# Why map function in named tuple is outputing only one item

**URL:** <https://discourse.julialang.org/t/why-map-function-in-named-tuple-is-outputing-only-one-item/99410>\
**Category:** General Usage\
**Tags:** question, namedtuple\
**Created:** [May 25, 2023, 9:23pm UTC](https://discourse.julialang.org/t/why-map-function-in-named-tuple-is-outputing-only-one-item/99410 "2023-05-25T21:23:01Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![jcbritobr](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jcbritobr/32/219275_2.png) [@jcbritobr](https://discourse.julialang.org/u/jcbritobr)\
**Post date:** [May 25, 2023, 9:23pm UTC](https://discourse.julialang.org/t/why-map-function-in-named-tuple-is-outputing-only-one-item/99410/1 "2023-05-25T21:23:02Z")

</div>

Hello, good afternoon

Why this named tuple is being outputed with a single mean when using map function?

```julia
	aq = readdlm("data.dat")
	data = (set1=(x=aq[:,1], y=aq[:, 2]),
			set2=(x=aq[:,3], y=aq[:, 4]),
			set3=(x=aq[:,5], y=aq[:, 6]),
			set4=(x=aq[:,7], y=aq[:, 8])
	)

      mean(s -> mean(s.x), data)

```

In my understand the output needs to be a vector of means

---

<div class="post-metadata">

**Author:** ![LeePhillips](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/leephillips/32/205514_2.png) [@LeePhillips](https://discourse.julialang.org/u/LeePhillips)\
**Post date:** [May 25, 2023, 9:33pm UTC](https://discourse.julialang.org/t/why-map-function-in-named-tuple-is-outputing-only-one-item/99410/2 "2023-05-25T21:33:14Z")

</div>

`mean()` returns a number. Maybe you want `mean.()`?

---

<div class="post-metadata">

**Author:** ![jcbritobr](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jcbritobr/32/219275_2.png) [@jcbritobr](https://discourse.julialang.org/u/jcbritobr)\
**Post date:** [May 25, 2023, 9:39pm UTC](https://discourse.julialang.org/t/why-map-function-in-named-tuple-is-outputing-only-one-item/99410/4 "2023-05-25T21:39:45Z")

</div>

no, my bad. I used mean when I needed used map

---

<div class="post-metadata">

**Author:** ![jcbritobr](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jcbritobr/32/219275_2.png) [@jcbritobr](https://discourse.julialang.org/u/jcbritobr)\
**Post date:** [May 25, 2023, 9:40pm UTC](https://discourse.julialang.org/t/why-map-function-in-named-tuple-is-outputing-only-one-item/99410/5 "2023-05-25T21:40:37Z")

</div>

But thank you to show me the issue.