[R] Fill in empty cell in data.frame from previous value

[Bert Gunter]

You need to go through some tutorials, not expect us to tutor you
here. That is not the purpose of this list (although we do some of
this indirectly of course). There are many good online tutorials --
search or see here:  https://www.rstudio.com/online-learning/#R  . Or
start by going through the Intro to R tutorial that ships with R.

Cheers,
Bert
Bert Gunter

"The trouble with having an open mind is that people keep coming along
and sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )


On Sun, Jun 25, 2017 at 12:11 AM, Jim Lemon <drjimlemon at gmail.com> wrote:
> Hi Chris,
> You may know about the *apply family of functions. These slice various
> data structures and "apply" a specified function to each slice,
> usually returning a list of return values. As far as I am aware, you
> can't access adjacent rows unless you reformat the data structure.
>
> There is a way to do this particular job. It requires the sequence
> operator (:), the ifelse function and indexing. What you do is to
> create a sequence of all the values in the element "names", then
> subtract 1 for all the NA (or any other specified value) values and
> use the resulting vector to index the original element "names". It
> won't work if the first value is NA, nor will it work for more than
> one NA in a row. I realize that this is pretty obscure, but you said
> that you didn't just want the solution. It's a one-liner.
>
> Jim
>
> On Sun, Jun 25, 2017 at 3:49 AM, Christophe Elek
> <christophe.elek at gmail.com> wrote:
>> Hello Total newbie here... I hope I read the guide properly
>>
>> I have the following data.frame (I read it from a CSV file I cannot change)
>>
>>   names val
>> 1 Mandy   1
>> 2         2
>> 3 John    2
>> 4         2
>>
>> I want to read the row number 2, but I want the first column to be “Mandy” and not null
>>
>> print (frame[2,])
>> 2 Mandy   2
>>
>> I can manipulate the data.frame once loaded
>> How can I fill all cell in column “names” with the previous value ?
>> Or is there a function that will get me the row and fill the “names” column ?
>>
>> NOTA BENE: I do not want the answer, I want to find it myself but I need guidance
>> If there is a function, tell me the library and I will search
>> If this is an algorithm, tell me generally how you would do and let me scratch my head first 😊
>>
>> Thanks Chris
>>
>>
>>         [[alternative HTML version deleted]]
>>
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>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.