[R] replace character by numeric value

[Ben Bolker]

   The reason you're getting the result as character is that you have 
'side' as your alternative result in the second ifelse().  If "BUY" and 
"SELL" are the only options you might try

    ifelse(side == 'BUY', 1, ifelse(side == 'SELL', -1, NA))

or

    c(1,-1)[match(side, c("BUY", "SELL"))]

or

vals <- c(BUY=1, SELL = -1)
vals[side]


On 2023-09-29 9:21 a.m., Ebert,Timothy Aaron wrote:
> Does this work?
> mynewdf$side <- as.numeric(mynewdf$side)
> 
> This code would be the next line after your mutate.
> 
> TIm
> 
> -----Original Message-----
> From: R-help <r-help-bounces using r-project.org> On Behalf Of Enrico Schumann
> Sent: Thursday, September 28, 2023 3:13 AM
> To: arnaud gaboury <arnaud.gaboury using gmail.com>
> Cc: r-help <r-help using r-project.org>
> Subject: Re: [R] replace character by numeric value
> 
> [External Email]
> 
> On Wed, 27 Sep 2023, arnaud gaboury writes:
> 
>> I have two data.frames:
>>
>> mydf1 <- structure(list(symbol = "ETHUSDT", cummulative_quote_qty =
>> 1999.9122, side = "BUY", time = structure(1695656875.805, tzone = "",
>> class = c("POSIXct", "POSIXt"))), row.names = c(NA, -1L), class =
>> c("data.table",
>> "data.frame"))
>>
>> mydf2 <- structure(list(symbol = c("ETHUSDT", "ETHUSDT", "ETHUSDT"),
>> cummulative_quote_qty = c(1999.119408, 0, 2999.890985), side =
>> c("SELL", "BUY", "BUY"), time = structure(c(1695712848.487,
>> 1695744226.993, 1695744509.082), class = c("POSIXct", "POSIXt"
>> ), tzone = "")), row.names = c(NA, -3L), class = c("data.table",
>> "data.frame"))
>>
>> I use this line to replace 'BUY' by numeric 1 and 'SELL' by numeric -1
>> in
>> mydf1 and mydf2:
>> mynewdf <- mydf |> dplyr::mutate(side = ifelse(side == 'BUY', 1,
>> ifelse(side == 'SELL', -1, side)))
>>
>> This does the job but I am left with an issue: 1 and -1 are characters
>> for
>> mynewdf2 when it is numeric for mynewdf1. The result I am expecting is
>> getting numeric values.
>> I can't solve this issue (using as.numeric(1) doesn't work) and don't
>> understand why I am left with num for mynewdf1 and characters for mynewdf2.
>>
>>> mynewdf1 <- mydf1 |> dplyr::mutate(side = ifelse(side == 'BUY', 1,
>> ifelse(side == 'SELL', -1, side)))
>>> str(mynewdf1)
>> Classes 'data.table' and 'data.frame': 1 obs. of  4 variables:
>>   $ symbol               : chr "ETHUSDT"
>>   $ cummulative_quote_qty: num 2000
>>   $ side                 : num 1      <<<------
>>   $ time                 : POSIXct, format: "2023-09-25 17:47:55"
>>   - attr(*, ".internal.selfref")=<externalptr>
>>
>>> mynewdf2 <- mydf2 |> dplyr::mutate(side = ifelse(side == 'BUY', 1,
>> ifelse(side == 'SELL', -1, side)))
>>>   str(mynewdf2)
>> Classes 'data.table' and 'data.frame': 3 obs. of  4 variables:
>>   $ symbol               : chr  "ETHUSDT" "ETHUSDT" "ETHUSDT"
>>   $ cummulative_quote_qty: num  1999 0 3000
>>   $ side                 : chr  "-1" "1" "1"   <<<------
>>   $ time                 : POSIXct, format: "2023-09-26 09:20:48"
>> "2023-09-26 18:03:46" "2023-09-26 18:08:29"
>>   - attr(*, ".internal.selfref")=<externalptr>
>>
>> Thank you for help
>>
> 
> I'd use something like this:
> 
>      map <- c(BUY = 1, SELL = -1)
>      mydf1$side <- map[mydf1$side]
>      str(mydf1)
>      ## Classes 'data.table' and 'data.frame':   1 obs. of  4 variables:
>      ##  $ symbol               : chr "ETHUSDT"
>      ##  $ cummulative_quote_qty: num 2000
>      ##  $ side                 : num 1
> 
>      mydf2$side <- map[mydf2$side]
>      str(mydf2)
>      ## Classes 'data.table' and 'data.frame':   3 obs. of  4 variables:
>      ##  $ symbol               : chr  "ETHUSDT" "ETHUSDT" "ETHUSDT"
>      ##  $ cummulative_quote_qty: num  1999 0 3000
>      ##  $ side                 : num  -1 1 1
>      ##  $ time                 : POSIXct, format: "2023-09-26 09:20:48" ...
> 
> 
> 
> --
> Enrico Schumann
> Lucerne, Switzerland
> http://enricoschumann.net/
> 
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-- 
Dr. Benjamin Bolker
Professor, Mathematics & Statistics and Biology, McMaster University
Director, School of Computational Science and Engineering
(Acting) Graduate chair, Mathematics & Statistics
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