Questions tagged [map]
Questions about applying functions or operators to expressions, especially constructs that take advantage of Map (/@) functionality.
4
votes
2answers
157 views
Iterate MapThread with matrices
Consider a function f and a list p={a,b,c}. I want to get a list of
...
1
vote
1answer
33 views
Summing up elements of nested lists based on conditions from another list
Here is a simplified version of my question, nothing that I have a much larger dataset.
I have a list of samples of proportions:
...
4
votes
2answers
189 views
List of lists elementwise greater/smaller than
I have two lists
a = {{3,1,2},{5,1,3},{4,1,1}}
b = {{4,0,3},{4,2,2},{5,0,2}}
And would like to compare each element within
...
1
vote
3answers
56 views
Mapping a function with levelspec vs. Mapping over a flattened list
I have borrowed the following cyclic permutations list making function from here.
...
0
votes
1answer
80 views
Arrays, Mapping, and Convolutions
I'm trying to create a function that convolutes a 3D Normal Distribution to the points listed below. However, I think I'm going about it in the wrong way.
When I try and convolve it with the points, ...
1
vote
1answer
50 views
Replace second derivative with product rule
Suppose that after some calculations, I find
a[x]*D[g[x],x,x]+b[x]*D[h[x],x,x]+c[x]*D[j[x],x]
What sort of operations do I need to do in Mathematica such that ...
1
vote
1answer
28 views
Mapping the FindMinimum function over a matrix
I'm quite new to Mathematica and so still trying to work out how to use some of its syntax and functions. I have a function for the free energy of a generic system with two order parameters. I am then ...
0
votes
1answer
27 views
1
vote
2answers
76 views
How can I iterate across a list of triples?
i just started to use Mathematica and I`m completely new to programming. So i'm some kind of noob in the purest form..
I'm trying to transform a coordinate system into a different one. I'm using <...
6
votes
1answer
68 views
How to properly Abort from within a ParallelMap?
If a condition is met within a sub-kernel in the function being mapped, how does one cancel the whole ParallelMap operation?
...
0
votes
1answer
47 views
Using elements of list to solve a differential equation
I have created a list as shown in picture.
the digits inside f are values of a and q respectively.
I want to solve the Mathieu equation.....
2
votes
0answers
31 views
Map a function at the lowest level [closed]
How do I map a function to the lowest level of any given nested list? As an example, how do I create output from input in the ...
2
votes
1answer
69 views
Fast and Listable Piecewise function
I am writing a simulation where I have an array with ten columns and on the order of millions of rows, for which I need to iterate on the order of ten thousand times, making computation time a major ...
0
votes
0answers
30 views
Help with weird behaviour of Map[Take… on large lists
Lets say I create a giant list:
tmp=RandomReal[{1,10},600000000];
Now I want to take 10 random sublists of length 150000:
...
4
votes
1answer
142 views
Apply Max to each element of a list [duplicate]
I have a list
a = {1, 8, 0, 6, 5, 3, 5, 2, 2, 5}
I want to generate a new list whose elements are the same of a if it's bigger than 5, or 5 elsewhere.
I managed ...
2
votes
1answer
115 views
How to compute Maximum Drawdown faster and highlight data-list-line on the plot?
Given a list as
...
1
vote
2answers
71 views
How to caculate Position Cost Price in given trading list quickly?
Given a simulated trading list as
...
0
votes
1answer
23 views
Table of convolutes
Inputs
Start with a vector $x\in\mathbb{R}^{n}$, and a vector-valued function $f:\mathbb{R}^{n}\mapsto\mathbb{R}^{n}$.
Output
Given some $k\in\mathbb{Z}^{+}$, what are elegant ways to produce the ...
10
votes
1answer
98 views
Parallelize[MapIndexed[…,Association[…]]] returns broken result
Bug introduced in 10.0.2 or earlier and persisting through 12.0
Confirmed: CASE:4041910
Consider the following example:
...
1
vote
1answer
50 views
Mapping over a piecewise function
This is a followup to a question I posted earlier today. Suppose you have a piecewise function such as "snap=max[x,0]= x if x>0, 0 otherwise".
Then you would think that it must be straightworward to ...
0
votes
0answers
51 views
Using Map function with NDSolve
I would like to solve a set of differential equations but vary one parameter, KieP, between 900 and 1100.
The solution for a given parameter has many peaks. I would then like to interpolate between ...
0
votes
1answer
52 views
How to map a function to a specfic level spec
I'm rewriting a function into a manipulatable graphic and while I'm happily surprised with how concise functional programming can be, I'm having trouble mapping the anonymous function ...
13
votes
2answers
469 views
Project map to a particular shape
I want to project a map to a particular shape, like a circle or ellipse. For example, let's imagine we want to project a map of the continental United states so that its outline is that of a circle. ...
0
votes
0answers
93 views
Operation on sublists with multiple arguments
I have a list and add only the values which are > 0 with:
Total[Cases[mylist, x_ /; x > 0]]
How to do this if I now have a list of sublists?
...
1
vote
0answers
72 views
Run function as loop over two matrices
I'm still wrapping my head around Mathematica syntax. I have a matrix clustersAll that looks like
...
1
vote
0answers
83 views
0
votes
0answers
83 views
How to give a function multiple variables in a mapped and nested list?
I come from python (not advanced tho), and have been learning mathematica. I'm currently struggling with the following code:
This is a basic version of what i wanted to implement:
...
3
votes
4answers
169 views
@ and Sequence ( and /@ ) [duplicate]
list = { {a,b}, {c,d}, {e,g} }
How to efficiently get
{ f[a,b], f[c,d], f[e,g] }
I tried various combinations using ...
2
votes
2answers
134 views
Clear variables inside Module
I have a function that uses Module. The function takes as input a .csv that can have as many columns as it wishes to, and it ...
3
votes
1answer
53 views
Can I Use a List To Position An Arbitrary Number of Graphic Objects?
I can use a function to compute the positions of individual nodes of a neural network based on how many there are in each layer (nodesPerLayerList below). Now I want to display them all in position. ...
6
votes
2answers
259 views
Applying functions to lists
I have a few expressions $f(\theta,x)$, $g(\theta,x)$, $h(\theta,x)$ in terms of two variables, an angle and a length. The angle goes from $-\pi/2$ to $\pi/2$ and the length from 200 to 1500. This is ...
0
votes
2answers
114 views
Mapping slots over lists
In the meantime I'm accustomed to write special character orgies like D[%,#]&/@L (to quickly fish out the coefficients of the last input with respect to ...
1
vote
0answers
27 views
Color filling by GDP in a map
I would like to have a tool where one can type in a minimum GDP level and then every country that has this minimum level gets filled with color.
1
vote
2answers
67 views
How to I use Map to apply a defined function to a list?
Problem: How to map a function onto a list.
My (example input:
mylist = {{1, 2}, {3, 4}}
gg[x_, y_] := {N[x + y], N[x y]}
Map[gg, mylist]
Expected output:
...
1
vote
1answer
61 views
Angle between one vector and a list of vectors [closed]
I have one vector v1 and one list of vectors v2. I want to find the angle between them (see below):
...
8
votes
1answer
120 views
How to Parallelize a simple MapAt?
I have a simple map I would like to parallelize (4x speedup for my 4 cores):
...
2
votes
1answer
75 views
Extracting the graph of Keys in nested Associations
Related to this q: Extract all Values from nested Association
How to extract the direct graph of all Keys in nested Associations...
0
votes
2answers
61 views
13
votes
3answers
306 views
MapThread Not Mapping on Ragged Array
Update: WRI Support has considered this a missing feature of MapThread instead of a bug. A request to update MapThread to ...
1
vote
1answer
83 views
Removing outer concentric circle picked up by ComponentMeasurement
So I have performed EdgeDetect and ComponentMeasurements on my images and obtained a pretty good elliptical fit. However, the black shadow of the beads in the image is being picked up by ...
2
votes
0answers
43 views
Error when using Map in Pure Function [closed]
I'm trying to solve Project Euler 21
My solution is as follows:
...
4
votes
2answers
237 views
Setting each “curve” on a 3D plot to be of different colour similar to that of its 2D plot
Consider the functions
...
2
votes
0answers
34 views
Apply all possible permutations into a function [duplicate]
I need to create a function that returns all possible trebles of integers that sum up to a given number. For example, is n=2 then I need something like this:
...
9
votes
5answers
864 views
3
votes
1answer
147 views
Mapping multiple function on list [duplicate]
I know what you may be thinking so I use the code below to demonstrate what I intend to do.
...
1
vote
0answers
43 views
Coverting a list of products to a list of strings
I am trying to find a way of converting a product of variables to a string, eg. if I have abc... I wish to obtain "abc...". I ...
1
vote
1answer
83 views
Pause when mapping [closed]
I am mapping a function across a list, but would like to pause before each item.
For instance:
function[variable_]:=(
variable * 2
)
function/@{1,2,3}
would give ...
0
votes
0answers
76 views
Variables defined modulo $\pi$ and avoiding singularities; phase plotting for a map
I have the following $2$-dimensional implicitly defined map
...
4
votes
1answer
177 views
Apply a function to a list that is a subset of sublists
My MMA fu is very stale, and I don't seem to be able to see a simple way to apply a function across a subset of a list.
Specifically in the following data, I want to apply ...
1
vote
2answers
174 views
Comparing elements in a list of lists
I'm stuck with yet another list question.
The basic gist:
I have lists within a list like so:
...
