hi, I practice R programing by the step in <<R In Action>>;
when i test by function, i get error like these;
call for help!
dstats <- function(x){c(mean=mean(x), sd=sd(x))}> by(mtcars[,c('mpg', 'hp')], mtcars$am, dstats)
Show Traceback
Rerun with Debug
Error in is.data.frame(x) :
(list) object cannot be coerced to type 'double'
------------------
BestRegards
Su Wenlong
Phone:13408010439
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Hi The problem is in your function, not in by.> dstats(mtcars[,c('mpg', 'hp')])Error in is.data.frame(x) : (list) object cannot be coerced to type 'double' In addition: Warning message: In mean.default(x) : argument is not numeric or logical: returning NA>Your function expects vector but you give it data frame and it cannot handle data frames. see str(by(mtcars[,c('mpg', 'hp')], mtcars$am, I)) List of 2 $ 0:Classes ?AsIs? and 'data.frame': 19 obs. of 2 variables: ..$ mpg: num [1:19] 21.4 18.7 18.1 14.3 24.4 22.8 19.2 17.8 16.4 17.3 ... ..$ hp : num [1:19] 110 175 105 245 62 95 123 123 180 180 ... $ 1:Classes ?AsIs? and 'data.frame': 13 obs. of 2 variables: ..$ mpg: num [1:13] 21 21 22.8 32.4 30.4 33.9 27.3 26 30.4 15.8 ... ..$ hp : num [1:13] 110 110 93 66 52 65 66 91 113 264 ... - attr(*, "dim")= int 2 - attr(*, "dimnames")=List of 1 ..$ mtcars$am: chr [1:2] "0" "1" - attr(*, "call")= language by.data.frame(data = mtcars[, c("mpg", "hp")], INDICES = mtcars$am, FUN = I) - attr(*, "class")= chr "by" You maybe should consult ?aggregate. Cheers. Petr -----Original Message----- From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of ??? Sent: Thursday, April 20, 2017 2:17 AM To: r-help <r-help at r-project.org> Subject: [R] by function error hi, I practice R programing by the step in <<R In Action>>; when i test by function, i get error like these; call for help! dstats <- function(x){c(mean=mean(x), sd=sd(x))}> by(mtcars[,c('mpg', 'hp')], mtcars$am, dstats)Show Traceback Rerun with Debug Error in is.data.frame(x) : (list) object cannot be coerced to type 'double' ------------------ BestRegards Su Wenlong Phone:13408010439 [[alternative HTML version deleted]] ______________________________________________ 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. ________________________________ 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.
I got it; thanks ------------------ BestRegards Su Wenlong Phone:13408010439 ------------------ ???? ------------------ ???: "PIKAL Petr";<petr.pikal at precheza.cz>; ????: 2017?4?21?(???) ??0:16 ???: "???"<814057409 at qq.com>; "r-help"<r-help at r-project.org>; ??: RE: [R] by function error Hi The problem is in your function, not in by.> dstats(mtcars[,c('mpg', 'hp')])Error in is.data.frame(x) : (list) object cannot be coerced to type 'double' In addition: Warning message: In mean.default(x) : argument is not numeric or logical: returning NA>Your function expects vector but you give it data frame and it cannot handle data frames. see str(by(mtcars[,c('mpg', 'hp')], mtcars$am, I)) List of 2 $ 0:Classes ?AsIs? and 'data.frame': 19 obs. of 2 variables: ..$ mpg: num [1:19] 21.4 18.7 18.1 14.3 24.4 22.8 19.2 17.8 16.4 17.3 ... ..$ hp : num [1:19] 110 175 105 245 62 95 123 123 180 180 ... $ 1:Classes ?AsIs? and 'data.frame': 13 obs. of 2 variables: ..$ mpg: num [1:13] 21 21 22.8 32.4 30.4 33.9 27.3 26 30.4 15.8 ... ..$ hp : num [1:13] 110 110 93 66 52 65 66 91 113 264 ... - attr(*, "dim")= int 2 - attr(*, "dimnames")=List of 1 ..$ mtcars$am: chr [1:2] "0" "1" - attr(*, "call")= language by.data.frame(data = mtcars[, c("mpg", "hp")], INDICES = mtcars$am, FUN = I) - attr(*, "class")= chr "by" You maybe should consult ?aggregate. Cheers. Petr -----Original Message----- From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of ??? Sent: Thursday, April 20, 2017 2:17 AM To: r-help <r-help at r-project.org> Subject: [R] by function error hi, I practice R programing by the step in <<R In Action>>; when i test by function, i get error like these; call for help! dstats <- function(x){c(mean=mean(x), sd=sd(x))}> by(mtcars[,c('mpg', 'hp')], mtcars$am, dstats)Show Traceback Rerun with Debug Error in is.data.frame(x) : (list) object cannot be coerced to type 'double' ------------------ BestRegards Su Wenlong Phone:13408010439 [[alternative HTML version deleted]] ______________________________________________ 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. ________________________________ 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. 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