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Data Science Wolfram Language

Convert Dataset into array

Rashmi Dhakad

Posted 2 years ago

Hello, I am trying to perform the following code on a dataset: Dataset[1]=-1; For [i=2,i<7000,i++, Dataset[i]=Dataset[i-1]+Dataset[i+1] ] The only way i can see to make this happen is to convert the dataset into an array and performing the loop. Here is a sample of the Dataset: {-1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, -1, \ 0, 0, 1, -1, 1, 0, -1, 1, 1, -1, 1, 0, 0, 0, 0, 0, -1, 0, 0, -1, 1, 1, 1,....} Here is the result i wanna achieve: {-1, -1, 0, 0, 0, 1, 1, 2, 2, 2, 3, 3, 3, 4, 5, 6, 6, 7, 8, 9, 8, 8, \ 8, 9, 8, 9, 9, 8, 9, 10, 9, 10, 10, 10, 10, 10, 10, 9, 9, 9, 8, 9, 10,....} I wanna store the result in the dataset as i am performing further operations on it afterwards. Any help would be appreciated. Thanks.

POSTED BY: Rashmi Dhakad

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Eric Rimbey

Posted 2 years ago

Nice Rohit. I was distracted by the whole Dataset thing.

POSTED BY: Eric Rimbey

Rohit Namjoshi

Posted 2 years ago

Hi Rashmi, Here is one way to do this in-place modification data = {-1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, -1, 0, 0, 1, -1, 1, 0, -1, 1, 1, -1, 1, 0, 0, 0, 0, 0, -1, 0, 0, -1, 1, 1, 1}; Make a copy so the original data is preserved. dataSum = data; Do[dataSum[[i]] = dataSum[[i - 1]] + dataSum[[i + 1]], {i, 2, Length@data - 1}] dataSum (* {-1, -1, 0, 0, 0, 1, 1, 2, 2, 2, 3, 3, 3, 4, 5, 6, 6, 7, 8, 9, 8, 8, 8, 9, 8, 9, 9, 8, 9, 10, 9, 10, 10, 10, 10, 10, 10, 9, 9, 9, 8, 9, 10, 11, 1} *}

Hi Rashmi,

Here is one way to do this in-place modification

data = {-1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 
   1, -1, 0, 0, 1, -1, 1, 0, -1, 1, 1, -1, 1, 0, 0, 0, 0, 0, -1, 0, 
   0, -1, 1, 1, 1};

Make a copy so the original data is preserved.

dataSum = data;
Do[dataSum[[i]] = dataSum[[i - 1]] + dataSum[[i + 1]], {i, 2, Length@data - 1}]

dataSum
(* {-1, -1, 0, 0, 0, 1, 1, 2, 2, 2, 3, 3, 3, 4, 5, 6, 6, 7, 8, 9, 8, 8,
8, 9, 8, 9, 9, 8, 9, 10, 9, 10, 10, 10, 10, 10, 10, 9, 9, 9, 8, 9,
10, 11, 1} *}

POSTED BY: Rohit Namjoshi

Eric Rimbey

Posted 2 years ago

Dataset is typically used for data that has more structure than a List. In your case, I see no extra structure, so why are you using Dataset? If there is no compelling reason, I'd suggest you just stick with List. Your relation, Dataset[i]=Dataset[i-1]+Dataset[i+1], is referencing "forward" (i + 1), and so it's not going to resolve to anything. Why did you only initialize the first element of your list? Also, since Dataset is a built-in symbol, you're not going to be able to redefine it like this. Looking at your two Lists, I can't figure out what relation you actually intended. But maybe you're trying to do something like this: start = {-1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, -1, 0, 0, 1, -1, 1, 0, -1, 1, 1, -1, 1, 0, 0, 0, 0, 0, -1, 0, 0, -1, 1}; finish = {-1}; For[i = 2, i < 10, i++, AppendTo[finish, start[[i - 1]] + start[[i + 1]]]] This doesn't give your desired result, but maybe you can tweak it. Anyway, some more clarity about what you're trying to do would help. It was a good idea to provide your input and expected output, but unfortunately I just can't understand it.

POSTED BY: Eric Rimbey

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