### Author:  [@yakir12](https://discourse.julialang.org/u/yakir12)
#### Post date: [August 6, 2018, 7:33am UTC](https://discourse.julialang.org/t/sequentially-add-data-to-a-dataframe/12927/1 "2018-08-06T07:33:55Z")
I often need to populate a `DataFrame` sequentially, one iteration at a time. I therefore end up initiating a `DataFrame` with mock data but with the correct types, deleting that first row, and then iterating through the real data I want to populate it with.
It looks like this:
```julia
df = DataFrame(place = "", quantity = 0, when = Date(0))
deleterows!(df, 1)
for i in 1:n
#
push!(df, (p, q, w))
end
```
This works, but I wonder if there is a better way to do this…
Thanks!
---
### Author:  [@bkamins](https://discourse.julialang.org/u/bkamins)
#### Post date: [August 6, 2018, 8:38am UTC](https://discourse.julialang.org/t/sequentially-add-data-to-a-dataframe/12927/2 "2018-08-06T08:38:35Z")
I use exactly the same pattern except that I create a `DataFrame` like this:
```julia
df = DataFrame(place=String[], quantity=Int[], when=Date[])
```
to avoid deleting the first row later.
Alternatively there are constructors that take type of the data and number of rows and create `DataFrame` of an appropriate size and then you do not `push!` a row but assign it. But typically I prefer `push!` as it is simpler to think of.
---
### Author:  [@yakir12](https://discourse.julialang.org/u/yakir12)
#### Post date: [August 6, 2018, 8:43am UTC](https://discourse.julialang.org/t/sequentially-add-data-to-a-dataframe/12927/3 "2018-08-06T08:43:09Z")
Of course! Thanks.
> [@bkamins](#):
>
> Alternatively there are constructors that take type of the data and number of rows and create `DataFrame` of an appropriate size and then you do not `push!` a row but assign it. But typically I prefer `push!` as it is simpler to think of.
Could you give an example, showcasing the appropriate syntax?
---
### Author:  [@bkamins](https://discourse.julialang.org/u/bkamins)
#### Post date: [August 6, 2018, 8:45am UTC](https://discourse.julialang.org/t/sequentially-add-data-to-a-dataframe/12927/4 "2018-08-06T08:45:57Z")
```julia
julia> DataFrame([Int, Float64, String], [:a, :b, :c], 3)
3×3 DataFrames.DataFrame
│ Row │ a │ b │ c │
├─────┼───────────┼──────────────┼────────┤
│ 1 │ 428567856 │ 2.11741e-315 │ #undef │
│ 2 │ 428567920 │ 5.86393e-316 │ #undef │
│ 3 │ 428567984 │ 5.84443e-316 │ #undef │
julia> DataFrame([Int, Float64, String], [:a, :b, :c], 0)
0×3 DataFrames.DataFrame
```
The second example creates an empty `DataFrame` so you can `push!` into it like above. The first creates an uninitialized `DataFrame` with three rows.
---
### Author:  [@jacobusmmsmit](https://discourse.julialang.org/u/jacobusmmsmit)
#### Post date: [January 9, 2025, 1:47pm UTC](https://discourse.julialang.org/t/sequentially-add-data-to-a-dataframe/12927/5 "2025-01-09T13:47:50Z")
I’m sorry for necroing a thread that is over 6 years old, but I want to add that the comment marked “solution” will throw an error.
For an empty `DataFrame`, bkamins’ first comment works, but for an unitialised `DataFrame` of length `N`, as explained in [another thread](https://discourse.julialang.org/t/how-to-initialize-empty-dataframe-of-specified-size/67421/4), it’s far better to construct and populate the individual columns as length `N` `Vector`s first, then construct the DataFrame from these vectors.