init research

dataframe/plugins/kotlin-dataframe/testData/box/groupBy_count.kt

@@ -0,0 +1,16 @@
+import org.jetbrains.kotlinx.dataframe.*
+import org.jetbrains.kotlinx.dataframe.annotations.*
+import org.jetbrains.kotlinx.dataframe.api.*
+import org.jetbrains.kotlinx.dataframe.io.*
+
+fun box(): String {
+    val df = dataFrameOf("a")(1, 1, 2, 3, 3).groupBy { a }.count()
+    val i: Int = df.count[0]
+
+    val df1 = dataFrameOf("a")(1, 1, 2, 3, 3).groupBy { a }.count { a > 1 }
+    val i1: Int = df1.count[0]
+
+    val df2 = dataFrameOf("a")(1, 1, 2, 3, 3).groupBy { a }.count("myCol") { a > 1 }
+    val i2: Int = df2.myCol[0]
+    return "OK"
+}