Fill in empty cell in data.frame from previous value

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Fill in empty cell in data.frame from previous value

celek
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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Re: Fill in empty cell in data.frame from previous value

Jim Lemon-4
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
<[hidden email]> 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]]
>
> ______________________________________________
> [hidden email] 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.

______________________________________________
[hidden email] 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.
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Re: Fill in empty cell in data.frame from previous value

Bert Gunter-2
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 <[hidden email]> 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
> <[hidden email]> 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]]
>>
>> ______________________________________________
>> [hidden email] 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.
>
> ______________________________________________
> [hidden email] 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.

______________________________________________
[hidden email] 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.
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Re: Fill in empty cell in data.frame from previous value

Boris Steipe
In reply to this post by celek
Run it through a loop. I assume the cell contents is NA (Not Available). Test for it with is.na(). Whenever that returns TRUE, replace the NA value with the value from the previous row.

Cheers,
B.



> On Jun 24, 2017, at 1:49 PM, Christophe Elek <[hidden email]> 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]]
>
> ______________________________________________
> [hidden email] 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.

______________________________________________
[hidden email] 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.
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Re: Fill in empty cell in data.frame from previous value

celek
In reply to this post by Jim Lemon-4
Perfect Jim, that Is exactly what I needed – let me check that ...
Cheers

From: Jim Lemon
Sent: June 25, 2017 3:11 AM
To: Christophe Elek
Cc: [hidden email]
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
<[hidden email]> 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]]
>
> ______________________________________________
> [hidden email] 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.


        [[alternative HTML version deleted]]

______________________________________________
[hidden email] 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.
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Re: Fill in empty cell in data.frame from previous value

celek
In reply to this post by Boris Steipe
Excellent Boris, thx – this helps

From: Boris Steipe
Sent: June 25, 2017 11:23 AM
To: Christophe Elek
Cc: [hidden email]
Subject: Re: [R] Fill in empty cell in data.frame from previous value

Run it through a loop. I assume the cell contents is NA (Not Available). Test for it with is.na(). Whenever that returns TRUE, replace the NA value with the value from the previous row.

Cheers,
B.



> On Jun 24, 2017, at 1:49 PM, Christophe Elek <[hidden email]> 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]]
>
> ______________________________________________
> [hidden email] 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.



        [[alternative HTML version deleted]]

______________________________________________
[hidden email] 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.
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Re: Fill in empty cell in data.frame from previous value

Göran Broström-3
In reply to this post by celek
 > library(tidyr)
 > ?fill

Göran

On 2017-06-24 19:49, Christophe Elek 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]]
>
> ______________________________________________
> [hidden email] 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.
>

______________________________________________
[hidden email] 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.
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Re: Fill in empty cell in data.frame from previous value

Jim Lemon-4
In reply to this post by celek
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 <[hidden email]>
wrote:

> Perfect Jim, that Is exactly what I needed – let me check that ...
>
> Cheers
>
>
>
> *From: *Jim Lemon <[hidden email]>
> *Sent: *June 25, 2017 3:11 AM
> *To: *Christophe Elek <[hidden email]>
> *Cc: *[hidden email]
> *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
>
> <[hidden email]> 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]]
>
> >
>
> > ______________________________________________
>
> > [hidden email] 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.
>
>
>

        [[alternative HTML version deleted]]

______________________________________________
[hidden email] 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.
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Re: Fill in empty cell in data.frame from previous value

PIKAL Petr
In reply to this post by celek
Hi

Maybe I am missing something but in package "zoo" is function "na.locf", which fills empty cells with previous value.

So when you read your file

dat<-read.table("....", na="")

you can use

library(zoo)
sapply(dat, na.locf)

the only problem is that it changes factors to numeric representation. It is solved here

https://stackoverflow.com/questions/22771260/na-locf-converts-data-from-numeric-to-character

Cheers
Petr

> -----Original Message-----
> From: R-help [mailto:[hidden email]] On Behalf Of Christophe
> Elek
> Sent: Sunday, June 25, 2017 5:26 PM
> To: Boris Steipe <[hidden email]>
> Cc: [hidden email]
> Subject: Re: [R] Fill in empty cell in data.frame from previous value
>
> Excellent Boris, thx – this helps
>
> From: Boris Steipe
> Sent: June 25, 2017 11:23 AM
> To: Christophe Elek
> Cc: [hidden email]
> Subject: Re: [R] Fill in empty cell in data.frame from previous value
>
> Run it through a loop. I assume the cell contents is NA (Not Available). Test for
> it with is.na(). Whenever that returns TRUE, replace the NA value with the
> value from the previous row.
>
> Cheers,
> B.
>
>
>
> > On Jun 24, 2017, at 1:49 PM, Christophe Elek <[hidden email]>
> 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]]
> >
> > ______________________________________________
> > [hidden email] 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.
>
>
>
>       [[alternative HTML version deleted]]
>
> ______________________________________________
> [hidden email] 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.

________________________________
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[hidden email] mailing list -- To UNSUBSCRIBE and more, see
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.