# Anonymous function/comprehension coding
**URL:** https://discourse.julialang.org/t/anonymous-function-comprehension-coding/107775
**Category:** New to Julia
**Tags:** best-practices
**Created:** [December 18, 2023, 3:59pm UTC](https://discourse.julialang.org/t/anonymous-function-comprehension-coding/107775 "2023-12-18T15:59:01Z")
**Posts on this page:** 11
**Page:** 1
### Author:  [@SergeantMike](https://discourse.julialang.org/u/SergeantMike)
#### Post date: [December 18, 2023, 3:59pm UTC](https://discourse.julialang.org/t/anonymous-function-comprehension-coding/107775/1 "2023-12-18T15:59:01Z")
Having a difficult time wrapping my head around Anonymous function and Comprehensions coding, not an easy thing for someone who thinks in ecological terms.
What I am doing is doing a life-table calculation for the proportion of the cohort that has survived at time t. Basically my code looks like this.
```julia
for idx = 1:length (VarData)
buf - = VarData [idx]
push!(cof,(buf/GrandTotal))
end
```
where
buf is the variable represents the number of individuals surviving at each time point and comes from taking the current survivorship and subtracting the number who died.
VarData is a vector array that contains the number of individuals that died in that time period.
GrandTotal is the total number of individuals present at time point zero.
So if initially
buf=60
GrandTotal=60
and VarData=[1 1 6 7 16 19 8 2 0]
this results in the following vector array
[0.983 0.966 0.866 0.75 0.483 0.166 0.033]
which is the survivors (buf) divided by GrandTotal
The code above gives the correct answer but I can’t help but think there is some form of anonymous function or comprehension that I can use to make it more Julia (if that is the right word) that I cannot see.
Mike
---
### Author:  [@IlianPihlajamaa](https://discourse.julialang.org/u/IlianPihlajamaa)
#### Post date: [December 18, 2023, 4:32pm UTC](https://discourse.julialang.org/t/anonymous-function-comprehension-coding/107775/2 "2023-12-18T16:32:06Z")
Maybe something like
```julia
result = (GrandTotal .- cumsum(VarData, dims=2)) ./ GrandTotal
```
?
Haven’t tested it though…
---
### Author:  [@lmiq](https://discourse.julialang.org/u/lmiq)
#### Post date: [December 18, 2023, 4:34pm UTC](https://discourse.julialang.org/t/anonymous-function-comprehension-coding/107775/3 "2023-12-18T16:34:08Z")
In any case, no one-liner will be better than what you wrote, except perhaps for the syntax.
ps: Use commas to separate values in the arrays, to get vector and not 1-line matrices.
---
### Author:  [@vsoler](https://discourse.julialang.org/u/vsoler)
#### Post date: [December 18, 2023, 4:35pm UTC](https://discourse.julialang.org/t/anonymous-function-comprehension-coding/107775/4 "2023-12-18T16:35:51Z")
Try this:
> a = [1, 1, 6, 7, 16, 19, 8, 2, 0]
> (60 .- cumsum(a)) ./ 60
It will give you directly the answer you are looking for.
Please note that there is a period before the minus (-) and before the slash (/). These are necessay in order to add (or divide into) a scalar and a vector.
So you need no loops at all !!!
---
### Author:  [@stevengj](https://discourse.julialang.org/u/stevengj)
#### Post date: [December 18, 2023, 4:38pm UTC](https://discourse.julialang.org/t/anonymous-function-comprehension-coding/107775/5 "2023-12-18T16:38:57Z")
> [@vsoler](#):
>
> These are necessay in order to add (or divide into) a scalar and a vector.
`vector / scalar` is allowed without dot, because `vector * inv(scalar)` is a standard operation on vector spaces, just like `vector + vector`.
However, if you use `vector ./ scalar` and `vector .+ vector`, it computes the same thing but has the advantage of “fusing” with other dot calls. e.g. `(scalar .- vector) ./ scalar)` is computed in a single loop and allocates a single array. See also the [“More Dots” blog post](https://julialang.org/blog/2017/01/moredots/).
(Nor is there is anything wrong with writing a loop “manually” in Julia.)
---
### Author:  [@IlianPihlajamaa](https://discourse.julialang.org/u/IlianPihlajamaa)
#### Post date: [December 18, 2023, 4:40pm UTC](https://discourse.julialang.org/t/anonymous-function-comprehension-coding/107775/6 "2023-12-18T16:40:03Z")
For both @vsoler and my solution, if you keep using a row vector as data (numbers separated by spaces instead of commas) you need to add `dims=2` to the cumsum function as keyword argument.
---
### Author:  [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)
#### Post date: [December 18, 2023, 4:42pm UTC](https://discourse.julialang.org/t/anonymous-function-comprehension-coding/107775/7 "2023-12-18T16:42:43Z")
Also note there are some synthatic errors in the code you posted.
Functions (like `length`) and vectors (like `VarData`) don’t want a space between them and the parameters/index.
---
### Author:  [@SergeantMike](https://discourse.julialang.org/u/SergeantMike)
#### Post date: [December 18, 2023, 10:01pm UTC](https://discourse.julialang.org/t/anonymous-function-comprehension-coding/107775/8 "2023-12-18T22:01:47Z")
I have noted that when Imiq pointed it out.
Note: that the data is imported from a CSV and it is arranged properly in the code. I provided the data within VarData to illustrate in the best way possible what I was trying to accomplish. I apologize for the wrong syntax but it does seem that everyone did understand the goal here.
---
### Author:  [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)
#### Post date: [December 19, 2023, 6:57am UTC](https://discourse.julialang.org/t/anonymous-function-comprehension-coding/107775/9 "2023-12-19T06:57:41Z")
> [@SergeantMike](#):
>
> but it does seem that everyone did understand the goal here.
There are very smart guys in this forum 😉 😉 😉
---
### Author:  [@simsurace](https://discourse.julialang.org/u/simsurace)
#### Post date: [December 19, 2023, 7:33am UTC](https://discourse.julialang.org/t/anonymous-function-comprehension-coding/107775/10 "2023-12-19T07:33:39Z")
I don‘t think that there is anything wrong and un-idiomatic with writing a loop here, maybe it is even easier to understand.
---
### Author:  [@vsoler](https://discourse.julialang.org/u/vsoler)
#### Post date: [December 19, 2023, 11:14am UTC](https://discourse.julialang.org/t/anonymous-function-comprehension-coding/107775/11 "2023-12-19T11:14:56Z")
Thank you, @stevengj, I learnt something new today !!!