I'm trying to plot with image using gnuplot but it always returns me "Reading ras files from sequential devices not supported". Think of a file named "test.txt" includes:
6 5 4 3 1 0
3 2 2 0 0 1
0 0 0 0 1 0
0 0 0 0 2 3
0 0 1 2 4 3
0 1 2 3 4 5
Using gnuplot:
gnuplot> plot "test.txt" matrix w image
gnuplot> Reading ras files from sequential devices not supported
Reading ras files from sequential devices not supported
What can I do about it? Is there any software that I haven't installed in my computer?
I'm using openSuse and I'm not very familiar with it yet.
Thank you in advance
Related
I get a Maya .ma file, I want to understand the parameters for nurbsCurve, the file has contents like this:
createNode nurbsCurve; # create a nurbsCurve
setAttr -k off ".v"; # set attribute about knots?
setAttr ".cc" -type "nurbsCurve" # attribute setting
3 1 0 no 3
6 0 0 0 1 1 1
4 # 4 stand for the below has 4 coordiniates
7.82436 0.545707 8.54539
7.86896 0.545707 9.61357
7.28368 0.53563 9.8433
6.06638 0.53563 9.89412
;
...
I don't understand what the line 3 1 0 no 3 and 6 0 0 0 1 1 1 stands for, anybody understand what these lines stand for?
Here's what I know so far, only the first three figures.
[3] [1] [0]
corresponds to:
[degree] [span] [index of the form: open/closed/periodic]
I am trying to parse a VTK file in C by extracting its point data and storing each point in a 3D array. However, the file I am working with has 9 shorts per point and I am having difficulty understanding what each number means.
I believe I understand most of the header information (please correct me if I have misunderstood):
ASCII: Type of file (ASCII or Binary)
DATASET: Type of dataset
DIMENSIONS: dims of voxels (x,y,z)
SPACING: Volume of each voxel (w,h,d)
ORIGIN: Unsure
POINT DATA: Total number of points/voxels (dimx.dimy.dimz)
I have looked at the documentation and I am still not getting an understanding on how to interpret the data. Could someone please help me understand or point me to some helpful resources
# vtk DataFile Version 3.0
vtk output
ASCII
DATASET STRUCTURED_POINTS
DIMENSIONS 256 256 130
SPACING 1 1 1.3
ORIGIN 86.6449 -133.929 116.786
POINT_DATA 8519680
SCALARS scalars short
LOOKUP_TABLE default
0 0 0 0 0 0 0 0 0
0 0 7 2 4 5 3 3 4
4 5 5 1 7 7 1 1 2
1 6 4 3 3 1 0 4 2
2 3 2 4 2 2 0 2 6
...
thanks.
You are correct regarding the meaning of fields in the header.
ORIGIN corresponds to the coordinates of the 0-0-0 corner of the grid.
An example of a DATASET STRUCTURED_POINTS can be found in the documentation.
Starting from this, here is a small file with 6 shorts per point. Each line represents a point.
# vtk DataFile Version 2.0
Volume example
ASCII
DATASET STRUCTURED_POINTS
DIMENSIONS 3 4 2
ASPECT_RATIO 1 1 1
ORIGIN 0 0 0
POINT_DATA 24
SCALARS volume_scalars char 6
LOOKUP_TABLE default
0 1 2 3 4 5
1 1 2 3 4 5
2 1 2 3 4 5
0 2 2 3 4 5
1 2 2 3 4 5
2 2 2 3 4 5
0 3 2 8 9 10
1 3 2 8 9 10
2 3 2 8 9 10
0 4 2 8 9 10
1 4 2 8 9 10
2 4 2 8 9 10
0 1 3 18 19 20
1 1 3 18 19 20
2 1 3 18 19 20
0 2 3 18 19 20
1 2 3 18 19 20
2 2 3 18 19 20
0 3 3 24 25 26
1 3 3 24 25 26
2 3 3 24 25 26
0 4 3 24 25 26
1 4 3 24 25 26
2 4 3 24 25 26
The 3 first fields may be displayed to understand the data layout : x change faster than y, which change faster than z in file.
If you wish to store the data in an array a[2][4][3][6], just read while doing a loop :
for(k=0;k<2;k++){ //z loop
for(j=0;j<4;j++){ //y loop : y change faster than z
for(i=0;i<3;i++){ //x loop : x change faster than y
for(l=0;l<6;l++){
fscanf(file,"%d",&a[k][j][i][l]);
}
}
}
}
To read the header, fscanf() may be used as well :
int sizex,sizey,sizez;
char headerpart[100];
fscanf(file,"%s",headerpart);
if(strcmp(headerpart,"DIMENSIONS")==0){
fscanf(file,"%d%d%d",&sizex,&sizey,&sizez);
}
Note than fscanf() need the pointer to the data (&sizex, not sizex). A string being a pointer to an array of char terminated by \0, "%s",headerpart works fine. It can be replaced by "%s",&headerpart[0]. The function strcmp() compares two strings, and return 0 if strings are identical.
As your grid seems large, smaller files can be obtained using the BINARY kind instead of ASCII, but watch for endianess as specified here.
actual problem is like this which I got from an Online competition. I solved it but my solution, which is in C, couldn't produce answer in time for large numbers. I need to solve it in C.
Given below is a word from the English dictionary arranged as a matrix:
MATHE
ATHEM
THEMA
HEMAT
EMATI
MATIC
ATICS
Tracing the matrix is starting from the top left position and at each step move either RIGHT or DOWN, to reach the bottom right of the matrix. It is assured that any such tracing generates the same word. How many such tracings can be possible for a given word of length m+n-1 written as a matrix of size m * n?
1 ≤ m,n ≤ 10^6
I have to print the number of ways S the word can be traced as explained in the problem statement. If the number is larger than 10^9+7, I have to print S mod (10^9 + 7).
In the testcases, m and n can be very large.
Imagine traversing the matrix, whatever path you choose you need to take exatcly n+m-2 steps to make the word, among of which n-1 are down and m-1 are to the right, their order may change but the numbers n-1 and m-1 remain same. So the problem got reduced to only select n-1 positions out of n+m-2, so the answer is
C(n+m-2,n-1)=C(n+m-2,m-1)
How to calculate C(n,r) for this problem:
You must be knowing how to multiply two numbers in modular arithmetics, i.e.
(a*b)%mod=(a%mod*b%mod)%mod,
now to calculate C(n,r) you also need to divide, but division in modular arithmetic can be performed by using modular multiplicative inverse of the number i.e.
((a)*(a^-1))%mod=1
Ofcourse a^-1 in modular arithmetic need not equal to 1/a, and can be computed using Extended Euclidean Algorithm, as in your case mod is a prime number therefore
(a^(-1))=a^(mod-2)%mod
a^(mod-2) can be computed efficiently using repetitive squaring method.
I would suggest a dynamic programming approach for this problem since calculation of factorials of large numbers shall involve a lot of time, especially since you have multiple queries.
Starting from a small matrix (say 2x1), keep finding solutions for bigger matrices. Note that this solution works since in finding the solution for bigger matrix, you can use the value calculated for smaller matrices and speed up your calculation.
The complexity of the above soltion IMO is polynomial in M and N for an MxN matrix.
Use Laplace's triangle, incorrectly named also "binomial"
1 0 0 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
1 1 0 0 0
1 0 0 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
1 1 1 0 0
1 2 0 0 0
1 0 0 0 0
0 0 0 0 0
0 0 0 0 0
1 1 1 1 0
1 2 3 0 0
1 3 0 0 0
1 0 0 0 0
0 0 0 0 0
1 1 1 1 1
1 2 3 4 0
1 3 6 0 0
1 4 0 0 0
1 0 0 0 0
1 1 1 1 1
1 2 3 4 5
1 3 6 10 0
1 4 10 0 0
1 5 0 0 0
1 1 1 1 1
1 2 3 4 5
1 3 6 10 15
1 4 10 20 0
1 5 15 0 0
1 1 1 1 1
1 2 3 4 5
1 3 6 10 15
1 4 10 20 35
1 5 15 35 0
1 1 1 1 1
1 2 3 4 5
1 3 6 10 15
1 4 10 20 35
1 5 15 35 70
Got it? Notice, that elements could be counted as binomial members. The diag members are here: C^1_2, C^2_4,C^3_6,C^4_8, and so on. Choose which you need.
I have a large matrix of 1's and 0's, and am looking for a way to "fill" up areas that are locally dense with 1's.
I first did this task for an array, and counted the number of 1's within a certain radius of the element in questions. If the radius was 5, for example, and my threshold was 4, then a point that had 4 elements marked "1" within 5 elements to the left or right would be changed to a 1.
Basically I would like to generalized this to a two - dimensional array and have a resulting matrix that has "smooth" and "connected" regions of 1's and no "patchy" spots.
As an example, the matrix
1 0 0 1 0 0 0
0 0 1 0 1 0 0
0 1 0 1 0 0 0
0 0 1 1 1 0 0
would ideally be changed to
1 0 0 1 1 0 0
0 0 1 1 1 0 0
0 1 1 1 1 0 0
0 0 1 1 1 0 0
or something similar
For binary images, the morphologial operations that are implemented in MATLAB are perfect for manipulating the shape and size of connected regions. Specifically, the process of image closing is designed to fill holes in connected regions. In MATLAB, the function is imclose, which takes the image and a structuring element, similar to a filter kernel, for how neighboring pixels effect the filling of holes and gaps. A simple invocation of imclose is,
IM2 = imclose(IM,strel(ones(3)));
Larger gaps can be filled by increasing the area of the influence of of neighboring pixes, via larger structuring elements. For example, we an use a disk of radius 10 pixels:
IM2 = imclose(IM,strel('disk',10));
While, imclose supports grayscale and binary (0 and 1) images, the function bwmorph is designed for operation on binary images only but provides a generic interface to all of the morphological operations and various neat combinations of operations (e.g. 'bothat', 'tophat', etc.). The syntax for closing is simplified with bwmorph:
BW2 = bwmorph(BW,'close');
Here the structuring element is the standard ones(3).
A simple filter such as the following might do the trick:
h = [ 0 1 0
1 0 1
0 1 0];
img2=(imfilter(img,h)>2) | img;
For instance:
img =
1 0 0 1 0 0 0
0 0 1 0 1 0 0
0 1 0 1 0 0 0
0 0 1 1 1 0 0
img2 =
1 0 0 1 0 0 0
0 0 1 1 1 0 0
0 1 1 1 1 0 0
0 0 1 1 1 0 0
You can try different filters to modify the output img2.
This uses the image processing toolbox. If you don't have that, you may want to look up equivalent routines from the matlab exchange.
I am using MPI in C. I was able to distribute parts of an array to different processors. And the different processors did all the manipulation I wanted. Now I am at the point where I wanted to combine all the sub-arrays that are in all the processors into one big array. For example if the different processors had sub-arrrays as follows:
Processor 1:
0 1 1 0
0 0 1 0
Processor 2:
0 0 1 0
1 1 0 1
Processor 3:
1 1 0 0
1 1 1 1
...
I want to be able to combine, or "concatenate", all the sub-arrays together. For example I would want the large array to be:
0 1 1 0
0 0 1 0
0 0 1 0
1 1 0 1
1 1 0 0
1 1 1 1
...
I was trying to use MPI_Reduce but I couldn't find an operation to do what I wanted to do. Is there another MPI method I could use to achieve what I am looking for?
You are looking for MPI_Gather:
Each process (root process included) sends the contents of its send buffer to the root process. The root process receives the messages and stores them in rank order.
For documentation and examples, see here and here. The section 5.5 in the MPI 2.2 Standard also has examples.