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Fill in empty cell in data.frame from previous value

Jim Lemon

Sun, Jun 25, 2017 2:59 PM

That's the kind of help that we like to provide. And for extra marks, you
can write a small function that will deal with consecutive NA values.

Jim

On Mon, Jun 26, 2017 at 1:25 AM, Christophe Elek <christophe.elek at gmail.com>
wrote:

Perfect Jim, that Is exactly what I needed ? let me check that ...

Cheers



*From: *Jim Lemon <drjimlemon at gmail.com>
*Sent: *June 25, 2017 3:11 AM
*To: *Christophe Elek <christophe.elek at gmail.com>
*Cc: *r-help at r-project.org
*Subject: *Re: [R] Fill in empty cell in data.frame from previous value



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

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Thread (9 messages)

Christophe Elek Fill in empty cell in data.frame from previous value Jun 24 Jim Lemon Fill in empty cell in data.frame from previous value Jun 25 Bert Gunter Fill in empty cell in data.frame from previous value Jun 25 Boris Steipe Fill in empty cell in data.frame from previous value Jun 25 Christophe Elek Fill in empty cell in data.frame from previous value Jun 25 Christophe Elek Fill in empty cell in data.frame from previous value Jun 25 Göran Broström Fill in empty cell in data.frame from previous value Jun 25 Jim Lemon Fill in empty cell in data.frame from previous value Jun 25 PIKAL Petr Fill in empty cell in data.frame from previous value Jun 25