# DataFrame: how to change value of a cell without knowing the row number

**URL:** <https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024>\
**Category:** Data\
**Tags:** dataframes\
**Created:** [March 19, 2019, 8:15am UTC](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024 "2019-03-19T08:15:35Z")\
**Posts on this page:** 20\
**Page:** 1

<div class="post-metadata">

**Author:** ![johann.spies](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/johann.spies/32/8805_2.png) [@johann.spies](https://discourse.julialang.org/u/johann.spies)\
**Post date:** [March 19, 2019, 8:15am UTC](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024/1 "2019-03-19T08:15:35Z")

</div>

In the following DataFrame, how do I change the age of Sally without knowing the row number and without changing any other values in the DataFrame?

I have looked at the DataFrames, DataframesMeta and Query documentation and could not figure out a clean way of doing it.

```julia
df = DataFrame(name=["John", "Sally", "Kirk"], age=[23., 42., 59.], children=[3,5,2])
3×3 DataFrame
│ Row │ name │ age │ children │
│ │ String │ Float64 │ Int64 │
├─────┼────────┼─────────┼──────────┤
│ 1 │ John │ 23.0 │ 3 │
│ 2 │ Sally │ 42.0 │ 5 │
│ 3 │ Kirk │ 59.0 │ 2 │

```

---

<div class="post-metadata">

**Author:** ![Ajaychat3](https://avatars.discourse-cdn.com/v4/letter/a/ecd19e/32.png) [@Ajaychat3](https://discourse.julialang.org/u/Ajaychat3)\
**Post date:** [March 19, 2019, 8:18am UTC](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024/2 "2019-03-19T08:18:45Z")

</div>

This should work.

```julia
df[(df[:name] .== "Sally"),:age]=99

```

---

<div class="post-metadata">

**Author:** ![johann.spies](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/johann.spies/32/8805_2.png) [@johann.spies](https://discourse.julialang.org/u/johann.spies)\
**Post date:** [March 19, 2019, 8:34am UTC](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024/3 "2019-03-19T08:34:19Z")

</div>

> [@Ajaychat3](#):
>
> df[(df[:name] .== “Sally”),:age]=99

Thanks @ [Ajaychat3](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024/2)

---

<div class="post-metadata">

**Author:** ![johann.spies](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/johann.spies/32/8805_2.png) [@johann.spies](https://discourse.julialang.org/u/johann.spies)\
**Post date:** [March 19, 2019, 9:00am UTC](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024/4 "2019-03-19T09:00:50Z")

</div>

Wait a bit, here is something strange.

I have a DataFrame dx

```julia
julia> dx = collab_matrix()
249×250 DataFrame. Omitted printing of 235 columns
│ Row │ country │ AD │ AE │ AF │ AG │ AI │ AL │ AM │ AO │ AQ │ AR │ AS │ AT │ AU │ AW │
│ │ String⍰ │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │
├─────┼─────────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┤
│ 1 │ AD │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 2 │ AE │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 3 │ AF │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 4 │ AG │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 5 │ AI │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 6 │ AL │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 7 │ AM │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 8 │ AO │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 9 │ AQ │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 10 │ AR │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 11 │ AS │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 12 │ AT │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 13 │ AU │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
⋮
│ 236 │ VA │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 237 │ VC │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 238 │ VE │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 239 │ VG │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 240 │ VI │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 241 │ VN │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 242 │ VU │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 243 │ WF │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 244 │ WS │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 245 │ YE │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 246 │ YT │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 247 │ ZA │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 248 │ ZM │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 249 │ ZW │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │

```

```julia
julia> d = first(dx, 5)
5×250 DataFrame. Omitted printing of 235 columns
│ Row │ country │ AD │ AE │ AF │ AG │ AI │ AL │ AM │ AO │ AQ │ AR │ AS │ AT │ AU │ AW │
│ │ String⍰ │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │
├─────┼─────────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┤
│ 1 │ AD │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 2 │ AE │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 3 │ AF │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 4 │ AG │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 5 │ AI │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │

julia> d
5×250 DataFrame. Omitted printing of 235 columns
│ Row │ country │ AD │ AE │ AF │ AG │ AI │ AL │ AM │ AO │ AQ │ AR │ AS │ AT │ AU │ AW │
│ │ String⍰ │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │
├─────┼─────────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┤
│ 1 │ AD │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 2 │ AE │ 0 │ 0 │ 0 │ 6 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 3 │ AF │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 4 │ AG │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 5 │ AI │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │

```

This works as expected, but

```julia
julia> dx[(dx[:country] .== "AE"),:AG]=6
6
julia> first(dx, 6)
6×250 DataFrame. Omitted printing of 235 columns
│ Row │ country │ AD │ AE │ AF │ AG │ AI │ AL │ AM │ AO │ AQ │ AR │ AS │ AT │ AU │ AW │
│ │ String⍰ │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │ Int64 │
├─────┼─────────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┤
│ 1 │ AD │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 2 │ AE │ 6 │ 6 │ 6 │ 6 │ 6 │ 6 │ 6 │ 6 │ 6 │ 6 │ 6 │ 6 │ 6 │ 6 │
│ 3 │ AF │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 4 │ AG │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 5 │ AI │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │
│ 6 │ AL │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │

```

It changes the whole row as soon as I work with the bigger DataFrame!

A bug?

---

<div class="post-metadata">

**Author:** ![Ajaychat3](https://avatars.discourse-cdn.com/v4/letter/a/ecd19e/32.png) [@Ajaychat3](https://discourse.julialang.org/u/Ajaychat3)\
**Post date:** [March 19, 2019, 10:31am UTC](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024/5 "2019-03-19T10:31:58Z")

</div>

I have worked on quite big dataframes and haven’t noticed such an issue. Check if are using the latest version of packages.

---

<div class="post-metadata">

**Author:** ![bkamins](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/bkamins/32/208538_2.png) [@bkamins](https://discourse.julialang.org/u/bkamins)\
**Post date:** [March 19, 2019, 10:35am UTC](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024/6 "2019-03-19T10:35:34Z")

</div>

> [@johann.spies](#):
>
> A bug?

This should not happen. Can you please submit a reproducible example as an Issue in DataFrames.jl?

As a side note - in the future we will probably make DataFrames.jl consistent with Base and assigning a scalar to a collection of row entries will require broadcasting using `.=`, but this is still being discussed.

---

<div class="post-metadata">

**Author:** ![kdyrhage](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kdyrhage/32/2326_2.png) [@kdyrhage](https://discourse.julialang.org/u/kdyrhage)\
**Post date:** [March 19, 2019, 11:55am UTC](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024/7 "2019-03-19T11:55:20Z")

</div>

How is `collab_matrix()` defined? I think the columns are all pointing to the same array, which happens if you do something like this:

```julia
julia> using DataFrames
julia> a = [0, 0, 0];
julia> dx = DataFrame(AD = a, AE = a);
julia> dx[1, 1] = 1;
julia> dx
3×2 DataFrame
│ Row │ AD │ AE │
│ │ Int64 │ Int64 │
├─────┼───────┼───────┤
│ 1 │ 1 │ 1 │
│ 2 │ 0 │ 0 │
│ 3 │ 0 │ 0 │

```

---

<div class="post-metadata">

**Author:** ![johann.spies](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/johann.spies/32/8805_2.png) [@johann.spies](https://discourse.julialang.org/u/johann.spies)\
**Post date:** [March 19, 2019, 2:26pm UTC](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024/8 "2019-03-19T14:26:51Z")

</div>

Thank you [kdyrhage](https://discourse.julialang.org/u/kdyrhage), you are on the money!

In my `collab_matrix()` I used exactly that method to populate each column with a series of zeros.

I had

```julia
l = repeat(0:0, inner = r)
for i in 1:r
        _,z = size(dx)
        e = c[:code][i]
        insertcols!(dx, z+1, Symbol(e) => l))

```

in my function. Changing `insertcols!` to

```julia
 insertcols!(dx, z+1, Symbol(e) => repeat(0:0, inner = r))

```

did the trick.

Valuable lesson learnt.

---

<div class="post-metadata">

**Author:** ![ampbj](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ampbj/32/19518_2.png) [@ampbj](https://discourse.julialang.org/u/ampbj)\
**Post date:** [February 1, 2021, 11:43am UTC](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024/9 "2021-02-01T11:43:52Z")

</div>

@bkamins I am wondering if there is a faster way to replace value of a cell in place?  
I am working on an algorithm that does a lot of dataframes manipulation in place and does not seem to be running fast? or perhaps dataframes is not designed for these operations?

one operation seems like to be taking around 3 ms.

```julia
@btime data[data.Timestamp .== "20201231 165800", :Close] = [100]
  2.665 ms (8 allocations: 50.03 KiB)

```

Thank you

---

<div class="post-metadata">

**Author:** ![bkamins](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/bkamins/32/208538_2.png) [@bkamins](https://discourse.julialang.org/u/bkamins)\
**Post date:** [February 1, 2021, 1:11pm UTC](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024/10 "2021-02-01T13:11:08Z")

</div>

This is not related to DataFrames.jl. Use [GitHub - andyferris/AcceleratedArrays.jl: Arrays with acceleration indices](https://github.com/andyferris/AcceleratedArrays.jl) for `:Timestamp` column for such use cases if you need to be fast.

---

<div class="post-metadata">

**Author:** ![jakewilliami](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jakewilliami/32/18945_2.png) [@jakewilliami](https://discourse.julialang.org/u/jakewilliami)\
**Post date:** [May 12, 2021, 9:08pm UTC](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024/11 "2021-05-12T21:08:00Z")

</div>

Expanding on @Ajaychat3’s answer for those wondering how to do this with multiple conditions, you can do this:

```julia
df[((df.name .== "Sally") .& (df.ancient .== true)), :age] .= 99

```

You have to use `&` because you are creating a `BitArray`, and you need to broadcast it because there are two of them. You may also need to broadcast the assignment (`.=`) to change multiple values.

---

<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:** [May 12, 2021, 9:14pm UTC](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024/12 "2021-05-12T21:14:45Z")

</div>

> [@jakewilliami](#):
>
> ```julia
> df[((df.name .== "Sally") .& (df.ancient .== true)), :age] .= 99
> 
> ```

You’ve got one redundant set of brackets there,

```julia
df[(df.name .== "Sally") .& (df.ancient .== true), :age] .= 99

```

will do.

---

<div class="post-metadata">

**Author:** ![sai\_matcha](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/sai_matcha/32/35801_2.png) [@sai\_matcha](https://discourse.julialang.org/u/sai_matcha)\
**Post date:** [February 14, 2022, 4:23pm UTC](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024/13 "2022-02-14T16:23:17Z")

</div>

it is allowing me change age to a number. im intersted to know how can i change “sally” age to missing ?  
Thank you

---

<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:** [February 14, 2022, 4:25pm UTC](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024/14 "2022-02-14T16:25:41Z")

</div>

```julia
df[(df.name .== "Sally") .& (df.ancient .== true), :age] .= missing

```

(actually given I complained about extra brackets above, now with broadcasted `&&` we can do

```julia
df[df.name .== "Sally" .&& df.ancient .== true, :age] .= missing

```

but for this the `age` column has to be a `Union{Missing, Int64}`, so one might have to do `allowmissing!(df, :age)` first.

---

<div class="post-metadata">

**Author:** ![sai\_matcha](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/sai_matcha/32/35801_2.png) [@sai\_matcha](https://discourse.julialang.org/u/sai_matcha)\
**Post date:** [February 14, 2022, 4:29pm UTC](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024/15 "2022-02-14T16:29:01Z")

</div>

@nilshg thank you

---

<div class="post-metadata">

**Author:** ![bkamins](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/bkamins/32/208538_2.png) [@bkamins](https://discourse.julialang.org/u/bkamins)\
**Post date:** [February 14, 2022, 4:29pm UTC](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024/16 "2022-02-14T16:29:04Z")

</div>

```julia
df.age = @. ifelse(df.name == "Sally" && df.ancient, missing, df.age)

```

or with DataFramesMeta.jl

```julia
@rtransform :age = ifelse(:name == "Sally" && :ancient, missing, :age)

```

---

<div class="post-metadata">

**Author:** ![sai\_matcha](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/sai_matcha/32/35801_2.png) [@sai\_matcha](https://discourse.julialang.org/u/sai_matcha)\
**Post date:** [February 14, 2022, 4:35pm UTC](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024/17 "2022-02-14T16:35:29Z")

</div>

ancient column is not given in the initial query, can i ask how it there in the code ?

---

<div class="post-metadata">

**Author:** ![bkamins](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/bkamins/32/208538_2.png) [@bkamins](https://discourse.julialang.org/u/bkamins)\
**Post date:** [February 14, 2022, 4:37pm UTC](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024/18 "2022-02-14T16:37:10Z")

</div>

I am not sure what you ask about exactly. I have re-written the code that @nilshg proposed in his answer.

---

<div class="post-metadata">

**Author:** ![sai\_matcha](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/sai_matcha/32/35801_2.png) [@sai\_matcha](https://discourse.julialang.org/u/sai_matcha)\
**Post date:** [February 14, 2022, 4:41pm UTC](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024/19 "2022-02-14T16:41:41Z")

</div>

sorry my mistake. i have got the answer from you and @nilshg replies. @johann.spies has only three columns in the dataframe when he created query. suddenly df.ancient started to appear in solutions. i did not understand the source , from whre df.ancient did come from. so i asked is that any reserved term or any other rationale behind that.

Thank you for clearing my doubt. this is just an curious question. but i got solution for my actual problem from your previous post.

---

<div class="post-metadata">

**Author:** ![pdeffebach](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/pdeffebach/32/10320_2.png) [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)\
**Post date:** [February 14, 2022, 5:17pm UTC](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024/20 "2022-02-14T17:17:14Z")

</div>

Maybe a better solution in terms of performance and how to handle missings.

```julia
@rtransform df @passmissing :age = :name == "Sally" ? missing : :age

```

[Next page](https://discourse.julialang.org/t/dataframe-how-to-change-value-of-a-cell-without-knowing-the-row-number/22024.md?page=2)