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I'm trying to figure out how to pull a number from a cell and check if it's positive or negative and then from there do one of 2 equations to produce a final number. This is my code, but it doesn't work because the equations become strings. Not sure if there is a simple solution or if it requires a script of some sort since Google Sheets doesn't have an EVALUATE function.
=(CONCATENATE(IF(AC2>=0,"100 / (AC2 + 100) * 100","(AC2*-1)/ ((AC2*-1)+100) * 100)"),"%"))
Edit:
Final Code:
=CONCATENATE(IF(AC2>=0,ROUND(100/(AC2+100)*100, 0),ROUND((AC2*-1)/((AC2*-1)+100)*100, 0)),"%")
Remove the quotes around your equations so it looks more like..
=IF(AC2>=0,100/(AC2+100)*100,(AC2*-1)/((AC2*-1)+100)*100)
Any reason you are concatenating a %? Perhaps you just want to format it as a percentage.
I am working on a Dataset object with one column, named Property.
The data is given as shown in the following picture:
Based on the range, I would like to assign a new value, and eventually replace the whole column in question. For example if the range is 500-5000, I would like to get the value 1, and for 5000-50000, I would like to give the value 2, and so on.
As I understand it, you want to recode one column of a dataset by modifying the dataset. To my knowledge, datasets are not really designed to be mutable types. If you can accept that, here are two ways to proceed.
First, let's get some artifical data.
ds = Dataset[<|"x" -> RandomInteger[10],
"y" -> Interval[{10^#, 10^(# + 1)}]|> & /# Range[5]]
Now suppose we want to recode the second column with a function f:
ds[All, {2 -> f}]
Note that the original dataset is unchanged. (Usually a good thing.)
Here's an example function to try out.
f[x_Interval] := Log[10, x[[1, 1]]]
ds[All, {2 -> f}]
Now a big problem with this is that your new dataset has a column with exactly the same name but entirely different interpretation. If this bothers you, you can instead append to the dataset with a new name.
Append[#, "y2" -> f[#y]] & /# ds
Edit:
What about those dollar signs? Unless you show us the full form of an entry, I'll have to guess. So I'll guess that the following artificial data gets us close enough to be useful:
ds = Dataset[<|"x" -> RandomInteger[10],
"y" -> Quantity[Interval[{10^#, 10^(# + 1)}], "USDollars"]|> & /# Range[5]]
This just means we need to make a small change in f:
f[Quantity[Interval[{x_, _}], _]] := Log[10, x]
Then we can replace or append as before:
ds[All, {2 -> f}]
Append[#, "y2" -> f[#y]] & /# ds
If we have grid stuff with column integer x (starting from 1 as we are in mathematica) named "Property", the code to get the column of transformed ranges in x -- to what I think want you -- is below:
Replace[#1[[1]] & /# stuff, x_ :> IntegerLength[x[[1, 1]]] - 2, {1}]
It takes all the ranges in the specified column, and subtracts 2 from the length of the lower part of the range to give you your result.
For example, if we take your sample ranges:
stuff = {{$Interval[{500, 50000}], things, things},
{$Interval[{5000, 5000000}], things, things}}
And run it through our Replace:
Replace[#1[[1]] & /# stuff, x_ :> IntegerLength[x[[1, 1]]] - 2, {1}]
We get an Out: of:
{1, 2}
You can then easily modify the Replace above to give you the transformed column in situ of stuff.
I've been using the Accelerate framework to do some audio signal processing and I've been using the vDSP_conv function to perform some cross-correlations. Usually, the values returned look like this (left column is the array index, and right column is the value of the array at that index after being returned from vDSP_conv):
125001 1.576556
125002 1.523622
125003 1.439102
125004 1.593097
125005 1.171977
125006 0.020228
125007 -0.988876
125008 -1.526720
125009 -1.056652
125010 -0.181521
125011 -0.029592
125012 0.077848
125013 0.319371
125014 0.080034
125015 -0.629983
But sometimes the results look like this, for no discernible reason:
125001 65531903404620711577128764702720.000000
125002 271523249688835947415863891591168.000000
125003 253191001846134141440285462233088.000000
125004 197376212065818453160643396632576.000000
125005 247836891833411757917279954665472.000000
125006 203601464352748581549908776976384.000000
125007 193256115501319341596977567629312.000000
125008 55431884287617507551879029063680.000000
125009 -242471930502532513482802284462080.000000
125010 -259877560883016098488551924039680.000000
125011 -201496656800953613737511541014528.000000
125012 -240627419186810410707269384667136.000000
125013 -241660441463967832878539113234432.000000
125014 -169626548145197368918504628027392.000000
125015 -157041504634723839288379166425088.000000
I ran the program again after getting these results, and they went back to the original (correct) results. Has anyone else experienced this or have any ideas as to why it's happening?
Probably this is some overflow effect in one of the vectors you are correlating. As the specs say "The length of this vector must be at least N + P - 1." So e.g. if you are doing autocorrelation of vector A of length n, you should first create a vector of length 2*n (say A_extended), copy A into that, and do
vDSP_conv(A_extended, 1, A, 1, &result, 1, n, n)
I'm trying to iterate over 2 parameters to get two splines for each pair. The code:
y_arr:[0.2487,0.40323333333333,0.55776666666667,0.7123]$
str_h_arr:[-0.8,-1.0,-1.2,-1.4]$
z_points:[0,0.1225,0.245,0.3675,0.49,0.6125,0.735,0.8575,0.98,1.1025,1.225,1.3475,1.47,
1.5925,1.715,1.8375,1.96,2.0825,2.205,2.26625,2.3275,2.3765,2.401,2.4255,2.43775,
2.4451,2.448775,2.45]$
length(a)$
length(b)$
load(interpol)$
for y_k:1 thru length(a) do (
for h_k:1 thru length(b) do (
y:y_arr[y_k],
str_h:str_h_arr[h_k],
bot_startpoints: [[-2.45,0],[0,y],[2.45,0]],
top_startpoints: [[-2.45,str_h_min],[0,y+str_h],[2.45,str_h_min]],
spline: cspline(bot_startpoints),
bot(x):=''spline,
print(bot(0))
)
);
//Part with top spline is skipped.
For all iterations output is now the same: 0.7123
What I want to get is two splines like in picture
Members of y_arr are y values in x=0, str_h_arr: height between splines in x=0.
So bot(0) should give me all values from y_arr.
If i don't use loop and just give this block values of y_k and h_k, it's working properly.
Can anybody point me to where I'm (or Maxima is) wrong with using loop with cspline?
The problem is that quote-quote (two single quotes, '') is applied only once, when it is read in input; it is not applied every time the expression in evaluated in the loop.
Looks like you need only to evaluate the spline at x = 0 and nothing else. So I'll suggest ev(spline, x=0) to evaluate it. You can also construct a lambda expression and evaluate that.
Here is the program after I've revised it as described above. Also, it is simpler and clearer to write for y in y_arr do (...) rather than making use of an explicit index for y_arr.
y_arr:[0.2487,0.40323333333333,0.55776666666667,0.7123]$
str_h_arr:[-0.8,-1.0,-1.2,-1.4]$
z_points:[0,0.1225,0.245,0.3675,0.49,0.6125,0.735,0.8575,0.98,1.1025,1.225,1.3475,1.47,
1.5925,1.715,1.8375,1.96,2.0825,2.205,2.26625,2.3275,2.3765,2.401,2.4255,2.43775,
2.4451,2.448775,2.45]$
load(interpol)$
for y in y_arr do (
for str_h in str_h_arr do (
bot_startpoints: [[-2.45,0],[0,y],[2.45,0]],
top_startpoints: [[-2.45,str_h_min],[0,y+str_h],[2.45,str_h_min]],
spline: cspline(bot_startpoints),
print (ev (spline, x=0))));
This is the output I get:
0.2487
0.2487
0.2487
0.2487
0.40323333333333
0.40323333333333
0.40323333333333
0.40323333333333
0.55776666666667
0.55776666666667
0.55776666666667
0.55776666666667
0.7123
0.7123
0.7123
0.7123
For example, if I want to read the middle value from magic(5), I can do so like this:
M = magic(5);
value = M(3,3);
to get value == 13. I'd like to be able to do something like one of these:
value = magic(5)(3,3);
value = (magic(5))(3,3);
to dispense with the intermediate variable. However, MATLAB complains about Unbalanced or unexpected parenthesis or bracket on the first parenthesis before the 3.
Is it possible to read values from an array/matrix without first assigning it to a variable?
It actually is possible to do what you want, but you have to use the functional form of the indexing operator. When you perform an indexing operation using (), you are actually making a call to the subsref function. So, even though you can't do this:
value = magic(5)(3, 3);
You can do this:
value = subsref(magic(5), struct('type', '()', 'subs', {{3, 3}}));
Ugly, but possible. ;)
In general, you just have to change the indexing step to a function call so you don't have two sets of parentheses immediately following one another. Another way to do this would be to define your own anonymous function to do the subscripted indexing. For example:
subindex = #(A, r, c) A(r, c); % An anonymous function for 2-D indexing
value = subindex(magic(5), 3, 3); % Use the function to index the matrix
However, when all is said and done the temporary local variable solution is much more readable, and definitely what I would suggest.
There was just good blog post on Loren on the Art of Matlab a couple days ago with a couple gems that might help. In particular, using helper functions like:
paren = #(x, varargin) x(varargin{:});
curly = #(x, varargin) x{varargin{:}};
where paren() can be used like
paren(magic(5), 3, 3);
would return
ans = 16
I would also surmise that this will be faster than gnovice's answer, but I haven't checked (Use the profiler!!!). That being said, you also have to include these function definitions somewhere. I personally have made them independent functions in my path, because they are super useful.
These functions and others are now available in the Functional Programming Constructs add-on which is available through the MATLAB Add-On Explorer or on the File Exchange.
How do you feel about using undocumented features:
>> builtin('_paren', magic(5), 3, 3) %# M(3,3)
ans =
13
or for cell arrays:
>> builtin('_brace', num2cell(magic(5)), 3, 3) %# C{3,3}
ans =
13
Just like magic :)
UPDATE:
Bad news, the above hack doesn't work anymore in R2015b! That's fine, it was undocumented functionality and we cannot rely on it as a supported feature :)
For those wondering where to find this type of thing, look in the folder fullfile(matlabroot,'bin','registry'). There's a bunch of XML files there that list all kinds of goodies. Be warned that calling some of these functions directly can easily crash your MATLAB session.
At least in MATLAB 2013a you can use getfield like:
a=rand(5);
getfield(a,{1,2}) % etc
to get the element at (1,2)
unfortunately syntax like magic(5)(3,3) is not supported by matlab. you need to use temporary intermediate variables. you can free up the memory after use, e.g.
tmp = magic(3);
myVar = tmp(3,3);
clear tmp
Note that if you compare running times with the standard way (asign the result and then access entries), they are exactly the same.
subs=#(M,i,j) M(i,j);
>> for nit=1:10;tic;subs(magic(100),1:10,1:10);tlap(nit)=toc;end;mean(tlap)
ans =
0.0103
>> for nit=1:10,tic;M=magic(100); M(1:10,1:10);tlap(nit)=toc;end;mean(tlap)
ans =
0.0101
To my opinion, the bottom line is : MATLAB does not have pointers, you have to live with it.
It could be more simple if you make a new function:
function [ element ] = getElem( matrix, index1, index2 )
element = matrix(index1, index2);
end
and then use it:
value = getElem(magic(5), 3, 3);
Your initial notation is the most concise way to do this:
M = magic(5); %create
value = M(3,3); % extract useful data
clear M; %free memory
If you are doing this in a loop you can just reassign M every time and ignore the clear statement as well.
To complement Amro's answer, you can use feval instead of builtin. There is no difference, really, unless you try to overload the operator function:
BUILTIN(...) is the same as FEVAL(...) except that it will call the
original built-in version of the function even if an overloaded one
exists (for this to work, you must never overload
BUILTIN).
>> feval('_paren', magic(5), 3, 3) % M(3,3)
ans =
13
>> feval('_brace', num2cell(magic(5)), 3, 3) % C{3,3}
ans =
13
What's interesting is that feval seems to be just a tiny bit quicker than builtin (by ~3.5%), at least in Matlab 2013b, which is weird given that feval needs to check if the function is overloaded, unlike builtin:
>> tic; for i=1:1e6, feval('_paren', magic(5), 3, 3); end; toc;
Elapsed time is 49.904117 seconds.
>> tic; for i=1:1e6, builtin('_paren', magic(5), 3, 3); end; toc;
Elapsed time is 51.485339 seconds.