Thank you to Sarah Goslee and Ivan Calandra for their exhaustive explanations.
About Ivan Calandra's suggestion to put data in the right format adding a
column "station" with values being
either RM or RT, I would ask Ivan if he means to divide the initial data frame
into two data frames, one for RM and one for RT.
If this is the case, then I would find a way to link the two data frames, and
this might not be the most efficient solution. But likely I miss the true
meaning of the comment.
Thank you
Stefano
----------------------------------------------------------------------------------------
>
> Message: 14
> Date: Wed, 7 Sep 2016 16:56:20 +0200
> From: Ivan Calandra <ivan.calan...@univ-reims.fr>
> To: r-help@r-project.org
> Subject: Re: [R] how to manage missing values correctly when importing
> a data frame
> Message-ID: <388bc333-497c-f806-e367-8aecb0a7d...@univ-reims.fr>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> Hi Stefano,
>
> I agree that this behavior of R can be somewhat counter-intuitive, but
> this can be seen as a safety procedure, so that no assumptions are made
> and problems can be easily identified.
>
> I would think that in this case, the input data is in the wrong format.
> Half the columns are for RM and the other for RT, but the headers are
> exactly the same. The problem then happens because you actually have
> only 3 lines of data for station RT but 4 for station RM. So it is
> filled with NA.
>
> IMHO, it would be better to add a column "station" with values being
> either RM or RT. In that case, you would not have whole NA lines. And
> you would have less columns to work with. See what I mean?
>
> By the way, I like the matrix method for subsetting a data.frame, I find
> it easier and more flexible (maybe someone will tell if there are any
> drawbacks):
> Storia_RM_RT[Storia_RM_RT$Station_RT==112, "Test_20151231"]
>
> HTH,
> Ivan
>
> --
> Ivan Calandra, PhD
> Scientific Mediator
> University of Reims Champagne-Ardenne
> GEGENAA - EA 3795
> CREA - 2 esplanade Roland Garros
> 51100 Reims, France
> +33(0)3 26 77 36 89
> ivan.calan...@univ-reims.fr
>
> ----------------------------------------------------------------------------------------
> Original Message:
>
> Dear R users,
> I have a data frame with 22 columns, called Storia_RM_RT. Here the first 4
> rows:
>
> Station_RM Sensor_RM Place_RM Y_init_RM M_init_RM D_init_RM Long_cent_RM
> Lat_cent_RM Height_RM Continues Station_RT Sensor_RT Place_RT Name1_RT
> Name2_RT Long_cent_RT Lat_cent_RT Height_RT Actual_net Notes
> Test_20141231 Test_20151231
> 1400 2701 Novafeltria 1959 1 1 12.289552 43.890057 293 NO NA NA NA NA NA NA
> NA NA CAE NA NO NO
> 1460 2702 Carpegna 1963 1 1 12.332614 43.778107 748 SI 702 2954 Carpegna
> Carpegna Carpegna 12.340618 43.780575 715 RT NA NO NO
> 1500 2703 Pesaro 1957 1 1 12.909822 43.910889 11 SI 112 1229 Pesaro
> Villa_Fastiggi Villa_Fastiggi 12.86939 43.890610 22 RT NA YES YES
> 1520 2704 Fano 1957 1 1 13.017591 43.840054 4 SI 152 2671 Fano Foce_Metauro
> Metaurilia 13.053796 43.826328 7.12 RT NA YES YES
>
> I load it with
> Storia_RM_RT <- read.table(file="Storia_RM_RT.txt", header = TRUE, sep=" ",
> dec = ".", stringsAsFactors = FALSE)
>
> print(Storia_RM_RT$Test_20151231[Storia_RM_RT$Station_RM == 1500]) gives
> [1] "YES"
>
> while
> print(Storia_RM_RT$Omogenea_20151231[Storia_RM_RT$Station_RT == 112]) gives
> [1] NA "YES"
>
>
> I am struggling to understand why the query through the field Station_RT does
> not work.
> Could please somebody help me to manage correctly the missing values? Is the
> mistake somewhere else?
>
> Thank you
> Stefano Sofia
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