Linked Questions

521
votes
19answers
129k views

Where can I find examples of good Mathematica programming practice?

I consider myself a pretty good Mathematica programmer, but I'm always looking out for ways to either improve my way of doing things in Mathematica, or to see if there's something nifty that I haven't ...
96
votes
4answers
5k views

Flatten command: matrix as second argument

One thing I could never wrap my head around is how Flatten works when provided with a matrix as the second argument, and the Mathematica help isn't particularly ...
22
votes
5answers
1k views

MapThread over sublists of different length

I have a list which looks like this: l={{1,0,3,4},{0,2},{0,0,1,3},{1,2,0}}. Now I would like to count how many 0s the sublists contain in the first, second,... slot....
14
votes
3answers
3k views

How to add lists with unequal length?

Given lists of unequal lengths, I want to add them together element-wise, treating missing elements as zero. For example, {1, 2, 3} + {a, b} + {x} should give ...
11
votes
2answers
6k views

How to get MATLAB data imported with the same dimensions?

I have some MATLAB image data with the following dimensions (output is from MATLAB): >> size(im) ans = 86 86 3 45 The data imports just fine ...
9
votes
6answers
286 views

Is there a better way to add a “key” for the list of GatherBy?

In ruby , 1.upto(10).to_a.group_by{|x| x%3} gives {1=>[1, 4, 7, 10], 2=>[2, 5, 8], 0=>[3, 6, 9]} I would like use ...
9
votes
3answers
886 views

Operations on elements of ragged lists

Suppose I have a list of lists with different lengths, sorted from longest to shortest ...
2
votes
3answers
937 views

How to transpose unequal lists

As the titel says I want to transpose a matrix containing rows of unequal length, to be able to transport them to excel (in row form, there are too many datapoint to write them in a cell. In another ...
8
votes
3answers
263 views

How can I generate a $2n$-point moving maximum of a list as efficiently as MaxFilter?

This is based on the prior question, Moving maximum function?, where @rasher provided two winning solutions (i.e. clearly the most efficient): MaxFilter[list, 1] ...
2
votes
3answers
2k views

Plot a table of lists

I want to make a point plot of a table with lists in it. Assume I have data like this: data={{1,2,3,4},{5,6},{1,5},{2,4}}; and now I want to make a point plot ...
5
votes
3answers
255 views

Manipulating list with sub-lists of different lengths

Consider the following list, which is composed of sublists with different lengths ...
9
votes
3answers
233 views

Threading elements over corresponding elements in the second list

I often need to merge two lists like the following: $A=\{\{0.1\},\{0.2\},\ldots,\{1\}\}$ $B=\{\{x_1\},\{x_{21},x_{22},x_{23}\},\{x_{31},x_{32},x_{33}\},\ldots,x_N\}$ in a way to ideally obtain a ...
2
votes
1answer
103 views

Efficient creation of lists from other lists

Given the following lists: v1 = {a, c, e}; v2 = {b, d, f}; how does one efficiently create the following "combination lists"? ...
1
vote
1answer
277 views

Transpose a ragged triangular matrix and display as columns rather than rows

I have a triangular list of lists as follows: ...