Requesting Monthly Bloomberg Data with Rblpapi Options

# Change periodicity on Rblpapi


# Change periodicity on Rblpapi












So Dirk Eddelbuettel, Whit Armstrong, and John Laing released Rblpapi to CRAN recently, and it is awesome. I'm having some difficulty understanding how the overrides work though, hopefully someone can help me out.

I'm trying to import price returns from two indices, and want to do so using monthly data. W/out the periodicity override, it imports daily data fine. When I try and add an override to convert it to monthly data requests, I get an error. In the python api the override command is periodicity. Is it the same in Rblpapi? Does anyone know how this is this designed to work in Rblpapi? Are the override names and values the same as in the BBG developer's guide?

Here is a code sample and the resulting output:

```
library(Rblpapi)

#initalize data import
end.dt = Sys.Date()
start.dt = as.Date(x = "1995-03-31") #define start date

blpConnect() #connect to BBG, does not need to be closed

#set import variables
index.growth = "MXUS000G Index" #define growth index
index.value = "MXUS000V Index" #define value index

indices = c(index.growth,index.value)

overrides.px = "Monthly"
names(overrides.px) = "periodicity"

px = bdh(securities = indices,fields = "px_last",start.date = start.dt,end.date = end.dt,
         overrides = overrides.px)

Error: Choice sub-element not found for name 'securityData'.
```

Thanks!

## Answer by Dirk Eddelbuettel (score 6, accepted)

https://quant.stackexchange.com/a/19368

At first we considered it to be a bug where the `overrides` does not propagate correctly.

Edit: Here is a corrected examples, thanks to @Sid. Setting it as an `options` field works:

```
library(Rblpapi)
blpConnect()

## initalize data import
end.dt <- Sys.Date()
start.dt <- end.dt - 100  # keep it simple for example

index.growth <- "MXUS000G Index" #define growth index
index.value <- "MXUS000V Index" #define value index
indices <- c(index.growth,index.value)

overrides.px <- structure("MONTHLY", names=c"periodicitySelection")
px <- bdh(indices,"px_last",start.dt, end.dt, options = overrides.px)
print(px)
```

which works as you'd expect:

```
$ r /tmp/periodicity.R 
$`MXUS000G Index`
        date px_last
1 2015-05-29 3456.53
2 2015-06-30 3410.59
3 2015-07-31 3517.17

$`MXUS000V Index`
        date px_last
1 2015-05-29 2169.20
2 2015-06-30 2108.77
3 2015-07-31 2121.89

$
```

(As an aside, we suggest to file bug reports etc over at GitHub. You got lucky that I saw this...)

## Answer by Sid (score 6)

https://quant.stackexchange.com/a/19371

You're setting an option, not an override. Your code works fine if you replace

```
names(overrides.px) = "periodicity"
px = bdh(securities = indices,fields = "px_last",start.date = start.dt,end.date = end.dt,
     overrides = overrides.px)
```

with

```
names(overrides.px) = "periodicitySelection"
px = bdh(securities = indices,fields = "px_last",start.date = start.dt,end.date = end.dt,
     options = overrides.px)
```