# First row of matrix as 1\*n vector

**URL:** <https://discourse.julialang.org/t/first-row-of-matrix-as-1-n-vector/9626>\
**Category:** New to Julia\
**Tags:** question\
**Created:** [March 10, 2018, 12:54am UTC](https://discourse.julialang.org/t/first-row-of-matrix-as-1-n-vector/9626 "2018-03-10T00:54:31Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![Yifan\_Liu](https://avatars.discourse-cdn.com/v4/letter/y/4da419/32.png) [@Yifan\_Liu](https://discourse.julialang.org/u/Yifan_Liu)\
**Post date:** [March 10, 2018, 12:54am UTC](https://discourse.julialang.org/t/first-row-of-matrix-as-1-n-vector/9626/1 "2018-03-10T00:54:31Z")

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When I subset the first row of a matrix, I would like to make it a 1_n vector instead of a n_1 vector

```julia
f = [1 2 3; # 3×3 Array
    3 4 5;
    6 7 8]

f[1, :] # first row 3×1 array
f[1:2, :] # first 2 rows 2×3 array
f[:, 1] # first column 3×1 array

```

Intuitively, the first row of a matrix times the first column of the matrix should make sense, like this

```julia

f[1, :] * f[:, 1]

```

But I have to do this:

```julia

f[1, :] ' * f[:, 1]

```

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<div class="post-metadata">

**Author:** ![yuyichao](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/yuyichao/32/20_2.png) [@yuyichao](https://discourse.julialang.org/u/yuyichao)\
**Post date:** [March 10, 2018, 1:01am UTC](https://discourse.julialang.org/t/first-row-of-matrix-as-1-n-vector/9626/2 "2018-03-10T01:01:35Z")

</div>

> [@Yifan\_Liu](#):
>
> f[1, :]

`f[1:1, :]`

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<div class="post-metadata">

**Author:** ![Yifan\_Liu](https://avatars.discourse-cdn.com/v4/letter/y/4da419/32.png) [@Yifan\_Liu](https://discourse.julialang.org/u/Yifan_Liu)\
**Post date:** [March 10, 2018, 1:13am UTC](https://discourse.julialang.org/t/first-row-of-matrix-as-1-n-vector/9626/3 "2018-03-10T01:13:25Z")

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Thanks, but why f[1, :] does not work as f[1:1, :].

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<div class="post-metadata">

**Author:** ![stevengj](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/stevengj/32/71_2.png) [@stevengj](https://discourse.julialang.org/u/stevengj)\
**Post date:** [March 10, 2018, 1:20am UTC](https://discourse.julialang.org/t/first-row-of-matrix-as-1-n-vector/9626/4 "2018-03-10T01:20:48Z")

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See the discussion at [https://github.com/JuliaLang/julia/issues/231](https://github.com/JuliaLang/julia/issues/231)

You can also do `array[1,:]'`

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<div class="post-metadata">

**Author:** ![Yifan\_Liu](https://avatars.discourse-cdn.com/v4/letter/y/4da419/32.png) [@Yifan\_Liu](https://discourse.julialang.org/u/Yifan_Liu)\
**Post date:** [March 10, 2018, 1:33am UTC](https://discourse.julialang.org/t/first-row-of-matrix-as-1-n-vector/9626/5 "2018-03-10T01:33:19Z")

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why f[:, 1] does not have to be f[:, 1:1]

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<div class="post-metadata">

**Author:** ![yuyichao](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/yuyichao/32/20_2.png) [@yuyichao](https://discourse.julialang.org/u/yuyichao)\
**Post date:** [March 10, 2018, 1:48am UTC](https://discourse.julialang.org/t/first-row-of-matrix-as-1-n-vector/9626/6 "2018-03-10T01:48:07Z")

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What do you mean? FWIW,

> [@Yifan\_Liu](#):
>
> f[1, :] # first row 3×1 array  
> f[1:2, :] # first 2 rows 2×3 array  
> f[:, 1] # first column 3×1 array

is wrong.

The correct version is

```julia
f[1, :] # first row 3 array
f[1:2, :] # first 2 rows 2×3 array
f[:, 1] # first column 3 array

```

There is no x1 there.