Can I use ALTER TYPE for F8 to SDATE10 ?

[Ruben Geert van den Berg]

Dear all,

I've a numeric variable that I'd like to convert to a date. Its format is yyyymmdd (F8). For example

data list free/date(f8)time(f6).
begin data
20111030        232005
end data.

I thought I could convert it to a proper date using

alter type date(sdate10).

but that results in June 3rd, 1583, which is the exact same outcome as using

format date(sdate10).

instead of an ALTER TYPE command. So no real conversion took place, just a change in representation. Can't I use ALTER TYPE at all in this case? I know I can use

compute newdate=date.dmy(num(subs(str(date,f8),7,2),f2),num(subs(str(date,f8),5,2),f2),num(subs(str(date,f8),1,4),f4)).

but I thought that was deprecated after ALTER TYPE was introduced.

TIA!

[Jon K Peck]

ALTER TYPE could not do the conversion you want, because the actual input date format is unknown.  You want sdate10 as the result, but the input is just an F formatted value, so the actual value would have to already be an SPSS date value, which it is not in this case.

Date values are a numeric fundamental type, and the format command is just a display specification.


Jon Peck (no "h") aka Kim
Senior Software Engineer, IBM
[hidden email]
phone: [phone]




From:        Ruben Geert van den Berg <[hidden email]>
To:        [hidden email],
Date:        05/15/2013 11:26 PM
Subject:        [SPSSX-L] Can I use ALTER TYPE for F8 to SDATE10 ?
Sent by:        "SPSSX(r) Discussion" <[hidden email]>

---

Dear all,

I've a numeric variable that I'd like to convert to a date. Its format is
yyyymmdd (F8). For example

data list free/date(f8)time(f6).
begin data
20111030        232005
end data.

I thought I could convert it to a proper date using

alter type date(sdate10).

but that results in June 3rd, 1583, which is the exact same outcome as using

format date(sdate10).

instead of an ALTER TYPE command. So no real conversion took place, just a
change in representation. Can't I use ALTER TYPE at all in this case? I know
I can use

compute
newdate=date.dmy(num(subs(str(date,f8),7,2),f2),num(subs(str(date,f8),5,2),f2),num(subs(str(date,f8),1,4),f4)).

but I thought that was deprecated after ALTER TYPE was introduced.

TIA!



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[ViAnn Beadle]

Too little time to fire up version 21 but I thought if you read a date in as
a date you can just give it a different format via the format command? IIRC,
ALTER TYPE is used to quickly convert strings to numbers and vice versa.

-----Original Message-----
From: SPSSX(r) Discussion [mailto:[hidden email]] On Behalf Of
Ruben Geert van den Berg
Sent: Wednesday, May 15, 2013 11:18 PM
To: [hidden email]
Subject: Can I use ALTER TYPE for F8 to SDATE10 ?

Dear all,

I've a numeric variable that I'd like to convert to a date. Its format is
yyyymmdd (F8). For example

data list free/date(f8)time(f6).
begin data
20111030        232005
end data.

I thought I could convert it to a proper date using

alter type date(sdate10).

but that results in June 3rd, 1583, which is the exact same outcome as using

format date(sdate10).

instead of an ALTER TYPE command. So no real conversion took place, just a
change in representation. Can't I use ALTER TYPE at all in this case? I know
I can use

compute
newdate=date.dmy(num(subs(str(date,f8),7,2),f2),num(subs(str(date,f8),5,2),f
2),num(subs(str(date,f8),1,4),f4)).

but I thought that was deprecated after ALTER TYPE was introduced.

TIA!



--
View this message in context:
http://spssx-discussion.1045642.n5.nabble.com/Can-I-use-ALTER-TYPE-for-F8-to
-SDATE10-tp5720276.html
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=====================
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[hidden email] (not to SPSSX-L), with no body text except the
command. To leave the list, send the command SIGNOFF SPSSX-L For a list of
commands to manage subscriptions, send the command INFO REFCARD

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[Art Kendall]

Dates are represented as seconds since the start of the Gregorian calendar.
I use low number such as 1 day (86400) as a missing data value.

I recently asked for newer ways to go from A6 to a date.  see the archives for
 "6 character number to SPSS date"

The example syntax below show the some data formatting.

new file.
data list free/mydate(f8).
begin data
20111030
86400
1
end data.
alter type mydate(sdate10).
list.
data list free /actualdate (sdate10).
begin data
2011/10/30
2011/10/31
end data.
alter type actualdate (adate11).
list.
alter type actualdate (date11).
list.
alter type actualdate (f16).
list.

On 5/16/2013 1:17 AM, Ruben Geert van den Berg [via SPSSX Discussion] wrote:

Dear all,

I've a numeric variable that I'd like to convert to a date. Its format is yyyymmdd (F8). For example

data list free/date(f8)time(f6).
begin data
20111030        232005
end data.

I thought I could convert it to a proper date using

alter type date(sdate10).

but that results in June 3rd, 1583, which is the exact same outcome as using

format date(sdate10).

instead of an ALTER TYPE command. So no real conversion took place, just a change in representation. Can't I use ALTER TYPE at all in this case? I know I can use

compute newdate=date.dmy(num(subs(str(date,f8),7,2),f2),num(subs(str(date,f8),5,2),f2),num(subs(str(date,f8),1,4),f4)).

but I thought that was deprecated after ALTER TYPE was introduced.

TIA!

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[David Marso]

Need to massage the input just a bit.
DATA LIST free/date(f8)time(f6).
BEGIN DATA
20111030        232005
END DATA.
ALTER TYPE  date (A10).
COMPUTE date=CONCAT(CHAR.SUBSTR(date,3,4),
                                     "-",
                                     CHAR.SUBSTR(DATE,7,2),
                                     "-",
                                     CHAR.SUBSTR(date,9)).
ALTER TYPE date(sdate10).
LIST.

      date   time

2011/10/30 232005


Number of cases read:  1    Number of cases listed:  1

Ruben Geert van den Berg wrote

Dear all,

I've a numeric variable that I'd like to convert to a date. Its format is yyyymmdd (F8). For example

data list free/date(f8)time(f6).
begin data
20111030        232005
end data.

I thought I could convert it to a proper date using

alter type date(sdate10).

but that results in June 3rd, 1583, which is the exact same outcome as using

format date(sdate10).

instead of an ALTER TYPE command. So no real conversion took place, just a change in representation. Can't I use ALTER TYPE at all in this case? I know I can use

compute newdate=date.dmy(num(subs(str(date,f8),7,2),f2),num(subs(str(date,f8),5,2),f2),num(subs(str(date,f8),1,4),f4)).

but I thought that was deprecated after ALTER TYPE was introduced.

TIA!

[Ruben Geert van den Berg]

OK, no shortcut here so far...

I was expecting "sdate10" to do the ALTER TYPE trick. As in "sdate10 means yyyy-mm-dd so then the first four digits must be interpreted as the year ... " and so on. Similarly to converting a string date ("2011-04-13").

@David: yeah, better indeed.