Octave. Get the first element from array - octave

I have a matrix that looks like:
matrix =
106168 1457100277117478
106069 1457100277417227
111159 1457100277850577
24408 1457100278150562
I need to take the first element of the second column for my further calculation. But I failed to do that!
The piece of code for that is the following:
time = matrix(:, 2(1));
format long;
disp('!time = '); disp(time);
As a result I got:
!time =
1457100277117478
1457100277417227
1457100277850577
1457100278150562
I didn't use any loop :(
I would like to get only the first value, i.e., 1457100277117478.
What did I do in a wrong way?

Related

Plot on higher time frame. Security, mutable variable, global variable, function problem

I'm trying to plot the same shape from the 15 min onto the Daily as well. This is the code to plot a shape on the 15 min which works fine;
if crossover(s3K,s3D) and s3K<25 and (s4K-s4D<3 and s4K-s4D>-3) and s4K<35//or s4D-s4K>0 and s4D-s4K<1 and s4K<50 and s1K<40
rwCross:=true
plotshape(rwCross, style = shape.arrowup, location = location.belowbar, color=color.yellow, size=size.small)
But to plot it on the daily i've tried;
rwCrossDaily = security(syminfo.tickerid,'D', rwCross)
plotshape(rwCrossDaily, style = shape.arrowup, location = location.belowbar, color=color.yellow, size=size.small)
Which gives me the mutable variable error. So i tried using a function to get around it;
rwCross_func() =>
if crossover(s3K,s3D) and s3K<25 and (s4K-s4D<3 and s4K-s4D>-3) and s4K<35//or s4D-s4K>0 and s4D-s4K<1 and s4K<50 and s1K<40
rwCross:=true
rwCrossDaily = security(syminfo.tickerid,'D', rwCross_func())
But now it tells me I 'Cannot modify global variable 'rwCross' in function.'
Help please!
Best solution and cleanest solution here is to just make a bool out of your condition in its simplest form:
rwCross = crossover(s3K,s3D) and s3K<25 and (s4K-s4D<3 and s4K-s4D>-3) and s4K<35//or s4D-s4K>0 and s4D-s4K<1 and s4K<50 and s1K<40
rwCross will naturally become true without the if. This way we do not need to have anything mutable, although there are more solutions for situations that we must...
Cheers!

Use of function / return

I had the task to code the following:
Take a list of integers and returns the value of these numbers added up, but only if they are odd.
Example input: [1,5,3,2]
Output: 9
I did the code below and it worked perfectly.
numbers = [1,5,3,2]
print(numbers)
add_up_the_odds = []
for number in numbers:
if number % 2 == 1:
add_up_the_odds.append(number)
print(add_up_the_odds)
print(sum(add_up_the_odds))
Then I tried to re-code it using function definition / return:
def add_up_the_odds(numbers):
odds = []
for number in range(1,len(numbers)):
if number % 2 == 1:
odds.append(number)
return odds
numbers = [1,5,3,2]
print (sum(odds))
But I couldn’t make it working, anybody can help with that?
Note: I'm going to assume Python 3.x
It looks like you're defining your function, but never calling it.
When the interpreter finishes going through your function definition, the function is now there for you to use - but it never actually executes until you tell it to.
Between the last two lines in your code, you need to call add_up_the_odds() on your numbers array, and assign the result to the odds variable.
i.e. odds = add_up_the_odds(numbers)

Dimensional error when i try to read month number from file

I'm new to Octave and I am trying to read the month number of a datetime values in order to do a equation with it. The problem is every time I try to read it I get the same dimensional error and i don't know why...
Here is my code:
clear
clc
pkg load io
pkg load financial
[num,date] = xlsread('EMA_VR 2019.xlsx','A184:A215');
num=datenum(date);
DataString=datestr(date)
m= month(num,DataString)
The result is always this:
DataString =
01-Jul-2019
02-Jul-2019
03-Jul-2019
04-Jul-2019
05-Jul-2019
06-Jul-2019
07-Jul-2019
08-Jul-2019
09-Jul-2019
10-Jul-2019
11-Jul-2019
12-Jul-2019
13-Jul-2019
14-Jul-2019
15-Jul-2019
16-Jul-2019
17-Jul-2019
18-Jul-2019
19-Jul-2019
20-Jul-2019
21-Jul-2019
22-Jul-2019
23-Jul-2019
24-Jul-2019
25-Jul-2019
26-Jul-2019
27-Jul-2019
28-Jul-2019
29-Jul-2019
30-Jul-2019
31-Jul-2019
01-Aug-2019
error: horizontal dimensions mismatch (1x1 vs 32x1)
error: called from
month at line 40 column 7
Teste at line 13 column 2
Also, when I try to return the year or day it always gives me the right value, hope someone can help me, it would be very appreciated.
The month function can only handle 1x1 data. That's what your error is saying. Since your date vector is 32x1, you can't use that function the way you are doing.
However, you can use a for loop, and store the values in a vector:
[num,date] = xlsread('EMA_VR 2019.xlsx','A184:A215');
Month = zeros(size(num)); % Month will have the same dimensions as num
for i=1:length(Month) % Loops through the length of Month
Month(i) = month(num(i)); % Applies the month function to the i-th entry of num
end

error in reading csv file to plot graph

i am just not able to read a csv file .I want to display a graph for it.
I am getting error:
TypeError: n is undefined
please help me out!!
d3.csv("example.csv", function(dataset){
var svg=d3.select("body").append("svg").attr("width",w).attr("height",h);
var xScale=d3.scale.ordinal().domain(d3.range(dataset.length)).rangeRoundBands([0,w],0.05);
var yScale=d3.scale.linear().domain([0,d3.max(dataset.value)]).range([0,h]);
svg.selectAll("rect").data(dataset).enter().append("rect").attr({x:function(d,i) {return xScale(i);}, y:function(d){
return h-yScale(d);}, width:xScale.rangeBand(),height:function(d){return yScale(d);},fill:function(d){return "rgb(0,0,"+(d.value*10)+")";}});
d3.select("svg").selectAll("text").data(dataset).enter().append("text").text(function(d) {return d.value;}).attr("x",function(d,i){
return xScale(i)+xScale.rangeBand()/2;}).attr("y",function(d){return h-yScale(d)+14;}).attr("font-family","sans-serif").attr("font-size","10px").attr
("fill","white").attr("text-anchor","middle");
d3.select("p").on("click",function(){
var numValues=dataset.length;
dataset=[];
for(var i=0;i<numValues;i++)
{var newNumber=Math.floor(Math.random()*25);
dataset.push(newNumber,newNumber);
}
yScale.domain([0,d3.max(dataset)]);
svg.selectAll("rect").data(dataset).transition().delay(function(d,i){return i/dataset.length*1000;})
.duration(500).attr("y",function(d){return h-yScale(d); }).attr("height",function(d) {return yScale(d);}).attr("fill",function(d){
return "rgb(0,0,"+(d.value*10)+")";});
svg.selectAll("text").data(dataset).transition().delay(function(d,i){return i/dataset.length*1000;}).duration(500).text(function(d){return d.value;})
.attr("x",function(d,i){return xScale(i)+xScale.rangeBand()/2;}).attr("y",function(d) {return h-yScale(d)+14;})
.attr("font-family","sans-serif").attr("font- size","10px").attr("fill","white").attr("text-anchor","middle")
;});
});
here is my csv file
names,value
john,78
brad,105
amber,103
james,2
dean,74
pat,45
matt,6
andrew,18
ashley,15
As mentioned by cuckovic there are quite a few errors in your code, not to mention that you seem to be using different styles to achieve similar things which is confusing. Anyway there are 3 fundamental things that are casuing you trouble, the first is your dataset. The value column of the csv is being read as a string. You need to convert it to a number by:
dataset.forEach(function (d,i) {
d.value = +d.value;
});
The next issue you have is the yScale where you have set the range to .range([0,h]);. This is the wrong way round for an svg viewport in which the y direction starts from top and increases towards the bottom. So you need to swap the 0 and h around in the range.
The next thing to address is the difference between d and d.value. When you bind data through the data() operator you are generally binding an array. In this case it is an array of objects. So after you have bound the data, d refers to each element of that array which in this case is an object containing a name and a value. This can be seen if you console.log your dataset. When d is passed to yScale it doesn't know what to do with it as it is not a number, what you really want to do is to pass d.value to yScale. So replace your d's with d.value.
Finally, the last part of your code starting at d3.select("p") does not seem to add anything.
I'd recommend reading Scott Murray's tutorials, particularly this one if you haven't already.

Flex Number.toFixed not giving expected result

I have a function that gets a numeric value (as Object) and returns a well formatted representation of that number. Because we can get very small numbers, in the process we use the Number object of flex. this is part of the code:
var numericValue:Number = Number(value.toString());
var fixed:String = numericValue.toFixed(precision);
This is the problem: there are situations that the numeric value is in the form of
5.684341886080802e-14
because we want to represent these numbers as 0 we use the above code. In this specific case, where precision is 0 we get an odd result
Initial Values:
value = 5.684341886080802e-14
percision = 0
Operation on values:
var numericValue:Number = Number(value.toString());
var fixed:String = numericValue.toFixed(precision);
Result:
fix = "1."
Why is this?
(BTW - on other numbers in the representataion of X.XXXXXXe-YY with percision bigger than 0 we get the correct result of 0)
This is a bug in Flash Player (FP-5141). It has been around for quite a while. The bug report says it is fixed, but it is not as of Flash Player 11.5.