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Maintaining Column names while writing csv file.

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Vincy Pyne

Maintaining Column names while writing csv file.

Dear R helpers,

I have one trivial problem while writing an output file in csv format.

I have two dataframes say df1 and df2 which I am reading from two different csv files.

df1 has column names as date, r1, r2, r3 while the dataframe df2 has column names as date, 1w, 2w.

(the dates in both the date frames are identical also no of elements in each column are equal say = 10).

I merge these dataframes as

df_new = merge(df1, df2, by = "date", all = T)

So my new data frame has columns as

date, r1, r2, r3, 1w, 2w

However, if I try to write this new dataframe as a csv file as

write.csv(data.frame(df_new), 'df_new.csv', row.names = FALSE)

The file gets written, but when I open the csv file, the column names displayed are as

date, r1, r2, r3, X1w, X2w

My original output file has about 200 columns so it is not possible to write column names individually. Also, I can't change the column names since I am receiving these files from external source and need to maintain the column names.

Kindly guide

Regards

Vincy

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Eik Vettorazzi-2

Re: Maintaining Column names while writing csv file.

Hi Vincy,
have you checked

names(df2)

and

names(df_new)

because by default 'data.frame' checks the column names "to ensure that
they are syntactically valid variable names" and 1w and 2w aren't, so an
X is prepended (see ?data.frame and ?make.names).

compare
tst.fail<-data.frame(a=1:3,"1a"=1:3,"1b"=1:3)
names(tst.fail)

#and
tst<-data.frame(a=1:3,"1a"=1:3,"1b"=1:3,check.names = F)
names(tst)

this works for me:

tst2<-data.frame(a=1:3,w1=4:6,w3=4:6)
write.csv(merge(tst,tst2),file="testr.csv")

hth.

Am 19.07.2012 08:55, schrieb Vincy Pyne:

> Dear R helpers,
>
> I have one trivial problem while writing an output file in csv format.
>
> I have two dataframes say df1 and df2 which I am reading from two different csv files.
>
> df1 has column names as date, r1, r2, r3 while the dataframe df2 has column names as date, 1w, 2w.
>
> (the dates in both the date frames are identical also no of elements in each column are equal say = 10).
>
> I merge these dataframes as
>
> df_new = merge(df1, df2, by = "date", all = T)
>
> So my new data frame has columns as
>
> date, r1, r2, r3, 1w, 2w
>
> However, if I try to write this new dataframe as a csv file as
>
> write.csv(data.frame(df_new), 'df_new.csv', row.names = FALSE)
>
> The file gets written, but when I open the csv file, the column names displayed are as
>
> date, r1, r2, r3, X1w, X2w
>
> My original output file has about 200 columns so it is not possible to write column names individually. Also, I can't change the column names since I am receiving these files from external source and need to maintain the column names.
>
> Kindly guide
>
>
> Regards
>
> Vincy
>
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> [hidden email] mailing list
> 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.
>

--
Eik Vettorazzi

Department of Medical Biometry and Epidemiology
University Medical Center Hamburg-Eppendorf

Martinistr. 52
20246 Hamburg

T ++49/40/7410-58243
F ++49/40/7410-57790

--
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Rolf Turner-3

Re: Maintaining Column names while writing csv file.

In reply to this post by Vincy Pyne

On 19/07/12 18:55, Vincy Pyne wrote:

Just omit the unnecessary and redundant call to data.frame()
inside your call to write.csv(). I.e. just do:

write.csv(df_new, 'df_new.csv', row.names = FALSE)

It is that call to data.frame() that is forcing legal names
on you, *not* the call to write.csv().

cheers,

Rolf Turner

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arun kirshna

Re: Maintaining Column names while writing csv file.

In reply to this post by Vincy Pyne

HI,

Possibly check.names=FALSE issue.

Try this:
dat1<-read.table(text="
2.5a 3.6b 7.1c 7.9d
100 3      4      2    3
200 3.1 4      3      3
300 2.2 3.3 2    4
",sep="",header=TRUE)
dat1
#You can get rid of those X by either using check.names=FALSE while reading the data

#with check.names=FALSE

dat1<-read.table(text="
2.5a 3.6b 7.1c 7.9d
100 3      4      2    3
200 3.1 4      3      3
300 2.2 3.3 2    4
",sep="",header=TRUE,check.names=FALSE)

dat1

#or before write.csv()
colnames(dat1)<-gsub("^[X](.*)","\\1",colnames(dat1))

A.K.

----- Original Message -----
From: Vincy Pyne <[hidden email]>
To: [hidden email]
Cc:
Sent: Thursday, July 19, 2012 2:55 AM
Subject: [R] Maintaining Column names while writing csv file.

Dear R helpers,

I have one trivial problem while writing an output file in csv format.

I have two dataframes say df1 and df2 which I am reading from two different csv files.

df1 has column names as date, r1, r2, r3 while the dataframe df2 has column names as date, 1w, 2w.

(the dates in both the date frames are identical also no of elements in each column are equal say = 10).

I merge these dataframes as

df_new = merge(df1, df2, by = "date", all = T)

So my new data frame has columns as

date, r1, r2, r3, 1w, 2w

However, if I try to write this new dataframe as a csv file as

write.csv(data.frame(df_new), 'df_new.csv', row.names = FALSE)

The file gets written, but when I open the csv file, the column names displayed are as

date, r1, r2, r3, X1w, X2w

My original output file has about 200 columns so it is not possible to write column names individually. Also, I can't change the column names since I am receiving these files from external source and need to maintain the column names.

Kindly guide

Regards

Vincy

    [[alternative HTML version deleted]]

______________________________________________
[hidden email] mailing list
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
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.