which I obtain the Eigensystem using {evalSpinOp,evecSpinOp} = Eigensystem[SpinOp]. I need to ...
- 431
8
votes
5
answers
281
views
Values of counting functions
I have a table of integers, say A, and consider the counting function C, which, for a given x, gives the number of elements in A which are less or equal to x. Next, I want to plot C(x) in some range, ...
- 195
3
votes
1
answer
182
views
Count occurences of number in list of lists
I have a nested list of numbers, something like satisfied = {{1, 5, 6, 2, 1, 2}, {1, 5,,8, 6}, ..., {5, 6, 1}} and I want to count the number of occurences of 1 in each list. I know there is 1000 of ...
- 33
2
votes
4
answers
220
views
Counting number of points in fluctuating lines that fall within a circle
I have a list of points pts that fluctuate around some mean line. pts is pre-sorted by the projection of the points onto this ...
- 239
3
votes
3
answers
190
views
0
votes
1
answer
30
views
Confusing abnormalities observed when counting a specific operator in an expression [duplicate]
Recently I have met with some confusing abnormalities when trying to determine if there is a specific operator (usually Plus[] ) in an expression by programming. ...
- 473
5
votes
3
answers
161
views
Listing all Index Possibilities Given a Vector and Indexed Set
Let's say I am given a vector $v=(5,2,-2,-4,3)^T$ and $\alpha \in \{-1,1\} $. I want to find all indices $(\alpha,i)$ such that $\alpha v_i >0$, where $v_i$ is the $i$th entry of the vector $v$ ...
8
votes
6
answers
321
views
How to sort and extract a list containing products
I've some difficulties with lists containing products as elements, e.g. list = {A B A, A K B, A K R}, where A and B are from the same 'family', let's call it sector ...
- 204
1
vote
1
answer
77
views
Compute the length of each string in a set [closed]
Say I have done some computation, and it gives me the following set of string:
...
- 177
2
votes
1
answer
63
views
Counting the number of elements
I have the following output:
{{{0, 1}}, {{1, 1}, {1, 2}}, {{2, 1}, {2, 3}}, {{3, 1}, {3, 2}, {3, 3}, {3, 4}}}
Using Length[] on ...
- 1,941
1
vote
0
answers
109
views
How to count the amount of times an element appears seperately within a nested list [closed]
Beginner at using Mathematica, and having trouble with nested lists. For example, the following output for 15 coinflips every day for a year:
...
- 11
2
votes
1
answer
41
views
ResetDirectory causes a fail on stored file names
Consider some directory dir with sub dirs and files. Our aim is to count the no of files in dir (not in sub-dirs, just the dir.)
...
- 1,114
1
vote
1
answer
67
views
Counting the number of occurrences of all groupings (consecutive occurrences of the same number) in a list
If the variable "digits" contains a sequence of numbers how to count how many times each grouping of a number occurs? For instance, for number $1$ how many times it occurs once consequitivly ...
- 542
2
votes
2
answers
232
views
Counting the number of occurrences of specific values in a list in specific intervals
If the variable "digits" contains 10,000 digits from 0 to 9. How can the number of occurrences of 1s and 2s be counted in every 1000 digit intervals, that is to say the number of 1s and 2s ...
- 542
0
votes
1
answer
75
views
Count heads: e.g. neglect all terms $\sin(x) \sin (y) \sin (z) \sin (w)$ for all values of the argument
I have a polynomial (functional) expression $E[F]$ in terms of a function $F$.
I want to take an $F$-cube truncation in the sense that I want to and make terms of the form $F[w]F[x]F[y]F[z]$ vanish ...
- 155
4
votes
2
answers
353
views
How do I count zeros in sublists?
I have an array RandomInteger[1,{100,100}]. How do I count zeros in each sublist so that I have a list which gives the number of zeros of each sublist in the array?
- 43
7
votes
1
answer
281
views
In Wolfram Mathematica, who do I query the result of a Counts operation efficiently and conveniently?
Setup
Say, I'm given a dataset, like the one below:
titanic = ExampleData[{"Dataset", "Titanic"}]; titanic
Answering with:
And I want to count the occurrences ...
- 243
10
votes
2
answers
300
views
`Count` for `SparseArray`
Why does Count not work with SparseArrays, and is there any function I can use to replace it?
What would be an efficient ...
- 499
1
vote
2
answers
76
views
Counting the number of rows that contains specific numbers in specific cells
I'm trying to find a way to count the number of rows in a matrix that contains specific elements in specific cells.
For example, suppose I have the following matrix
...
- 393
-1
votes
1
answer
37
views
Adding up a list of rules
Here's the problem: I take a count of a count, so that I end up with a list in this format:
Table[Counts@Counts@Join[dKm[[i]], Pick[data1, ccKMedoid, i]], {i, 5}]
...
- 399
1
vote
1
answer
44
views
Putting a Count function for a matrix, in a loop
previously i had a doubt on how to assign different rows with certain values using a special function, which i later figured out by using the far more superior "DO" Loop. At present i have two ...
- 13
5
votes
3
answers
257
views
Program that can count deficient numbers
Using Mathematica, I want to make program which can solve the following question.
What is the number of deficient numbers less than 100?
Please help me.
- 57
3
votes
3
answers
421
views
count conditional items in list
I have a list of the form:
{1,1, (1 if x>y, -1 if y>=x), -1}
I want to count the number of 1's in the list. The output I'm looking for is something of the ...
- 343
2
votes
0
answers
102
views
Finding percentage of points within tilted ellipse?
I am trying to find the number of data points that I have that are within a tilted ellipse that I have generated to represent the 68% confidence region. I generated some data using:
...
- 399
1
vote
2
answers
86
views
Using Count and Rotate left
Q. Use RotateLeft and Count to find the number of planets detected by each method, presenting the result in a list of the form {{D, n1}, {R, n2}, {T, n3}}.
...
- 199
2
votes
2
answers
260
views
Count number of individual operations
Im interested in counting the number of operations required to evaluate a given formula. Let me give you an example.
Lets say I have entered the expression $\dfrac{\operatorname{Sqrt}[\operatorname{...
- 1,134
9
votes
6
answers
3k
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How do I count the number of elements in a list which are between two determined values?
I have a long list (apprx. 10000 elements) of numbers. I want to count the number of elements between two determined vallues a and ...
- 6,577
0
votes
1
answer
273
views
Fast way to count distinct pairs of integers
I have a association list, S, whose size is about 5*10^4. I also have a function F which takes in ordered pairs of elements from S, and spits out ordered pairs of integers. There is some amount of ...
- 439
4
votes
1
answer
110
views
Counting the number of strings starting with "t" and containing 2 vowels and 2 consonants
I generated a list of strings that match the criteria in the title as follows:
...
- 1,581
8
votes
3
answers
829
views
Count number of occurences of particular numbers in list
I have a list of numbers which I have rounded and now all numbers are divisible by 5.
...
- 185
4
votes
2
answers
64
views
Making polynomials representing frequency of a character in a list
Suppose I have the following list:
l={{"a"}, {"a", "h"}, {"a", "d", "k", "r", "v"}, {"a", "b", "c",
"k"}, {"a", "b", "c", "s", "u"}}
this list made of the ...
- 2,806
2
votes
1
answer
424
views
How can I get the count of how many times a string appears in my list? [closed]
I have a list of strings, like so:
{"aa bb", "cc dd", "aa bb", "aa bb", "cc dd", "ww ss", "ss ss", "kk mm"}
I know WordCounts ...
- 891
3
votes
3
answers
149
views
How to creates a Counts[] function that includes zero?
In the following example, I'm trying to how many times each integer 1-n appears in list 'a'. But if an element did not appear in a list, Counts[] creates an association that returns the element ...
- 4,553
0
votes
1
answer
118
views
Count sublists containing certain strings
I have a nested list which looks like:
and I would like to count the following:
all sublists containing {n_,n_} && {n_,n_,n_}
all sublists containing {l_,l_} && {l_,l_,l_}
all ...
- 109
2
votes
2
answers
82
views
Counting the number of Configurations in an Array with Constraints
Consider an array
$$\{a_i\}, i=1, ..., N$$
with periodic boundary condition, i.e. $i\equiv i+N$. $a_i\in \{0, 1\}$. I would like to count the number of configurations of the array $\{a_i\}$ satisfying ...
- 251
12
votes
3
answers
1k
views
Loop over a list of strings and increment letter count in a corresponding sublist
I have a 2D list as follows:
...
- 1,041
3
votes
2
answers
65
views
6
votes
2
answers
627
views
Bigrams and TF-IDF calculation
I want to create a bag of bigrams in a set of documents and calculate the TF-IDF vector of each document.
To calculate the bigram of the text I used the following code:
The small example of the data (...
- 1,989
2
votes
1
answer
241
views
How to count the number of eggshells in the image
My goal for this is to simply count the number of eggshells in the image.
Using color negate only leads to this
...
- 31
4
votes
4
answers
198
views
How can one efficiently find the (x,y) values of the rectangles that enclose a chosen % of nonrandom data points in mathematica?
A half hour of searching for answers did not give useful results.
This is typical data:
I need to find the (x,y) values of at least 6 rectangles with one corner at (0,0) and the opposite corner at (...
- 1,627
3
votes
1
answer
331
views
How many records? In a file (streaming)
I want to know how many records a file (large data) contains...
with streaming...like this:
...
- 31
2
votes
2
answers
65
views
Counting all matrices in a family obeying a certain rule
I would like to use the Count[list, pattern] method to count all 4x4 matrices with entries in $\lbrace 0 ,1 \rbrace$ that have a certain Jordan canonical form. The ...
- 145
0
votes
1
answer
126
views
Probability of empty urns for undistinguishable balls in distinguishable urns
Distinguishable balls in distinguishable urns is a well known problem in probability theory and can be easily simulated through Montecarlo simulations. Here we provide our code for n balls and m urns:
...
- 497
4
votes
4
answers
881
views
How to total the amount of zeros in a binary matrix
I have a 150 by 300 binary matrix. I would like to find the total amount of zeros in the matrix. I've been consulting online documentation for support, but am unable to use the "count" function ...
- 281
4
votes
1
answer
246
views
Count does not tally with total
I code the following to count events.
Count[Table[RandomInteger[{1, 6}], {i, 10}], #] & /@ Range[6]//Total
By right, if I total, I expect 10. Sometimes it ...
- 171
3
votes
2
answers
237
views
Most common prefixes in an English corpus (Hamlet)
There are many resources online showing how to get the most frequent letters in the english language. What I'm trying to do is get the most common word prefixes in the english language - i.e, take a ...
- 3,604
3
votes
3
answers
478
views
Count Column Elements in a Matrix [duplicate]
Let a square matrix be:
mat={{1,2,3},{4,5,6},{0,0,0}};
Get a total for each column:
In: Total[mat]
...
- 33