About size of data frames

Rui, et. al. :
"real results probably depend on the functions
you want to apply to the data."

Indeed!
I would presume that one would want to analyze such data as time series of
some sort, for which I think long form is inherently "more sensible". If
so, I also would think that you would want columns for data, sensor*,
season, and day, as Rui suggested.  However, note that this presumes no
missing data, which is usually wrong. To handle this, within each day the
rows would need to be in order of the hour the data was recorded (I assume
twice per hour) with a missing code when data was missing.

*As an aside, whether <data, season, day> data is in the form of a single
data frame with an additional sensor ID column or a list of 70 frames, one
for each sensor,  is not really much of an issue these days, where
gigabytes and gigaflops are cheap and available, as it is trivial to
convert from one form to another as needed.

Feel free to disagree -- I am just amplifying Rui's comment above; "what I
would presume" and "what I think" doesn't matter. What matters is Stefano's
response to his comment.

Cheers,
Bert

On Thu, Aug 14, 2025 at 10:54?AM Rui Barradas <ruipbarradas at sapo.pt> wrote:

On 8/14/2025 12:27 PM, Stefano Sofia via R-help wrote:

Dear R-list users,

let me ask you a very general question about performance of big data

frames.

I deal with semi-hourly meteorological data of about 70 sensors during

28 winter seasons.

It means that for each sensor I have 48 data for each day, 181 days for

each winter season (182 in case of leap year): 48 * 181 * 28 = 234,576

234,576 * 70 = 16420320


 From the computational point of view it is better to deal with a single

data frame of approximately 16.5 M rows and 3 columns (one for data, one
for sensor code and one for value), with a single data frame of
approximately 235,000 rows and 141 rows or 70 different data frames of
approximately 235,000 rows and 3 rows? Or it doesn't make any difference?

I personally would prefer the first choice, because it would be easier

for me to deal with a single data frame and few columns.

Thank you for your usual help

Stefano


          (oo)
--oOO--( )--OOo--------------------------------------
Stefano Sofia MSc, PhD
Civil Protection Department - Marche Region - Italy
Meteo Section
Snow Section
Via Colle Ameno 5
60126 Torrette di Ancona, Ancona (AN)
Uff: +39 071 806 7743
E-mail: stefano.sofia at regione.marche.it
---Oo---------oO----------------------------------------

informazioni confidenziali, pertanto ? destinato solo a persone autorizzate
alla ricezione. I messaggi di posta elettronica per i client di Regione
Marche possono contenere informazioni confidenziali e con privilegi legali.
Se non si ? il destinatario specificato, non leggere, copiare, inoltrare o
archiviare questo messaggio. Se si ? ricevuto questo messaggio per errore,
inoltrarlo al mittente ed eliminarlo completamente dal sistema del proprio
computer. Ai sensi dell'art. Ai sensi dell'art. 2.4 dell'allegato 1 alla
DGR n. 74/2021, si segnala che, in caso di necessit? ed urgenza, la
risposta al presente messaggio di posta elettronica pu? essere visionata da
persone estranee al destinatario.

IMPORTANT NOTICE: This e-mail message is intended to be received only by

persons entitled to receive the confidential information it may contain.
E-mail messages to clients of Regione Marche may contain information that
is confidential and legally privileged. Please do not read, copy, forward,
or store this message unless you are an intended recipient of it. If you
have received this message in error, please forward it to the sender and
delete it completely from your computer system.

      [[alternative HTML version deleted]]

[[alternative HTML version deleted]]