switch to xts

DESCRIPTION

@@ -1,6 +1,6 @@
 Package: fredr
 Title: Interact with the FRED API in the R workspace
-Version: 0.2.0.0
+Version: 0.3.0.0
 Authors@R: person("Sam", "Boysel", email = "sboysel@gmail.com", role = c("aut", "cre"))
 Description: Wrap the FRED API with httr and dplyr to quickly bring data from
 	     FRED into the R workspace.
@@ -10,10 +10,12 @@ Depends:
   R (>= 3.2.2)
 Imports: 
   httr,
-  dplyr
+  dplyr,
+  xts
 Suggests:
   ggfortify,
-  testthat
+  testthat,
+  zoo
 License: MIT + file LICENSE 
 LazyData: true
-RoxygenNote: 5.0.1
+RoxygenNote: 6.0.1

Makefile

@@ -1,4 +1,4 @@
-R=/usr/bin/R
+R=/usr/local/bin/R
 
 all: knit
 

NAMESPACE

@@ -5,4 +5,3 @@ export(fredr_docs)
 export(fredr_key)
 export(fredr_search)
 export(fredr_series)
-export(get_freq)

R/fredr.R

@@ -9,7 +9,7 @@
 #'        should be parsed and formatted as a tbl_df.  Default is TRUE.
 #' @param print_req A boolean value indicating whether or not the request
 #'        should be printed as well.  Useful for debugging.
-#' @return A tbl_df.  If to_frame is TRUE, return is a reponse object from 
+#' @return A tbl_df.  If to_frame is TRUE, return is a reponse object from
 #'        httr::GET().
 #' @examples
 #'  fredr("series/observations",
@@ -18,23 +18,29 @@
 #'        observation_end = "2000-01-01")
 #' @export
 fredr <- function(endpoint, ..., to_frame = TRUE, print_req = FALSE) {
-  params <- list(...)
+
   if (identical(Sys.getenv("FRED_API_KEY"), "")) {
     stop("FRED API key must be set.  Use fredr_key()")
   }
+
+  params <- list(...)
   params$api_key <- Sys.getenv("FRED_API_KEY")
   params$file_type <- "json"
+
   resp <- httr::GET(url = "https://api.stlouisfed.org/",
                     path = paste0("fred/", endpoint),
                     query = params)
-  if (print_req == TRUE) {
+
+  if (print_req) {
     message(resp$url)
   }
+
   if (resp$status_code != 200) {
     err <- httr::content(resp)
     stop(paste0(err$error_code, ": ", err$error_message))
   }
-  if (to_frame == TRUE) {
+
+  if (to_frame) {
     parsed <- httr::content(resp)
     if (endpoint %in% c("category",
                         "category/children",

R/fredr_docs.R

@@ -1,13 +1,13 @@
 #' Open the web documentation for a certain FRED API topic.
 #'
-#' @param endpoint A string representing the desired documentation for the exact 
+#' @param endpoint A string representing the desired documentation for the exact
 #'				FRED API endpoint.  Default is 'base' and will open a link to
 #'				https://api.stlouisfed.org/docs/fred/.
 #' @param params A boolean value.  If TRUE, the documentation will be opened at
 #'        the 'Paramters' section.  Default is FALSE.
 #' @param debug A boolean value.  If TRUE, the documentation is not opened in a
 #'        browser.  Default is FALSE.
-#' @examples 
+#' @examples
 #' fredr_docs()
 #' fredr_docs('category')
 #' fredr_docs('series/observations')
@@ -54,6 +54,6 @@ fredr_docs <- function(endpoint = "base", params = FALSE, debug = FALSE) {
     doc <- paste0(doc, "#Parameters")
   }
   if (!debug) {
-    browseURL(url = doc)
+    utils::browseURL(url = doc)
   }
 }

R/fredr_search.R

@@ -1,13 +1,13 @@
 #' Search for a FRED series.
 #'
-#' @param ... A series of paramters to be used in the query.  Of the form 
-#' param_key = 'param_value'.  The parameter \code{search_text} is required for 
-#' \code{series/search} and \code{series_search_text} is required for 
+#' @param ... A series of paramters to be used in the query.  Of the form
+#' param_key = 'param_value'.  The parameter \code{search_text} is required for
+#' \code{series/search} and \code{series_search_text} is required for
 #' \code{series/search/tags} or \code{series/search/related_tags}.
-#' @param search_field A string indicating to search for a series, series tags, 
+#' @param search_field A string indicating to search for a series, series tags,
 #' or related series tags.  Default is "series" to search for a series.  Use
 #' "tags" to search tags and "related_tags" to search related tags.
-#' @return A \code{ts} object.
+#' @return A \code{data.frame} object.
 #' @examples
 #' fredr_search(search_text = "oil", order_by = "popularity")
 #' @export

R/fredr_series.R

@@ -1,9 +1,9 @@
-#' Return a FRED dataset as a time series object.
+#' Return a FRED dataset as an \code{xts} object.
 #'
 #' @param ... A series of paramters to be used in the query.  Of the form
 #'        param_key = 'param_value'.  The parameter \code{series_id} is
 #'        required.
-#' @return A \code{ts} object.
+#' @return An \code{xts} object.
 #' @examples
 #' fredr_series(series_id = "UNRATE",
 #'              observation_start = "1980-01-01",
@@ -15,58 +15,27 @@
 #'              unit = "log")
 #' @export
 fredr_series <- function(...) {
+
   params <- list(...)
+
   if (!("series_id" %in% names(params))) {
     stop("Missing 'series_id' parameter.")
   }
-  if ("frequency" %in% names(params)) {
-    freq <- switch(params[["frequency"]],
-                 "d" = 365,
-                 "w" = 52,
-                 "bw" = 26,
-                 "m" = 12,
-                 "q" = 4,
-                 "sq" = 2,
-                 "a" = 1)
-    if (is.null(freq)) {
-      stop("Invalid 'frequency' value supplied.")
-    }
-  } else {
-    freq <- switch(fredr::get_freq(params[["series_id"]]),
-                   "Daily" = 365,
-                   "Weekly" = 52,
-                   "Bi-Weekly" = 26,
-                   "Monthly" = 12,
-                   "Quarterly" = 4,
-                   "Semiannual" = 2,
-                   "Annual" = 1)
-  }
+
   frame <- fredr::fredr(endpoint = "series/observations", ...)
+
   frame$value[frame$value == "."] <- NA
   frame$value <- as.numeric(frame$value)
   frame$date <- as.Date(frame$date, "%Y-%m-%d")
-  y <- as.numeric(format(frame$date[1], "%Y"))
-  m <- as.numeric(format(frame$date[1], "%m"))
-  d <- as.numeric(format(frame$date[1], "%d"))
-  series <- ts(data = frame$value,
-               start = c(y, m, d),
-               frequency = freq)
-  return(series)
-}
 
-#' Check the default frequency of a series with a call to the FRED API
-#'
-#' @param series_id A string
-#' @return An integer representing the number of series observations in a unit 
-#'         of time.  Used in creating a \code{ts} object with the appropriate 
-#'         temporal frequency.
-#' @examples
-#'  get_freq(series_id = "GNPCA")
-#' @export
-get_freq <- function(series_id){
-  if (is.null(series_id)) {
-    stop("series_id parameter not present.")
-  }
-  freq <- fredr::fredr("series", series_id = series_id)$frequency
-  return(freq)
+  frame <- frame[order(frame$date), ]
+
+  series <- xts::xts(
+    x = frame$value,
+    order.by = frame$date
+  )
+
+  names(series) <- params[["series_id"]]
+
+  return(series)
 }

README.Rmd

@@ -22,9 +22,9 @@ Reserve Bank of St. Louis.  Essentially a simple wrapper of
 [`httr`](https://github.com/hadley/httr),
 [`dplyr`](https://github.com/hadley/dplyr), and the FRED API itself, `fredr` is
 designed with simplicity and flexibility in mind.  In addition a generic query
-function `fredr` to return any query as a `tbl_df`, the package also provides
+function `fredr` to return any query as a `data.frame`, the package also provides
 convenience functions `fredr_search` and `fredr_series` to simplify the process
-to finding and importing FRED series as `R` objects.  As nearly all optional
+to finding and importing FRED data series as `R` objects.  As nearly all optional
 parameters supplied to these functions are relayed verbatim to the API, the 
 user is strongly encouraged to read the full [FRED
 API](https://research.stlouisfed.org/docs/api/fred/) to leverage the full power
@@ -36,7 +36,7 @@ examples.
 # install.packages("devtools")
 devtools::install_github("sboysel/fredr")
 ```
-## Quickstart
+## Usage
 Load `fredr`
 ```{r load_libi, eval=FALSE}
 library(fredr)
@@ -52,47 +52,38 @@ Search for FRED series
 ```{r fredr_search, message=FALSE, warning=FALSE}
 fredr_search(search_text = "housing")
 ```
-Get a FRED series.  Returns a `ts` object.
+Get a FRED series.  Returns an `xts` object.
 ```{r fredr_series1, message=FALSE, warning=FALSE}
-fredr_series(series_id = "HOUST",
-             observation_start = "1990-01-01",
-             observation_end = "1995-01-01")
+library(dplyr)
+library(xts)
+fredr_series(series_id = "UNRATE",
+             observation_start = "1990-01-01") %>%
+    window(., start = "1990-01-01", end = "1991-01-01")
 ```
-Leverage the native features of the FRED API
+Leverage the native features of the FRED API:
 ```{r fredr_series2, message=FALSE, warning=FALSE}
 fredr_series(series_id = "UNRATE",
              observation_start = "1990-01-01",
              frequency = "q",
-             units = "chg")
-```
-Combine with other packages for a slick workflow
-```{r fredr_series3, message=FALSE, warning=FALSE}
-library(dplyr)
-library(ggfortify)
-fredr_series(series_id = "GNPCA",
-             units = "log") %>%
-  autoplot()
-```
-```{r fredr_series4, message=FALSE, warning=FALSE}
-fredr_series(series_id = "GNPCA",
-             units = "log") %>%
-  diff() %>%
-  autoplot()
+             units = "chg") %>%
+    window(., start = "1990-01-01", end = "1991-01-01")
 ```
+
 ```{r fredr_series5, message=FALSE, warning=FALSE}
 fredr_series(series_id = "GNPCA",
              units = "log") %>%
   diff() %>%
+  na.omit() %>%
   StructTS() %>%
   residuals() %>%
   acf(., main = "ACF for First Differenced real US GNP, log")
 ```
 ```{r fredr_series6, message=FALSE, warning=FALSE}
 fredr_search(search_text = "federal funds",
-             order_by = "popularity") %>%
-  slice(1) %>%
-  fredr_series(series_id = .$id) %>%
-  window(., start = 2000, end = c(2000, 120))
+             order_by = "popularity",
+             limit = 1)$id %>%
+  fredr_series(series_id = .) %>%
+  plot(., main = "Federal Funds Rate")
 ```
 
 Quickly access the FRED API web documentation for any endpoint
@@ -116,6 +107,7 @@ fredr(endpoint = "tags/series", tag_names = "population;south africa")
 The primary goal in creating `fredr` was educational.  I also suggest you check
 out several other `R` packages designed for the FRED API:
 
+* [business-science/tidyquant](https://github.com/business-science/tidyquant)
 * [jcizel/FredR](https://github.com/jcizel/FredR)
 * [joshuaulrich/quantmod](https://github.com/joshuaulrich/quantmod)
 * [quandl/quandl-r](https://github.com/quandl/quandl-r)