Merge pull request #89 from zhezhaozz/zz-glimpse

Add `@glimpse`

NEWS.md

@@ -1,5 +1,8 @@
 # Tidier.jl updates
 
+## v0.7.3 - 2023-04-10
+- Added `@glimpse()`
+
 ## v0.7.2 - 2023-04-05
 - Moved repo to TidierOrg
 

Project.toml

@@ -1,7 +1,7 @@
 name = "Tidier"
 uuid = "f0413319-3358-4bb0-8e7c-0c83523a93bd"
 authors = ["Karandeep Singh"]
-version = "0.7.2"
+version = "0.7.3"
 
 [deps]
 Chain = "8be319e6-bccf-4806-a6f7-6fae938471bc"

README.md

@@ -79,6 +79,7 @@ To support R-style programming, Tidier.jl is implemented using macros.
 
 Tidier.jl currently supports the following top-level macros:
 
+- `@glimpse()`
 - `@select()`, `@rename()`, and `@distinct()`
 - `@mutate()` and `@transmute()` 
 - `@summarize()` and `@summarise()`

docs/examples/UserGuide/dataset_movies.jl

@@ -13,6 +13,6 @@ movies = dataset("ggplot2", "movies");
     @slice(1:5)
 end
 
-# Let's use the `describe()` function, which is re-exported from the `DataFrames.jl` package to describe the dataset.
+# Let's use `@glimpse()` to preview the dataset.
 
-describe(movies)
+@glimpse(movies)

docs/src/index.md

@@ -89,6 +89,7 @@ Tidier.jl currently supports the following top-level macros:
 
 ```@raw html
 !!! example "Top-level macros:"
+    - `@glimpse()`
     - `@select()`, `@rename()`, and `@distinct()`
     - `@mutate()` and `@transmute()` 
     - `@summarize()` and `@summarise()`

src/Tidier.jl

@@ -17,7 +17,7 @@ using Reexport
 export Tidier_set, across, desc, n, row_number, starts_with, ends_with, matches, if_else, case_when, ntile, 
       @select, @transmute, @rename, @mutate, @summarize, @summarise, @filter, @group_by, @ungroup, @slice, 
       @arrange, @distinct, @pull, @left_join, @right_join, @inner_join, @full_join, @pivot_wider, @pivot_longer, 
-      @bind_rows, @bind_cols, @clean_names, @count, @tally, @drop_na
+      @bind_rows, @bind_cols, @clean_names, @count, @tally, @drop_na, @glimpse
 
 # Package global variables
 const code = Ref{Bool}(false) # output DataFrames.jl code?
@@ -654,4 +654,28 @@ macro drop_na(df, exprs...)
   return df_expr
 end
 
+"""
+$docstring_glimpse
+"""
+macro glimpse(df, width = 80)
+  df_expr = quote
+    # DataFrame() needed to handle grouped data frames
+    println("Rows: ", nrow(DataFrame($(esc(df)))))
+    println("Columns: ", ncol(DataFrame($(esc(df)))))
+
+    if $(esc(df)) isa GroupedDataFrame
+      println("Groups: ", join(string.(groupcols($(esc(df)))), ", "), " [", length(keys($(esc(df)))), "]")
+    end
+
+    for (name, col) in pairs(eachcol(DataFrame($(esc(df)))))
+      rpad("." * string(name), 15) *
+      rpad(eltype(col), 15) *
+      join(col, ", ") |>
+      x -> first(x, $width) |> # show the first $width number of characters
+      println
+    end
+  end 
+  return df_expr
+end
+
 end

src/docstrings.jl

@@ -1829,4 +1829,44 @@ julia> @chain df @drop_na(starts_with("a"))
    2 │     2  missing 
    3 │     4        4
 ```
+"""
+
+const docstring_glimpse =
+"""
+    @glimpse(df, width = 80)
+
+Preview a DataFrame (or GroupedDataFrame).
+
+The `@glimpse` macro is used to preview a DataFrame or GroupedDataFrame. Each column is printed on a separate row, along with its data type and first few elements, with the output truncated based on the `width`.
+  
+# Arguments
+- `df`: A DataFrame or GroupedDataFrame.
+- `width`: The width of the output, measured in the number of characters. Defaults to 80.
+
+# Examples
+```jldoctest 
+julia> df = DataFrame(
+               a = 1:100, 
+               b = 1:100, 
+               c = repeat(["a"], 100)
+               );
+
+julia> @chain df @glimpse
+Rows: 100
+Columns: 3
+.a             Int64          1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
+.b             Int64          1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
+.c             String         a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a,
+
+julia> @chain df begin
+       @group_by(a)
+       @glimpse()
+       end
+Rows: 100
+Columns: 3
+Groups: a [100]
+.a             Int64          1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
+.b             Int64          1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
+.c             String         a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a,
+```
 """