How do i call a function that i just wrote in APL, passing in a matrix? I have already tried many things but I can't seem to find the solution. I would greatly appreciate any help.
I don't think this is a duplicate but please report if you find one :)
Thanks
Unless you declare otherwise, an APL function will accept any array as argument. For example, let's define a function which multiplies its argument by 2 and then adds 1:
∇ result←t2p1 argument
result←1+2×argument
∇
Now we define a 3-by-4 matrix of some numbers, and ask for its value:
matrix←3 4⍴3 1 4 1 5
matrix
3 1 4 1
5 3 1 4
1 5 3 1
Finally, we apply the function to the matrix:
t2p1 matrix
7 3 9 3
11 7 3 9
3 11 7 3
Related
Is there a good way in q to input somewhat large complicated nested dictionaries which represent/will be converted to json? I'm trying to control the echarts javascript library which basically just renders charts based on json config options. What I'm doing now is:
opt.title.text:"my chart"
opt.xAxis.data:til 100
opt.series.data:100?5
opt.series.type:`line
toClient[opt] /serializes and sends to browser
but is there an obvious way to get rid of the intermediate assignment? Is making a function to take key-path/value pairs and turn them into a dictionary the way to go or is there a better way to go about this?
Or is this something that should be avoided in q, and instead just manually set write q to set specific options and handle the json object map in the javascript client?
Not sure if this is really what you are looking for, but you can create the nested dictionary structure directly if that's what you're after?
q)`title`xAxis`series!(enlist[`text]!enlist"my chart";enlist[`data]!enlist til 100;`data`type!(100?5;`line))
title | (,`text)!,"my chart"
xAxis | (,`data)!,0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 ..
series| `data`type!(0 1 1 3 3 3 2 2 4 1 3 3 1 4 0 4 4 4 2 4 3 3 4 0 4 0 0 1 0..
Consider a function F[x;y] that generates a table. I also have two lists; xList:[x1;x2;x3] and yList:[y1;y2;y3]. What is the best way to do a simple comma join of F[x1;y1],F[x1;y2],F[x1;y3],F[x2;y1],..., thereby producing one large table?
You have asked for the cross product of your argument lists, so the correct answer is
raze F ./: xList cross yList
Depending on what you are doing, you might want to look into having your function operate on the entire list of x and the entire list of y and return a table, rather than on each pair and then return a list of tables which has to get razed. The performance impact can be considerable, for example see below
q)g:{x?y} //your core operation
q)//this takes each pair of x,y, performs an operation and returns a table for each
q)//which must then be flattened with raze
q)fm:{flip `x`y`res!(x;y; enlist g[x;y])}
q)//this takes all x, y at once and returns one table
q)f:{flip `x`y`res!(x;y;g'[x;y])}
q)//let's set a seed to compare answers
q)\S 1
q)\ts do[10000;rm:raze fm'[x;y]]
76 2400j
q)\S 1
q)\ts do[10000;r:f[x;y]]
22 2176j
q)rm~r
1b
Setup our example
q)f:{([] total:enlist x+y; x:enlist x; y:enlist y)}
q)x:1 2 3
q)y:4 5 6
Demonstrate F[x1;y1]
q)f[1;4]
total x y
---------
5 1 4
q)f[2;5]
total x y
---------
7 2 5
Use the multi-valent apply operator together with each' to apply to each pair of arguments.
q)raze .'[f;flip (x;y)]
total x y
---------
5 1 4
7 2 5
9 3 6
Another way to achieve it using each-both :
x: 1 2 3
y: 4 5 6
f:{x+y}
f2:{ a:flip x cross y ; f'[a 0;a 1] }
f2[x;y]
5j, 6j, 7j, 6j, 7j, 8j, 7j, 8j, 9j
I am working on NGSim Traffic data, having 18 columns and 1180598 rows in a text file. I want to smooth the position data, in the column 'Local Y'. I know there are built-in functions for data smoothing in R but none of them seem to match with the formula I am required to apply. The data in text file looks something like this:
Index VehicleID Total_Frames Local Y
1 2 5 35.381
2 2 5 39.381
3 2 5 43.381
4 2 5 47.38
5 2 5 51.381
6 4 8 504.828
7 4 8 508.325
8 4 8 512.841
9 4 8 516.338
10 4 8 520.854
11 4 8 524.592
12 4 8 528.682
13 4 8 532.901
14 5 7 39.154
15 5 7 43.153
16 5 7 47.154
17 5 7 51.154
18 5 7 55.153
19 5 7 59.154
20 5 7 63.154
The above data columns are just example taken out of original file. Here you can see 3 vehicles, with vehicle IDs = 2, 4 and 5 but in fact there are 2169 vehicles with different IDS. The column Total_Frames tell us how many times vehicle Id of each vehicle is repeated in the first column, for example in the table above, vehicle ID 2 is repeated 5 times, hence '5' in Total_Frames column. Following is the formula I am required to apply to remove data noise (smoothing) from column 'Local Y':
Smoothed Position Value = (1/(Summation of [EXP^-abs(i-k)/delta] from k=i-D to i+D)) * ( (Summation of (Local Y) *[EXP^-abs(i-k)/delta] from k=i-D to i+D))
where,
i = index #
delta = 5
D = 15
I have tried using the built-in functions, which I know of, but they don't smooth the data as required. My question is: Is there any built-in function in R which can do the data smoothing in the way of given formula or which could take this formula as an argument? I need to apply the formula to every value in Local Y which has 15 values before and 15 values after them (i-D and i+D) for same vehicle Id. Can anyone give me any idea how to approach the problem? Thanks in advance.
You can place your formula in a function and then use the apply function of R to apply it to the elements in your "Local Y" column of the dataframe
I've following problem and don't know the terminology to describe it and hence search for possible solutions.
I have a pivot table (matrix), eg each row and column have a named header. there is a defined set for rows and columns. Now let's assume that 10 rows are "combined" meaning each column is summed up to create a new "pattern".
What I would like is a way to determine alternative row combinations that lead to the same or similar "combined" pattern.
1 1 1
5 5 5
"Combined"
6 6 6
alternate row combination:
2 2 2
4 4 4
Suggestions? How is this problem called?
http://en.wikipedia.org/wiki/System_of_linear_equations#Matrix_equation
I just have to transpose above matrix to get Matrix A
[code]
1 5
1 5
1 5
[/code]
combined matrix is a vector b:
[code]
6
6
6
[/code]
and x would be just a vector full of 1.
I have a txt file which contains a set of 3 Dimensional data points and I would like to create a vtkPolyData based on those points.
In the file, I have the number of points on the first line, in my case they are 6 x 6. And after that the actual coordinates of each point. The content of the file is like this.
6 6
1 1 3
2 1 3.4
3 1 3.6
4 1 3.6
5 1 3.4
6 1 3
1 2 3
2 2 3.8
3 2 4.2
4 2 4.2
5 2 3.8
6 2 3
1 3 3
2 3 3
3 3 3
4 3 3
5 3 3
6 3 3
1 4 3
2 4 3
3 4 3
4 4 3
5 4 3
6 4 3
1 5 3
2 5 3.8
3 5 4.2
4 5 4.2
5 5 3.8
6 5 3
1 6 3
2 6 3.4
3 6 3.6
4 6 3.6
5 6 3.4
6 6 3
How can I build a vtkPolyData structure with a txt file with this data?
It looks to me like you have a regularly gridded series of points, right? If so, vtkImageData might be a better choice. You can always use a geometry filter afterwards to convert to polydata if you really need it that way.
Create a vtkImageData instance.
Set its dimensions to (6, 6, 1) (the third dimension is ignored).
Set its data type to an appropriate type (float or double, I guess).
Call AllocateScalars();
If in C++,
call GetScalarPointer() and cast it to the data type set in 3.
This pointer will point to an array of size 36. You can just fill each point as you would normally.
If in another language (TCL/Python/Java), call SetScalarComponentFromFloat on the image data, with the arguments (x, y, 0, 0, value). The first 0 is the 3rd dimension and the second is for the first component.
This will give you a grid, and it'll be far more memory efficient than a polydata.
If you want to visualize only the points, use a vtkDataSetMapper, and setup the actor's property with SetRepresentationToPoints(), setting an appropriate point size. That will do a simple job of visualization.
Are these examples useful? In particular, this does generation of points and polygons, so it should be possible to adapt. The core seems to be (with lots left out):
# ...
vtkPolyData shell
vtkFloatPoints points
vtkCellArray strips
# Generate points...
loop {
...
points InsertPoint $k $x0 $x1 $x2
}
shell SetPoints points
points Delete
# Generate triangles/polygons...
loop {
strips InsertNextCell $NP2
# ...
strips InsertCellPoint [expr $kb +$ke ]
# ...
strips InsertCellPoint [expr $kb +$ke ]
}
shell SetStrips strips
strips Delete
# ...