--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/.hgignore	Thu Sep 14 21:00:05 2017 +0100
@@ -0,0 +1,1 @@
+2-Io/matrix.txt
\ No newline at end of file

--- a/2-Io/day2-self-study.io	Thu Sep 14 20:24:25 2017 +0100
+++ b/2-Io/day2-self-study.io	Thu Sep 14 21:00:05 2017 +0100
@@ -127,6 +127,72 @@
 my_arr get(5, 5) println
 
 
+#6) Bonus "transpose" method (ugly and inefficient method)
+TwoDList transpose := method(
+    new_list := TwoDList clone
+    x := self arr size
+    y := self arr at(0) size
+    new_list dim(y, x)
+    for (i, 0, x - 1,
+        for (j, 0, y - 1,
+            new_list set(j, i, self get(i, j))
+        )
+    )
+    return new_list
+)
+
+transposed := my_arr transpose
+transposed get(1, 2) println
+transposed get(0, 1) println
+transposed get(2, 1) println
+transposed get(1, 0) println
+
+#7) Write a matrix to a file and read it back
+# Might as well use the TwoDList as a matrix
+# Note: This isn't white-space safe, but nvm
+TwoDList as_string := method(
+    x := self arr size
+    y := self arr at(0) size
+    #str := "#{self arr size}×#{self arr at(0) size}\n" interpolate
+    str := ""
+    for (i, 0, x - 1,
+        for (j, 0, y - 1,
+            str = "#{str}#{self get(i, j)} " interpolate
+        )
+        str = "#{str asMutable strip}\n" interpolate
+    )
+)
+
+TwoDList load := method(matrix_string,
+    # strip to make sure that we don't get trailing new lines
+    rows := matrix_string strip split("\n")
+    row_count := rows size
+    # Ugly way to get column count
+    col_count := rows at(0) split(" ") size
+    self dim(row_count, col_count)    
+    for (i, 0, row_count - 1,
+        row := rows at(i) split(" ")
+        for (j, 0, col_count - 1,
+            self set(i, j, row at(j))
+        )
+    )
+)
+matrix_file := "matrix.txt"
+f := File with(matrix_file)
+f remove
+f openForUpdating
+f write(my_arr as_string)
+f flush
+f close
+
+f2 := File with(matrix_file)
+f2 openForReading
+new_list := TwoDList clone
+new_list load(f2 contents)
+f2 close
+new_list get(1, 2) println
+new_list get(0, 1) println
+
 
 # 4) final piece
 list(1, 2, 3, "foo") myAverage
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