update layout of all exercises
This commit is contained in:
Bogumił Kamiński
@@ -11,16 +11,47 @@
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Interpolate the expression `1 + 2` into a string `"I have apples worth 3USD"`
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(replace `3` by a proper interpolation expression) and replace `USD` by `$`.
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<details>
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<summary>Solution</summary>
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```
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julia> "I have apples worth $(1+2)\$"
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"I have apples worth 3\$"
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```
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</details>
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### Exercise 2
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Download the file `https://archive.ics.uci.edu/ml/machine-learning-databases/iris/iris.data`
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as `iris.csv` to your local folder.
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<details>
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<summary>Solution</summary>
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```
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import Downloads
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Downloads.download("https://archive.ics.uci.edu/ml/machine-learning-databases/iris/iris.data",
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"iris.csv")
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```
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</details>
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### Exercise 3
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Write the string `"https://archive.ics.uci.edu/ml/machine-learning-databases/iris/iris.data"`
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in two lines so that it takes less horizontal space.
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<details>
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<summary>Solution</summary>
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```
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"https://archive.ics.uci.edu/ml/\
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machine-learning-databases/iris/iris.data"
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```
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</details>
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### Exercise 4
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Load data stored in `iris.csv` file into a `data` vector where each element
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@@ -28,73 +59,9 @@ should be a named tuple of the form `(sl=1.0, sw=2.0, pl=3.0, pw=4.0, c="x")` if
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the source line had data `1.0,2.0,3.0,4.0,x` (note that first four elements are parsed
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as floats).
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### Exercise 5
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The `data` structure is a vector of named tuples, change it to a named tuple
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of vectors (with the same field names) and call it `data2`.
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### Exercise 6
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Calculate the frequency of each type of Iris type (`c` field in `data2`).
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### Exercise 7
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Create a vector `c2` that is derived from `c` in `data2` but holds inline strings,
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vector `c3` that is a `PooledVector`, and vector `c4` that holds `Symbol`s.
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Compare sizes of the three objects.
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### Exercise 8
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You know that `refs` field of `PooledArray` stores an integer index of a given
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value in it. Using this information make a scatter plot of `pl` vs `pw` vectors
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in `data2`, but for each Iris type give a different point color (check the
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`color` keyword argument meaning in the Plots.jl manual; you can use the
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`plot_color` function).
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### Exercise 9
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Type the following string `"a²=b² ⟺ a=b ∨ a=-b"` in your terminal and bind it to
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`str` variable (do not copy paste the string, but type it).
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### Exercise 10
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In the `str` string from exercise 9 find all matches of a pattern where `a`
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is followed by `b` but there can be some characters between them.
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# Solutions
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<details>
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<summary>Solution</summary>
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<summary>Show!</summary>
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### Exercise 1
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Solution:
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```
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julia> "I have apples worth $(1+2)\$"
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"I have apples worth 3\$"
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```
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### Exercise 2
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Solution:
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```
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import Downloads
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Downloads.download("https://archive.ics.uci.edu/ml/machine-learning-databases/iris/iris.data",
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"iris.csv")
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```
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### Exercise 3
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Solution:
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```
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"https://archive.ics.uci.edu/ml/\
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machine-learning-databases/iris/iris.data"
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```
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### Exercise 4
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Solution:
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```
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julia> function line_parser(line)
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elements = split(line, ",")
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@@ -125,8 +92,16 @@ Note that we used `1:end-1` selector to drop last element from the read lines
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since it is empty. This is the reason why adding the
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`@assert length(elements) == 5` check in the `line_parser` function is useful.
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</details>
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### Exercise 5
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The `data` structure is a vector of named tuples, change it to a named tuple
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of vectors (with the same field names) and call it `data2`.
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<details>
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<summary>Solution</summary>
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Later in the book you will learn more advanced ways to do it. Here let us
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use a most basic approach:
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@@ -138,9 +113,15 @@ data2 = (sl=[d.sl for d in data],
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c=[d.c for d in data])
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```
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</details>
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### Exercise 6
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Solution:
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Calculate the frequency of each type of Iris type (`c` field in `data2`).
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<details>
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<summary>Solution</summary>
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```
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julia> using FreqTables
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@@ -153,9 +134,17 @@ Dim1 │
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"Iris-virginica" │ 50
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```
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</details>
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### Exercise 7
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Solution:
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Create a vector `c2` that is derived from `c` in `data2` but holds inline strings,
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vector `c3` that is a `PooledVector`, and vector `c4` that holds `Symbol`s.
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Compare sizes of the three objects.
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<details>
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<summary>Solution</summary>
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```
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julia> using InlineStrings
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@@ -213,16 +202,34 @@ julia> Base.summarysize(c4)
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1240
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```
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</details>
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### Exercise 8
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Solution:
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You know that `refs` field of `PooledArray` stores an integer index of a given
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value in it. Using this information make a scatter plot of `pl` vs `pw` vectors
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in `data2`, but for each Iris type give a different point color (check the
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`color` keyword argument meaning in the Plots.jl manual; you can use the
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`plot_color` function).
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<details>
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<summary>Solution</summary>
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```
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using Plots
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scatter(data2.pl, data2.pw, color=plot_color(c3.refs), legend=false)
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```
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</details>
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### Exercise 9
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Type the following string `"a²=b² ⟺ a=b ∨ a=-b"` in your terminal and bind it to
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`str` variable (do not copy paste the string, but type it).
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<details>
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<summary>Solution</summary>
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The hard part is typing `²`, `⟺` and `∨`. You can check how to do it using help:
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```
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help?> ²
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@@ -237,8 +244,16 @@ help?> ∨
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Save the string in the `str` variable as we will use it in the next exercise.
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</details>
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### Exercise 10
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In the `str` string from exercise 9 find all matches of a pattern where `a`
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is followed by `b` but there can be some characters between them.
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<details>
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<summary>Show!</summary>
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The exercise does not specify how the matching should be done. If we
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want it to be eager (match as much as possible), we write:
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