merged data frame with <NA>

day_1 <- as.POSIXct("2005-11-14-00-00", format="%Y-%m-%d-%H-%M",

day_2 <- as.POSIXct("2005-11-14-12-00", format="%Y-%m-%d-%H-%M",

df2 <- data.frame(data_POSIX=seq(day_1, day_2, by="30 min"))



df1 <- data.frame(

df3 <- merge(df2, df1, by=c("data_POSIX"), all.x=TRUE)
df3

Hi Stefano,

For the merge() part, I'll leave it to more expert users (I rarely use
merge(), and every time I need it, it's painful...).

To know why <NA> instead of NA, check the results with str(df3); I guess
it is not the mode you expected.

For more details, you should provide the file, or better a reproducible
example using dput().

For the second part, your syntax was not correct (subsetting a column
for elements based on a column that is not part of the subset!). And
there is no column "pch" in your example. Try:
df3[df3$event == "start", "event"] <- 24

HTH,
Ivan

--
Dr. Ivan Calandra
TraCEr, laboratory for Traceology and Controlled Experiments
MONREPOS Archaeological Research Centre and
Museum for Human Behavioural Evolution
Schloss Monrepos
56567 Neuwied, Germany
+49 (0) 2631 9772-243
https://www.researchgate.net/profile/Ivan_Calandra

On 29/09/2020 9:59, Stefano Sofia wrote:

Dear R users,
I'm struggling with a simple "merge".

I have an external file called df.txt like

data_POSIX, event
2005-11-14 02:30:00, "start"
2005-11-14 11:30:00, "end"

I load it with

df1 <- read.table(file="df.txt", header=TRUE, sep=",", dec = ".",

stringsAsFactors=FALSE)

df1$data_POSIX <- as.POSIXct(df1$data_POSIX, format="%Y-%m-%d %H:%M:%S",

tz="Etc/GMT-1")

Then I create a new data frame df2:

day_1 <- as.POSIXct("2005-11-14-00-00", format="%Y-%m-%d-%H-%M",

tz="Etc/GMT-1")

day_2 <- as.POSIXct("2005-11-14-12-00", format="%Y-%m-%d-%H-%M",

tz="Etc/GMT-1")

df2 <- data.frame(data_POSIX=seq(day_1, day_2, by="30 min"))

Finally

df3 <- merge(df2, df1, by=c("data_POSIX"), all.x=TRUE)

gives

            data_POSIX event
1  2005-11-14 00:00:00    <NA>
2  2005-11-14 00:30:00    <NA>
3  2005-11-14 01:00:00    <NA>
4  2005-11-14 01:30:00    <NA>
5  2005-11-14 02:00:00    <NA>
6  2005-11-14 02:30:00  start
7  2005-11-14 03:00:00    <NA>
8  2005-11-14 03:30:00    <NA>
9  2005-11-14 04:00:00    <NA>
10 2005-11-14 04:30:00    <NA>
11 2005-11-14 05:00:00    <NA>
12 2005-11-14 05:30:00    <NA>
13 2005-11-14 06:00:00    <NA>
14 2005-11-14 06:30:00    <NA>
15 2005-11-14 07:00:00    <NA>
16 2005-11-14 07:30:00    <NA>
17 2005-11-14 08:00:00    <NA>
18 2005-11-14 08:30:00    <NA>
19 2005-11-14 09:00:00    <NA>
20 2005-11-14 09:30:00    <NA>
21 2005-11-14 10:00:00    <NA>
22 2005-11-14 10:30:00    <NA>
23 2005-11-14 11:00:00    <NA>
24 2005-11-14 11:30:00    end
25 2005-11-14 12:00:00    <NA>

Why there is <NA> instead of NA?
And why

df3$pch[df3$event == "start"] <- 24

gives a whole column of NA and not 24 at row 6?


          (oo)
--oOO--( )--OOo----------------
Stefano Sofia PhD
Civil Protection - Marche Region
Meteo Section
Snow Section
Via del Colle Ameno 5
60126 Torrette di Ancona, Ancona
Uff: 071 806 7743
E-mail: stefano.sofia at regione.marche.it
---Oo---------oO----------------

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