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Jaakko Seppälä

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since Nov 08, 2020
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Recent posts by Jaakko Seppälä

I think the following will do the job:

2 weeks ago
I mean that it would be nice to see what kind of regression models the data a good way, and what are the coefficients of such a model. If this is too hard, it is sufficient to find real numbers a and b such that e^(a+bx) fits to the data the best way is sense of ordinary least squares approximation. I try to learn how to implement regression and matrix algebra to JavaScript.
2 weeks ago
In JavaScript, how can I do regression estimates from data? I mean, I have data of the form
1960: 200000
1970: 400000
1980: 600000
1990: 1000000
2000: 1800000
2010: 3300000
My goal is to predict what is the value of 2020 if the growth remains the same. The problem was given as how a population of particular artificial country will grow so I am not sure if the exponential model describes the growth well enough.
2 weeks ago
Could anyone help me with the following exercise:

From https://tiko.jamk.fi/~tuito/tira/dst2mapit.txt you can see three Map data structures of shops: the name of the shop and prices of the shop. Make three functions that returns the following map: Map { 'ykauppa' => 26 }. The key is the name of the shop that sum of the items is the smallest, so we are looking the cheapest shop.

I have been given the following hints: 1) sum(shop) returns the sum of prices of the items in a shop (map.values()). 2) createSumMap(key, ...shops) creates and returns a new map that key-value pairs contains shops and the sum of items.

3) minValueMap(mapX) -function creates the map from previous map. One can use for example forEach.

I was given the following test file:


My effort was

But this returns an error:

What is my mistake? Do I have to implement also the function get? I thought that it is enough is the function returns a suitable map.
In JavaScript, how can I compute the sum of the numerical values of a map? Why do the following returns 0 instead of 35? In the exercise, the Map structure shop1 was given so the solution is supposed to do without modifying the lines where shop1 is constructed.