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Unpivot complex and irregular data layouts in R
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unpivotr deals with non-tabulardata, especially from spreadsheets. Use unpivotr when your source datahas any of these ‘features’:
- Multi-headered hydra
- Meaningful formatting
- Headers anywhere but at the top of each column
- Non-text headers e.g. dates
- Other stuff around the table
- Several similar tables in one sheet
- Sentinel values
- Superscript symbols
- Meaningful comments
- Nested HTML tables
If that list makes your blood boil, you’ll enjoy the function names.
behead()
deals with multi-headered hydra tables one layer of headersat a time, working from the edge of the table inwards. It’s a bit likeusingheader = TRUE
inread.csv()
, but because it’s a function,you can apply it to as many layers of headers as you need. You end upwith all the headers in columns.spatter()
is liketidyr::spread()
but preserves mixed data types.You get into a mixed-data-type situation by delaying type coercionuntilafter the table is tidy (rather than before, likeread.csv()
et al). And yes, it usually followsbehead()
.
More positive, corrective functions:
justify()
aligns column headers beforebehead()
ing, and hasdeliberate moral overtones.enhead()
attaches a header to the body of the data,a laFrankenstein. The effect is the same asbehead()
, but is morepowerful because you can choose exactly which header cells you want,paying attention to formatting (whichbehead()
doesn’t understand).isolate_sentinels()
separates meaningful symbols like"N/A"
or"confidential"
from the rest of the data, giving them some timealone think about what they’ve done.partition()
takes a sheet with several tables on it, and slashesinto pieces that each contain one table. You can then unpivot eachtable in turn withpurrr::map()
or similar.
Unpivotr uses data where each cells is represented by one row in adataframe. Like this.
Gif of tidyxl converting cells into atidy representation of one row per cellWhat can you do with tidy cells? The best places to start are:
- Spreadsheet MungingStrategies,a free, online cookbook usingtidyxl andunpivotr
- Screencasts on YouTube.
- Worked examples on GitHub.
Otherwise the basic idea is:
- Read the data with a specialist tool.
- For spreadsheets, usetidyxl.
- For plain text files, you might soon be able to usereadr, but for now you’ll have toinstall a pull-request on that package with
devtools::install_github("tidyverse/readr#760")
. - For tables in html pages, use
unpivotr::tidy_html()
- For data frames, use
unpivotr::as_cells()
– this should be alast resort, because by the time the data is in a conventionaldata frame, it is often too late – formatting has been lost, andmost data types have been coerced to strings.
- Either
behead()
straight away, elsedplyr::filter()
separatelyfor the header cells and the data cells, and then recombine withenhead()
. spatter()
so that each column has one data type.
library(unpivotr)library(tidyverse)#> ── Attaching core tidyverse packages ──────────────────────── tidyverse 2.0.0 ──#> ✔ dplyr 1.1.4 ✔ readr 2.1.5#> ✔ forcats 1.0.0 ✔ stringr 1.5.1#> ✔ ggplot2 3.5.1 ✔ tibble 3.2.1#> ✔ lubridate 1.9.3 ✔ tidyr 1.3.1#> ✔ purrr 1.0.2#> ── Conflicts ────────────────────────────────────────── tidyverse_conflicts() ──#> ✖ dplyr::filter() masks stats::filter()#> ✖ dplyr::lag() masks stats::lag()#> ✖ tidyr::pack() masks unpivotr::pack()#> ✖ tidyr::unpack() masks unpivotr::unpack()#> ℹ Use the conflicted package (<http://conflicted.r-lib.org/>) to force all conflicts to become errorsx<-purpose$`up-left left-up`x# A pivot table in a conventional data frame. Four levels of headers, in two#> X2 X3 X4 X5 X6 X7#> 1 <NA> <NA> Female <NA> Male <NA>#> 2 <NA> <NA> 0 - 6 7 - 10 0 - 6 7 - 10#> 3 Bachelor's degree 15 - 24 7000 27000 <NA> 13000#> 4 <NA> 25 - 44 12000 137000 9000 81000#> 5 <NA> 45 - 64 10000 64000 7000 66000#> 6 <NA> 65+ <NA> 18000 7000 17000#> 7 Certificate 15 - 24 29000 161000 30000 190000#> 8 <NA> 25 - 44 34000 179000 31000 219000#> 9 <NA> 45 - 64 30000 210000 23000 199000#> 10 <NA> 65+ 12000 77000 8000 107000#> 11 Diploma 15 - 24 <NA> 14000 9000 11000#> 12 <NA> 25 - 44 10000 66000 8000 47000#> 13 <NA> 45 - 64 6000 68000 5000 58000#> 14 <NA> 65+ 5000 41000 1000 34000#> 15 No Qualification 15 - 24 10000 43000 12000 37000#> 16 <NA> 25 - 44 11000 36000 21000 50000#> 17 <NA> 45 - 64 19000 91000 17000 75000#> 18 <NA> 65+ 16000 118000 9000 66000#> 19 Postgraduate qualification 15 - 24 <NA> 6000 <NA> <NA>#> 20 <NA> 25 - 44 5000 86000 7000 60000#> 21 <NA> 45 - 64 6000 55000 6000 68000#> 22 <NA> 65+ <NA> 13000 <NA> 18000# rows and two columns.y<- as_cells(x)# 'Tokenize' or 'melt' the data frame into one row per celly#> # A tibble: 132 × 4#> row col data_type chr#> <int> <int> <chr> <chr>#> 1 1 1 chr <NA>#> 2 2 1 chr <NA>#> 3 3 1 chr Bachelor's degree#> 4 4 1 chr <NA>#> 5 5 1 chr <NA>#> 6 6 1 chr <NA>#> 7 7 1 chr Certificate#> 8 8 1 chr <NA>#> 9 9 1 chr <NA>#> 10 10 1 chr <NA>#> # ℹ 122 more rowsrectify(y)# useful for reviewing the melted form as though in a spreadsheet#> # A tibble: 22 × 7#> `row/col` `1(A)` `2(B)` `3(C)` `4(D)` `5(E)` `6(F)`#> <int> <chr> <chr> <chr> <chr> <chr> <chr>#> 1 1 <NA> <NA> Female <NA> Male <NA>#> 2 2 <NA> <NA> 0 - 6 7 - 10 0 - 6 7 - 10#> 3 3 Bachelor's degree 15 - 24 7000 27000 <NA> 13000#> 4 4 <NA> 25 - 44 12000 137000 9000 81000#> 5 5 <NA> 45 - 64 10000 64000 7000 66000#> 6 6 <NA> 65+ <NA> 18000 7000 17000#> 7 7 Certificate 15 - 24 29000 161000 30000 190000#> 8 8 <NA> 25 - 44 34000 179000 31000 219000#> 9 9 <NA> 45 - 64 30000 210000 23000 199000#> 10 10 <NA> 65+ 12000 77000 8000 107000#> # ℹ 12 more rowsy %>% behead("up-left","sex") %>%# Strip headers behead("up","life-satisfication") %>%# one behead("left-up","qualification") %>%# by behead("left","age-band") %>%# one. select(-row,-col,-data_type,count=chr) %>%# cleanup mutate(count= as.integer(count))#> # A tibble: 80 × 5#> count sex `life-satisfication` qualification `age-band`#> <int> <chr> <chr> <chr> <chr>#> 1 7000 Female 0 - 6 Bachelor's degree 15 - 24#> 2 12000 Female 0 - 6 Bachelor's degree 25 - 44#> 3 10000 Female 0 - 6 Bachelor's degree 45 - 64#> 4 NA Female 0 - 6 Bachelor's degree 65+#> 5 27000 Female 7 - 10 Bachelor's degree 15 - 24#> 6 137000 Female 7 - 10 Bachelor's degree 25 - 44#> 7 64000 Female 7 - 10 Bachelor's degree 45 - 64#> 8 18000 Female 7 - 10 Bachelor's degree 65+#> 9 NA Male 0 - 6 Bachelor's degree 15 - 24#> 10 9000 Male 0 - 6 Bachelor's degree 25 - 44#> # ℹ 70 more rows
Note the compass directions in the code above, which hint tobehead()
where to find the header cell for each data cell.
"up-left"
means the header (Female
,Male
) is positioned up andto the left of the columns of data cells it describes."up"
means the header (0 - 6
,7 - 10
) is positioned directlyabove the columns of data cells it describes."left-up"
means the header (Bachelor's degree
,Certificate
,etc.) is positioned to the left and upwards of the rows of data cellsit describes."left"
means the header (15 - 24
,25 - 44
, etc.) is positioneddirectly to the left of the rows of data cells it describes.
# install.packages("devtools") # If you don't already have devtoolsdevtools::install_github("nacnudus/unpivotr",build_vignettes=TRUE)
The version 0.4.0 release had somee breaking changes. SeeNEWS.md
fordetails. The previous version can be installed as follow:
devtools::install_version("unpivotr",version="0.3.1",repos="http://cran.us.r-project.org")
unpivotr is inspired byDatabaker, acollaboration between theUnited Kingdom Office of NationalStatistics andThe Sensible CodeCompany.unpivotr.
jailbreaker attempts to extractnon-tabular data from spreadsheets into tabular structures automaticallyvia some clever algorithms.unpivotr differs by being lessmagic, and equipping you to express what you want to do.
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Unpivot complex and irregular data layouts in R