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Replace NAs in split lists

15 messages · Eric Berger, Ek Esawi, Jeff Newmiller +2 more

#
Hi all--

I stumbled on this problem online. I did not like the solution given
there which was a long UDF. I thought why cannot split and l/s apply
work here. My aim is to split the data frame, use l/sapply, make
changes on the split lists and combine the split lists to new data
frame with the desired changes/output.

The data frame shown below has a column named ID which has 2 variables
a and b; i want to replace the NAs on the Value column by 2, which is
the only numeric entry, for ID=a and by 5 for ID=b.

I worked out the solution but could not replace the results in the split lists.

Original dataframe , df1
  ID ID_2 Firist Value
1  a   aa   TRUE     2
2  a   ab  FALSE    NA
3  a   ac  FALSE    NA
4  b   aa   TRUE     5
5  b   ab  FALSE    NA
Sdf1
$a
ID ID_2 Firist Value
1  a   aa   TRUE     2
2  a   ab  FALSE    NA
3  a   ac  FALSE    NA
$b
  ID ID_2 Firist Value
4  b   aa   TRUE     5
5  b   ab  FALSE    NA
Desired results
ID ID_2 Firist Value
1  a   aa   TRUE    2
2  a   ab  FALSE    2
3  a   ac  FALSE    2

$b
  ID ID_2 Firist Value
4  b   aa   TRUE     5
5  b   ab  FALSE     5

My code

sdf <- split(df1,df$ID)
lapply(sdf, function(z) ifelse(is.na(z$Value),z$Value[!is.na(z$Value)],z$Value))
result:
$ a: num [1:3] 2 2 2
$ b: num [1:2] 5 5

How could I put these two lists back in the split data frame, sdf1?
Then I could use do.call to reassemble a data frame from the split
lists,

Thanks,
EK
#
I just came up with a solution right after i posted the question, but
i figured there must be a better and shorter one.than my solution
sdf1[[1]][1,4]<-lapplyresults[[1]]
sdf1[[2]][1,4]<-lapplyresults[[2]]

EK
On Sun, Jan 7, 2018 at 10:13 PM, Ek Esawi <esawiek at gmail.com> wrote:
#
Hi

library(zoo)

has function na.locf, which probably can do what you want.

so something like (untested)

sdf1.fill<-lapply(sdf1, na.locf)
do.call(rbind, sdf1.fill)

Cheers.
Petr
________________________________
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#
Why do you want to modify df1?

Why not just reassemble the parts as a new data frame and use that going forward in your calculations? That is generally the preferred approach in R so you can re-do your calculations easily if you find a mistake later.
#
Upon closer examination I see that you are not using the split version of 
df1 as I usually would, so here is a reproducible example:

#----
df1 <- read.table( text=
"ID ID_2 Firist Value
1  a   aa   TRUE     2
2  a   ab  FALSE    NA
3  a   ac  FALSE    NA
4  b   aa   TRUE     5
5  b   ab  FALSE    NA
", header=TRUE, as.is=TRUE )

sdf <- split( df1, df1$ID )
# note the extra [ 1 ] in case you have more than one non-NA value 
# per ID
sdf2 <- lapply( sdf
               , function( z ) {
                  z$Value <- ifelse( is.na( z$Value )
                                   , z$Value[ !is.na( z$Value ) ][ 1 ]
                                   , z$Value
                                   )
                  z
                 }
               )
df2 <- do.call( rbind, sdf2 )
df2
#>     ID ID_2 Firist Value
#> a.1  a   aa   TRUE     2
#> a.2  a   ab  FALSE     2
#> a.3  a   ac  FALSE     2
#> b.4  b   aa   TRUE     5
#> b.5  b   ab  FALSE     5

# or using tidyverse methods

library(dplyr)
#>
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#>
#>     filter, lag
#> The following objects are masked from 'package:base':
#>
#>     intersect, setdiff, setequal, union
df3 <- (   df1
        %>% group_by( ID )
        %>% do({
               mutate( .
                     , Value = ifelse( is.na( Value )
                                     , Value[ !is.na( Value ) ][ 1 ]
                                     , Value
                                     )
                     )
            })
        %>% ungroup
        )
df3
#> # A tibble: 5 x 4
#>   ID    ID_2  Firist Value
#>   <chr> <chr> <lgl>  <int>
#> 1 a     aa    T          2
#> 2 a     ab    F          2
#> 3 a     ac    F          2
#> 4 b     aa    T          5
#> 5 b     ab    F          5
#----
On Sun, 7 Jan 2018, Jeff Newmiller wrote:

            
---------------------------------------------------------------------------
Jeff Newmiller                        The     .....       .....  Go Live...
DCN:<jdnewmil at dcn.davis.ca.us>        Basics: ##.#.       ##.#.  Live Go...
                                       Live:   OO#.. Dead: OO#..  Playing
Research Engineer (Solar/Batteries            O.O#.       #.O#.  with
/Software/Embedded Controllers)               .OO#.       .OO#.  rocks...1k
#
Hi

With the example, na.locf seems to be the easiest way.
ID ID_2 Firist Value
1  a   aa   TRUE     2
2  a   ab  FALSE     2
3  a   ac  FALSE     2
4  b   aa   TRUE     5
5  b   ab  FALSE     5

Cheers
Petr
________________________________
Tento e-mail a jak?koliv k n?mu p?ipojen? dokumenty jsou d?v?rn? a jsou ur?eny pouze jeho adres?t?m.
Jestli?e jste obdr?el(a) tento e-mail omylem, informujte laskav? neprodlen? jeho odes?latele. Obsah tohoto emailu i s p??lohami a jeho kopie vyma?te ze sv?ho syst?mu.
Nejste-li zam??len?m adres?tem tohoto emailu, nejste opr?vn?ni tento email jakkoliv u??vat, roz?i?ovat, kop?rovat ?i zve?ej?ovat.
Odes?latel e-mailu neodpov?d? za eventu?ln? ?kodu zp?sobenou modifikacemi ?i zpo?d?n?m p?enosu e-mailu.

V p??pad?, ?e je tento e-mail sou??st? obchodn?ho jedn?n?:
- vyhrazuje si odes?latel pr?vo ukon?it kdykoliv jedn?n? o uzav?en? smlouvy, a to z jak?hokoliv d?vodu i bez uveden? d?vodu.
- a obsahuje-li nab?dku, je adres?t opr?vn?n nab?dku bezodkladn? p?ijmout; Odes?latel tohoto e-mailu (nab?dky) vylu?uje p?ijet? nab?dky ze strany p??jemce s dodatkem ?i odchylkou.
- trv? odes?latel na tom, ?e p??slu?n? smlouva je uzav?ena teprve v?slovn?m dosa?en?m shody na v?ech jej?ch n?le?itostech.
- odes?latel tohoto emailu informuje, ?e nen? opr?vn?n uzav?rat za spole?nost ??dn? smlouvy s v?jimkou p??pad?, kdy k tomu byl p?semn? zmocn?n nebo p?semn? pov??en a takov? pov??en? nebo pln? moc byly adres?tovi tohoto emailu p??padn? osob?, kterou adres?t zastupuje, p?edlo?eny nebo jejich existence je adres?tovi ?i osob? j?m zastoupen? zn?m?.

This e-mail and any documents attached to it may be confidential and are intended only for its intended recipients.
If you received this e-mail by mistake, please immediately inform its sender. Delete the contents of this e-mail with all attachments and its copies from your system.
If you are not the intended recipient of this e-mail, you are not authorized to use, disseminate, copy or disclose this e-mail in any manner.
The sender of this e-mail shall not be liable for any possible damage caused by modifications of the e-mail or by delay with transfer of the email.

In case that this e-mail forms part of business dealings:
- the sender reserves the right to end negotiations about entering into a contract in any time, for any reason, and without stating any reasoning.
- if the e-mail contains an offer, the recipient is entitled to immediately accept such offer; The sender of this e-mail (offer) excludes any acceptance of the offer on the part of the recipient containing any amendment or variation.
- the sender insists on that the respective contract is concluded only upon an express mutual agreement on all its aspects.
- the sender of this e-mail informs that he/she is not authorized to enter into any contracts on behalf of the company except for cases in which he/she is expressly authorized to do so in writing, and such authorization or power of attorney is submitted to the recipient or the person represented by the recipient, or the existence of such authorization is known to the recipient of the person represented by the recipient.
#
Yes, you are right if the IDs are always sequentially-adjacent and the first non-NA value appears in the first record for each ID.
#
You can enforce these assumptions by sorting on multiple columns, which
leads to

na.locf(df1[ order(df1$ID,df1$Value), ])



On Mon, Jan 8, 2018 at 4:19 PM, Jeff Newmiller <jdnewmil at dcn.davis.ca.us>
wrote:

  
  
#
"Enforce" is overstating it... results will differ if there are no non-NA values for a given ID, and there is a potential further discrepancy if there are multiple non-NA values. But these issues were not identified by the OP, so may not be relevant in their case.
#
Thank you Jeff. Your code works, as usual , perfectly. I am just
wondering why if i put the whole code in one line, i get an error
message.
sdf2 <- lapply( sdf, function(z){z$Value
<-ifelse(is.na(z$Value),z$Value[!is.na(z$Value)][1],z$Value)z})
error. unexpected symbol in sdf2

Thanks again

EK
On Mon, Jan 8, 2018 at 3:12 AM, Jeff Newmiller <jdnewmil at dcn.davis.ca.us> wrote:
#
I don't know. You seem to be posting in HTML so your code is mangled. Can you post plain text and use the reprex package to make sure it produces the errorin a clean R session?
#
OPS!  Sorry i did indeed posted the code in HTML; should have known better.

ifelse(is.na(z$Value),z$Value[!is.na(z$Value)][1],z$Value)z})
error. unexpected symbol in sdf2

On Mon, Jan 8, 2018 at 11:44 AM, Jeff Newmiller
<jdnewmil at dcn.davis.ca.us> wrote:
#
I don't get exactly that error message,
  > ifelse(is.na(z$Value),z$Value[!is.na(z$Value)][1],z$Value)z})
  Error: unexpected symbol in "ifelse(is.na(z$Value),z$Value[!is.na
(z$Value)][1],z$Value)z"
The 'symbol' in "unexpected symbol" refers to a "name" ('z' in this case).
The problem is usually at the end of the code snippet shown in the error
message as in
  > f(a)b # missing newline or semicolon?
  Error: unexpected symbol in "f(a)b"
or
  > f(a b) # missing comma?
  Error: unexpected symbol in "f(a b"

You need a newline or semicolon between the end of 'ifelse(...)' and 'z' or
maybe
you don't want the z there at all.

After you fix that it will complain about the unmatched right brace and
parenthesis.



Bill Dunlap
TIBCO Software
wdunlap tibco.com
On Mon, Jan 8, 2018 at 8:55 AM, Ek Esawi <esawiek at gmail.com> wrote:

            

  
  
#
Thank you all. Now everything works. Happy 2018 and beyond
EK
On Sun, Jan 7, 2018 at 10:13 PM, Ek Esawi <esawiek at gmail.com> wrote:
#
Hi

Yes, that is why I mentioned "the example". Of course if there are missing values in other columns or data layout is different, na.locf could give undesired result.

However it is simple and works with data similar to the example.

Cheers
Petr
________________________________
Tento e-mail a jak?koliv k n?mu p?ipojen? dokumenty jsou d?v?rn? a jsou ur?eny pouze jeho adres?t?m.
Jestli?e jste obdr?el(a) tento e-mail omylem, informujte laskav? neprodlen? jeho odes?latele. Obsah tohoto emailu i s p??lohami a jeho kopie vyma?te ze sv?ho syst?mu.
Nejste-li zam??len?m adres?tem tohoto emailu, nejste opr?vn?ni tento email jakkoliv u??vat, roz?i?ovat, kop?rovat ?i zve?ej?ovat.
Odes?latel e-mailu neodpov?d? za eventu?ln? ?kodu zp?sobenou modifikacemi ?i zpo?d?n?m p?enosu e-mailu.

V p??pad?, ?e je tento e-mail sou??st? obchodn?ho jedn?n?:
- vyhrazuje si odes?latel pr?vo ukon?it kdykoliv jedn?n? o uzav?en? smlouvy, a to z jak?hokoliv d?vodu i bez uveden? d?vodu.
- a obsahuje-li nab?dku, je adres?t opr?vn?n nab?dku bezodkladn? p?ijmout; Odes?latel tohoto e-mailu (nab?dky) vylu?uje p?ijet? nab?dky ze strany p??jemce s dodatkem ?i odchylkou.
- trv? odes?latel na tom, ?e p??slu?n? smlouva je uzav?ena teprve v?slovn?m dosa?en?m shody na v?ech jej?ch n?le?itostech.
- odes?latel tohoto emailu informuje, ?e nen? opr?vn?n uzav?rat za spole?nost ??dn? smlouvy s v?jimkou p??pad?, kdy k tomu byl p?semn? zmocn?n nebo p?semn? pov??en a takov? pov??en? nebo pln? moc byly adres?tovi tohoto emailu p??padn? osob?, kterou adres?t zastupuje, p?edlo?eny nebo jejich existence je adres?tovi ?i osob? j?m zastoupen? zn?m?.

This e-mail and any documents attached to it may be confidential and are intended only for its intended recipients.
If you received this e-mail by mistake, please immediately inform its sender. Delete the contents of this e-mail with all attachments and its copies from your system.
If you are not the intended recipient of this e-mail, you are not authorized to use, disseminate, copy or disclose this e-mail in any manner.
The sender of this e-mail shall not be liable for any possible damage caused by modifications of the e-mail or by delay with transfer of the email.

In case that this e-mail forms part of business dealings:
- the sender reserves the right to end negotiations about entering into a contract in any time, for any reason, and without stating any reasoning.
- if the e-mail contains an offer, the recipient is entitled to immediately accept such offer; The sender of this e-mail (offer) excludes any acceptance of the offer on the part of the recipient containing any amendment or variation.
- the sender insists on that the respective contract is concluded only upon an express mutual agreement on all its aspects.
- the sender of this e-mail informs that he/she is not authorized to enter into any contracts on behalf of the company except for cases in which he/she is expressly authorized to do so in writing, and such authorization or power of attorney is submitted to the recipient or the person represented by the recipient, or the existence of such authorization is known to the recipient of the person represented by the recipient.