Read Sheets

Source: vignettes/articles/read-sheets.Rmd 
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Basic Sheet reading is shown in the Get started article. Here we show how to target a specific (work)sheet or cell range, how to deal with column types, and how to get detailed cell data.

Auth

As a regular, interactive user, you can just let googlesheets4 prompt you for anything it needs re: auth.

Since this article is compiled noninteractively on a server, we have arranged for googlesheets4 to use a service account token (not shown).

read_sheet() and range_read() are synonyms

The main “read” function of the googlesheets4 package goes by two names, because we want it to make sense in two contexts:

  • read_sheet() evokes other table-reading functions, like readr::read_csv() and readxl::read_excel(). The sheet in this case refers to a Google (spread)Sheet.

  • range_read() is technically the right name according to the naming convention used throughout the googlesheets4 package, because we can read from an arbitrary cell range.

read_sheet() and range_read() are synonyms and you can use either one. Throughout this article, we’re going to use range_read().

Note: The first release of googlesheets used a sheets_ prefix everywhere, so we had sheets_read(). It still works, but it’s deprecated and will go away rather swiftly.

Specify the range and column types

Here we read from the “mini-gap” and “deaths” example Sheets to show some of the different ways to specify (work)sheet and cell ranges.

range_read(gs4_example("mini-gap"), sheet = 2)

range_read(gs4_example("mini-gap"), sheet = "Oceania", n_max = 3)

range_read(gs4_example("deaths"), skip = 4, n_max = 10)

The example below shows the use of range to specify both the (work)sheet and an A1-style cell range.

It also demonstrates how col_types gives control of column types, similar to how col_types works in readr and readxl. Note that currently there is only support for the “shortcode” style of column specification and we plan to align better with readr’s capabilities in a future release.

range_read(
  gs4_example("deaths"), range = "other!A5:F15", col_types = "?ci??D"
)

If you looked at the “deaths” spreadsheet in the browser (it’s here), you know that it has some of the typical features of real world spreadsheets: the main data rectangle has prose intended for human-consumption before and after it. That’s why we have to specify the range when we read from it.

We’ve designated the data rectangles as named ranges, which provides a very slick way to read them – definitely less brittle and mysterious than approaches like range = "other!A5:F15" or skip = 4, n_max = 10. A named range can be passed via the range = argument:

gs4_example("deaths") %>% 
  range_read(range = "arts_data")

The named ranges, if any exist, are part of the information returned by gs4_get().

Detailed cell data

range_read_cells() returns a data frame with one row per cell and it gives access to raw cell data sent by the Sheets API.

(df <- range_read_cells(gs4_example("deaths"), range = "E5:E7"))
df$cell[[3]]

Specify cell_data = "full", discard_empty = FALSE to get even more data if you, for example, need access to cell formulas or formatting.

spread_sheet() converts data in the “one row per cell” form into the data frame you get from range_read(), which involves reshaping and column typing.

df %>% spread_sheet(col_types = "D")
## is same as ...
range_read(gs4_example("deaths"), range = "E5:E7", col_types ="D")

When speed matters

If your Sheet is so large that the speed of range_read() is causing problems, consider range_speedread(). It uses a special URL that allows a Sheet to be read as comma-separated values (CSV). Access via this URL doesn’t use the Sheets API (although range_speedread() still makes an API call to retrieve Sheet metadata). As an example, on a Sheet with around 57,000 rows and 25 columns (over 1.4 million cells), range_speedread() takes ~5 seconds, whereas range_read() takes closer to 3 minutes. Why wouldn’t we always take the faster option?!? Because the speed difference is imperceptible for many Sheets and there are some downsides (described later).

range_speedread() has much the same interface as range_read().

gs4_example("gapminder") %>% 
  range_speedread(sheet = "Oceania", n_max = 3)

The output above reveals that, under the hood, range_speedread() calls an external function for CSV parsing (namely, readr::read_csv()). An important consequence is that all arguments around column type specification are passed along to the CSV-parsing function. Here is a demo using readr-style column specification:

gs4_example("deaths") %>% 
  range_speedread(
    range = "other!A5:F15",
    col_types = readr::cols(
      Age = readr::col_integer(),
      `Date of birth` = readr::col_date("%m/%d/%Y"),
      `Date of death` = readr::col_date("%m/%d/%Y")
    )
  )

Compare that to how we would read the same data with range_read():

gs4_example("deaths") %>% 
  range_read(range = "other_data", col_types = "??i?DD")

This example highlights two important differences:

  • range = "other!A5:F15" versus range = "other_data": range_speedread() can’t access a named range, whereas range_read() can.
  • readr::col_date("%m/%d/%Y") vs D: range_speedread() must parse a character representation of all cell data, including datetimes, whereas range_read() has access to the actual cell data and its type.

What’s the speed difference for something like the Africa sheet in the “gapminder” example Sheet? (around 625 rows x 6 columns, or 3700 cells)

system.time(
  gs4_example("gapminder") %>% range_speedread(sheet = "Africa")
)
system.time(
  gs4_example("gapminder") %>% range_read(sheet = "Africa")
)

The modest difference above shows that the speed difference is unlikely to be a gamechanger in many settings.

Summary of how to think about range_speedread() vs range_read():

  • Both use auth (literally, send a token), unless there was a prior to call to gs4_deauth().
  • range_speedread() is faster, but it’s not noticeable for typical Sheets.
  • range_speedread() uses readr-style column type specification, which is actually more flexible than what range_read() currently does. In future googlesheets4 releases, we will adopt readr-style column type specification.
  • range_speedread() requires more detailed column type specification, because it cannot access unformatted cell data and the actual cell type, as range_read() can.
  • range_speedread() can’t access full cell data, e.g., formatting.
  • range_speedread() can’t work with named ranges.