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skim() is an alternative to summary(), quickly providing a broad overview of a data frame. It handles data of all types, dispatching a different set of summary functions based on the types of columns in the data frame.

Usage

skim(data, ..., .data_name = NULL)

skim_tee(data, ..., skim_fun = skim)

skim_without_charts(data, ..., .data_name = NULL)

Arguments

data

A tibble, or an object that can be coerced into a tibble.

...

Columns to select for skimming. When none are provided, the default is to skim all columns.

.data_name

The name to use for the data. Defaults to the same as data.

skim_fun

The skim function used.

skim

The skimming function to use in skim_tee().

Value

A skim_df object, which also inherits the class(es) of the input data. In many ways, the object behaves like a tibble::tibble().

Details

Each call produces a skim_df, which is a fundamentally a tibble with a special print method. One unusual feature of this data frame is pseudo- namespace for columns. skim() computes statistics by data type, and it stores them in the data frame as <type>.<statistic>. These types are stripped when printing the results. The "base" skimmers (n_missing and complete_rate) are the only columns that don't follow this behavior. See skim_with() for more details on customizing skim() and get_default_skimmers() for a list of default functions.

If you just want to see the printed output, call skim_tee() instead. This function returns the original data. skim_tee() uses the default skim(), but you can replace it with the skim argument.

The data frame produced by skim is wide and sparse. To avoid type coercion skimr uses a type namespace for all summary statistics. Columns for numeric summary statistics all begin numeric; for factor summary statistics begin factor; and so on.

See partition() and yank() for methods for transforming this wide data frame. The first function splits it into a list, with each entry corresponding to a data type. The latter pulls a single subtable for a particular type from the skim_df.

skim() is designed to operate in pipes and to generally play nicely with other tidyverse functions. This means that you can use tidyselect helpers within skim to select or drop specific columns for summary. You can also further work with a skim_df using dplyr functions in a pipeline.

Customizing skim

skim() is an intentionally simple function, with minimal arguments like summary(). Nonetheless, this package provides two broad approaches to how you can customize skim()'s behavior. You can customize the functions that are called to produce summary statistics with skim_with().

Unicode rendering

If the rendered examples show unencoded values such as <U+2587> you will need to change your locale to allow proper rendering. Please review the Using Skimr vignette for more information (vignette("Using_skimr", package = "skimr")).

Otherwise, we export skim_without_charts() to produce summaries without the spark graphs. These are the source of the unicode dependency.

Examples

skim(iris)
#> ── Data Summary ────────────────────────
#>                            Values
#> Name                       iris  
#> Number of rows             150   
#> Number of columns          5     
#> _______________________          
#> Column type frequency:           
#>   factor                   1     
#>   numeric                  4     
#> ________________________         
#> Group variables            None  
#> 
#> ── Variable type: factor ───────────────────────────────────────────────────────
#>   skim_variable n_missing complete_rate ordered n_unique
#> 1 Species               0             1 FALSE          3
#>   top_counts               
#> 1 set: 50, ver: 50, vir: 50
#> 
#> ── Variable type: numeric ──────────────────────────────────────────────────────
#>   skim_variable n_missing complete_rate mean    sd  p0 p25  p50 p75 p100 hist 
#> 1 Sepal.Length          0             1 5.84 0.828 4.3 5.1 5.8  6.4  7.9 ▆▇▇▅▂
#> 2 Sepal.Width           0             1 3.06 0.436 2   2.8 3    3.3  4.4 ▁▆▇▂▁
#> 3 Petal.Length          0             1 3.76 1.77  1   1.6 4.35 5.1  6.9 ▇▁▆▇▂
#> 4 Petal.Width           0             1 1.20 0.762 0.1 0.3 1.3  1.8  2.5 ▇▁▇▅▃

# Use tidyselect
skim(iris, Species)
#> ── Data Summary ────────────────────────
#>                            Values
#> Name                       iris  
#> Number of rows             150   
#> Number of columns          5     
#> _______________________          
#> Column type frequency:           
#>   factor                   1     
#> ________________________         
#> Group variables            None  
#> 
#> ── Variable type: factor ───────────────────────────────────────────────────────
#>   skim_variable n_missing complete_rate ordered n_unique
#> 1 Species               0             1 FALSE          3
#>   top_counts               
#> 1 set: 50, ver: 50, vir: 50
skim(iris, starts_with("Sepal"))
#> ── Data Summary ────────────────────────
#>                            Values
#> Name                       iris  
#> Number of rows             150   
#> Number of columns          5     
#> _______________________          
#> Column type frequency:           
#>   numeric                  2     
#> ________________________         
#> Group variables            None  
#> 
#> ── Variable type: numeric ──────────────────────────────────────────────────────
#>   skim_variable n_missing complete_rate mean    sd  p0 p25 p50 p75 p100 hist 
#> 1 Sepal.Length          0             1 5.84 0.828 4.3 5.1 5.8 6.4  7.9 ▆▇▇▅▂
#> 2 Sepal.Width           0             1 3.06 0.436 2   2.8 3   3.3  4.4 ▁▆▇▂▁
skim(iris, where(is.numeric))
#> ── Data Summary ────────────────────────
#>                            Values
#> Name                       iris  
#> Number of rows             150   
#> Number of columns          5     
#> _______________________          
#> Column type frequency:           
#>   numeric                  4     
#> ________________________         
#> Group variables            None  
#> 
#> ── Variable type: numeric ──────────────────────────────────────────────────────
#>   skim_variable n_missing complete_rate mean    sd  p0 p25  p50 p75 p100 hist 
#> 1 Sepal.Length          0             1 5.84 0.828 4.3 5.1 5.8  6.4  7.9 ▆▇▇▅▂
#> 2 Sepal.Width           0             1 3.06 0.436 2   2.8 3    3.3  4.4 ▁▆▇▂▁
#> 3 Petal.Length          0             1 3.76 1.77  1   1.6 4.35 5.1  6.9 ▇▁▆▇▂
#> 4 Petal.Width           0             1 1.20 0.762 0.1 0.3 1.3  1.8  2.5 ▇▁▇▅▃

# Skim also works groupwise
iris %>%
  dplyr::group_by(Species) %>%
  skim()
#> ── Data Summary ────────────────────────
#>                            Values    
#> Name                       Piped data
#> Number of rows             150       
#> Number of columns          5         
#> _______________________              
#> Column type frequency:               
#>   numeric                  4         
#> ________________________             
#> Group variables            Species   
#> 
#> ── Variable type: numeric ──────────────────────────────────────────────────────
#>    skim_variable Species    n_missing complete_rate  mean    sd  p0  p25  p50
#>  1 Sepal.Length  setosa             0             1 5.01  0.352 4.3 4.8  5   
#>  2 Sepal.Length  versicolor         0             1 5.94  0.516 4.9 5.6  5.9 
#>  3 Sepal.Length  virginica          0             1 6.59  0.636 4.9 6.22 6.5 
#>  4 Sepal.Width   setosa             0             1 3.43  0.379 2.3 3.2  3.4 
#>  5 Sepal.Width   versicolor         0             1 2.77  0.314 2   2.52 2.8 
#>  6 Sepal.Width   virginica          0             1 2.97  0.322 2.2 2.8  3   
#>  7 Petal.Length  setosa             0             1 1.46  0.174 1   1.4  1.5 
#>  8 Petal.Length  versicolor         0             1 4.26  0.470 3   4    4.35
#>  9 Petal.Length  virginica          0             1 5.55  0.552 4.5 5.1  5.55
#> 10 Petal.Width   setosa             0             1 0.246 0.105 0.1 0.2  0.2 
#> 11 Petal.Width   versicolor         0             1 1.33  0.198 1   1.2  1.3 
#> 12 Petal.Width   virginica          0             1 2.03  0.275 1.4 1.8  2   
#>     p75 p100 hist 
#>  1 5.2   5.8 ▃▃▇▅▁
#>  2 6.3   7   ▂▇▆▃▃
#>  3 6.9   7.9 ▁▃▇▃▂
#>  4 3.68  4.4 ▁▃▇▅▂
#>  5 3     3.4 ▁▅▆▇▂
#>  6 3.18  3.8 ▂▆▇▅▁
#>  7 1.58  1.9 ▁▃▇▃▁
#>  8 4.6   5.1 ▂▂▇▇▆
#>  9 5.88  6.9 ▃▇▇▃▂
#> 10 0.3   0.6 ▇▂▂▁▁
#> 11 1.5   1.8 ▅▇▃▆▁
#> 12 2.3   2.5 ▂▇▆▅▇

# Which five numeric columns have the greatest mean value?
# Look in the `numeric.mean` column.
iris %>%
  skim() %>%
  dplyr::select(numeric.mean) %>%
  dplyr::top_n(5)
#> Selecting by numeric.mean
#> # A tibble: 4 × 1
#>   numeric.mean
#>          <dbl>
#> 1         5.84
#> 2         3.06
#> 3         3.76
#> 4         1.20

# Which of my columns have missing values? Use the base skimmer n_missing.
iris %>%
  skim() %>%
  dplyr::filter(n_missing > 0)
#> # A tibble: 0 × 15
#> # … with 15 variables: skim_type <chr>, skim_variable <chr>, n_missing <int>,
#> #   complete_rate <dbl>, factor.ordered <lgl>, factor.n_unique <int>,
#> #   factor.top_counts <chr>, numeric.mean <dbl>, numeric.sd <dbl>,
#> #   numeric.p0 <dbl>, numeric.p25 <dbl>, numeric.p50 <dbl>, numeric.p75 <dbl>,
#> #   numeric.p100 <dbl>, numeric.hist <chr>

# Use skim_tee to view the skim results and
# continue using the original data.
chickwts %>%
  skim_tee() %>%
  dplyr::filter(feed == "sunflower")
#> ── Data Summary ────────────────────────
#>                            Values
#> Name                       data  
#> Number of rows             71    
#> Number of columns          2     
#> _______________________          
#> Column type frequency:           
#>   factor                   1     
#>   numeric                  1     
#> ________________________         
#> Group variables            None  
#> 
#> ── Variable type: factor ───────────────────────────────────────────────────────
#>   skim_variable n_missing complete_rate ordered n_unique
#> 1 feed                  0             1 FALSE          6
#>   top_counts                        
#> 1 soy: 14, cas: 12, lin: 12, sun: 12
#> 
#> ── Variable type: numeric ──────────────────────────────────────────────────────
#>   skim_variable n_missing complete_rate mean   sd  p0  p25 p50  p75 p100 hist 
#> 1 weight                0             1 261. 78.1 108 204. 258 324.  423 ▆▆▇▇▃
#>    weight      feed
#> 1     423 sunflower
#> 2     340 sunflower
#> 3     392 sunflower
#> 4     339 sunflower
#> 5     341 sunflower
#> 6     226 sunflower
#> 7     320 sunflower
#> 8     295 sunflower
#> 9     334 sunflower
#> 10    322 sunflower
#> 11    297 sunflower
#> 12    318 sunflower

# Produce a summary without spark graphs
iris %>%
  skim_without_charts()
#> ── Data Summary ────────────────────────
#>                            Values    
#> Name                       Piped data
#> Number of rows             150       
#> Number of columns          5         
#> _______________________              
#> Column type frequency:               
#>   factor                   1         
#>   numeric                  4         
#> ________________________             
#> Group variables            None      
#> 
#> ── Variable type: factor ───────────────────────────────────────────────────────
#>   skim_variable n_missing complete_rate ordered n_unique
#> 1 Species               0             1 FALSE          3
#>   top_counts               
#> 1 set: 50, ver: 50, vir: 50
#> 
#> ── Variable type: numeric ──────────────────────────────────────────────────────
#>   skim_variable n_missing complete_rate mean    sd  p0 p25  p50 p75 p100
#> 1 Sepal.Length          0             1 5.84 0.828 4.3 5.1 5.8  6.4  7.9
#> 2 Sepal.Width           0             1 3.06 0.436 2   2.8 3    3.3  4.4
#> 3 Petal.Length          0             1 3.76 1.77  1   1.6 4.35 5.1  6.9
#> 4 Petal.Width           0             1 1.20 0.762 0.1 0.3 1.3  1.8  2.5