# Setindex for TSFrame from TSFrames.jl

**URL:** <https://discourse.julialang.org/t/setindex-for-tsframe-from-tsframes-jl/117948>\
**Category:** General Usage\
**Tags:** question\
**Created:** [August 8, 2024, 9:29am UTC](https://discourse.julialang.org/t/setindex-for-tsframe-from-tsframes-jl/117948 "2024-08-08T09:29:43Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![EOhneberg](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/eohneberg/32/45704_2.png) [@EOhneberg](https://discourse.julialang.org/u/EOhneberg)\
**Post date:** [August 8, 2024, 9:29am UTC](https://discourse.julialang.org/t/setindex-for-tsframe-from-tsframes-jl/117948/1 "2024-08-08T09:29:44Z")

</div>

Hi everyone,

This is my first question so please let me know if I am doing something wrong.

I used the TSFrames.jl package and ran into the following issue.

I have a TSFrame of stock prices:

```julia
tsf = DataFrame(timestamp = Date(2010,1,1):Day(1):Date(2010,1,4), p1 = rand(4),p2 = rand(4)) |> TSFrame

```

And I now want to build a wealth index (calculate long returns and accumulate them).

Calculating the log returns is easy:

```julia
tsf = diff(log.(tsf))

4×2 TSFrame with Date Index
 Index p1_log p2_log
 Date Float64? Float64?
─────────────────────────────────────────────
 2010-01-01 missing missing
 2010-01-02 0.522848 0.0317818
 2010-01-03 -0.172255 0.275094
 2010-01-04 -1.04826 -0.266552

```

Now the first value is missing because no difference can be calculated. But because I want to accumulate to build a wealth index that starts at 0 for log returns or 1 for normal returns I would like to set these missing values to 0. Ideally, I would like to do this in a loop where I reference either the column index or the column names (want to do this for many etc.)

What works is this:

```julia
tsf.p1_log[1] = 0.0

```

What does not work is:

```julia
tsf[1,:] .= 0.0
tsf[1,:p1_log] = 0.0
tsf[:,:p1_log][1] = 0.0

```

I have also tried setindex! which doesn’t work either.

I am doing it in a very hacky way through eval. I think that there must be a simpler way.  
What I do now is:

```julia
for n in names(tsf)
    eval(Meta.parse("tsf.$(n)[1] = 0.0"))
end

```

Even worse I need to do this again because there is no implementation for `cumsum` it seems.  
I think this is a bit of an oversight given that it is very common to accumulate log returns to get cumulative returns.  
What I do:

```julia
for n in names(tsf)
    eval(Meta.parse("tsf.$n[1:end] = cumsum(tsf[:,:$n])"))
end

```

So I guess my question is does anyone know how to write new values to cells or entire columns in a TSFrame where one can either supply a column index or a column name through a loop?

Thanks

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<div class="post-metadata">

**Author:** ![nilshg](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/nilshg/32/2283_2.png) [@nilshg](https://discourse.julialang.org/u/nilshg)\
**Post date:** [August 8, 2024, 10:09am UTC](https://discourse.julialang.org/t/setindex-for-tsframe-from-tsframes-jl/117948/2 "2024-08-08T10:09:31Z")

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That is a bit odd, maybe just use DataFrames instead?

Anyway if you’re resorting to `eval(Meta.parse` in some data wrangling code there’s about a 99.7% chance (disclaimer: made up number!) that you’re doing it wrong ™

The dot access is just syntactic sugar for a `getproperty` call, so you should be able to do

```julia
for n in names(tsf)
    getproperty(tsf, n)[begin] = 0.0
end

```

(the `begin` is more general than `[1]`, I suppose this isn’t an issue for a `TSFrame` which probably won’t have some sort of offset array as a column)

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<div class="post-metadata">

**Author:** ![EOhneberg](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/eohneberg/32/45704_2.png) [@EOhneberg](https://discourse.julialang.org/u/EOhneberg)\
**Post date:** [August 8, 2024, 10:16am UTC](https://discourse.julialang.org/t/setindex-for-tsframe-from-tsframes-jl/117948/3 "2024-08-08T10:16:46Z")

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I am specifically trying to show the integration of my package with TSFrames.jl so resorting to DataFrames.jl is not ideal.

I guess I was just assuming to be able to do the same kind of indexing as with DataFrames as it is built on it.

Thanks for your code! With a slight adjustment it works like a charm:

```julia
for n in names(tsf)
    getproperty(tsf, Symbol(n))[begin] = 0.0
end

```

Edit: Should I make yours the solution? or the one that works with the Symbol call?

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<div class="post-metadata">

**Author:** ![nilshg](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/nilshg/32/2283_2.png) [@nilshg](https://discourse.julialang.org/u/nilshg)\
**Post date:** [August 8, 2024, 10:27am UTC](https://discourse.julialang.org/t/setindex-for-tsframe-from-tsframes-jl/117948/4 "2024-08-08T10:27:55Z")

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Mark whichever one you want, there’s no magical internet points for solutions on Discourse 😃

And apologies, sometimes I still forget that `names` returns strings and `getproperty` operates on symbols only, it’s the memory of the good old days I guess when DataFrames would only accept symbols for column names…

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<div class="post-metadata">

**Author:** ![chiraganand](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/chiraganand/32/32787_2.png) [@chiraganand](https://discourse.julialang.org/u/chiraganand)\
**Post date:** [August 13, 2024, 4:19am UTC](https://discourse.julialang.org/t/setindex-for-tsframe-from-tsframes-jl/117948/5 "2024-08-13T04:19:54Z")

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> [@EOhneberg](#):
>
> What does not work is:
> 
> ```julia
> tsf[1,:] .= 0.0
> tsf[1,:p1_log] = 0.0
> tsf[:,:p1_log][1] = 0.0
> 
> ```

TSFrames, currently, does not support `setindex()` functions. I have created an issue for this [here](https://github.com/xKDR/TSFrames.jl/issues/204).

Also, created an [issue](https://github.com/xKDR/TSFrames.jl/issues/205) to implement `cumsum`.