From 58d5dad0321d33b1135045f9a51b1a70d70eb936 Mon Sep 17 00:00:00 2001
From: Wei Wei <weiwei@WeitekiMacBook-Air.local>
Date: Thu, 22 Sep 2016 12:39:23 -0400
Subject: [PATCH] I finished lessons of probablities.

---
 .gitignore            |  4 ++++
 Class 4 - Swirl.Rproj | 13 +++++++++++++
 cards.R               | 23 +++++++++++++++++++++++
 lesson1.csv           | 28 ++++++++++++++++++++++++++++
 4 files changed, 68 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Class 4 - Swirl.Rproj
 create mode 100644 cards.R
 create mode 100644 lesson1.csv

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..5b6a065
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+.Rproj.user
+.Rhistory
+.RData
+.Ruserdata
diff --git a/Class 4 - Swirl.Rproj b/Class 4 - Swirl.Rproj
new file mode 100644
index 0000000..8e3c2eb
--- /dev/null
+++ b/Class 4 - Swirl.Rproj	
@@ -0,0 +1,13 @@
+Version: 1.0
+
+RestoreWorkspace: Default
+SaveWorkspace: Default
+AlwaysSaveHistory: Default
+
+EnableCodeIndexing: Yes
+UseSpacesForTab: Yes
+NumSpacesForTab: 2
+Encoding: UTF-8
+
+RnwWeave: Sweave
+LaTeX: pdfLaTeX
diff --git a/cards.R b/cards.R
new file mode 100644
index 0000000..a1a773b
--- /dev/null
+++ b/cards.R
@@ -0,0 +1,23 @@
+values <- c("A", as.character(2:10), "J", "Q", "K")
+suits <- c("spades", "hearts", "diamonds", "clubs")
+
+# Create a deck as a 13x4 matrix which is easy to verify by eye.
+deck <- sapply(suits, function(suit)paste(values, suit, sep=":"))
+# Verify.
+deck
+# Note the value of a card is its row index (if Aces are low.)
+
+# Select n cards from a deck at random without replacement.
+hand <- function(n, deck)sample(deck, n, replace=FALSE)
+
+# Deal k hands of n cards each as a kxn matrix.
+deal <- function(k, n, deck){
+  # Select kxn cards at random without replacement.
+  temp <- hand(k*n, deck)
+  # Reshape selections into a kxn matrix. Since R
+  # fills by column, this is like dealing the cards
+  # out in circular order around the table. (Not that
+  # it makes any difference since the selection process
+  # is a random permutation of the deck anyway.)
+  matrix(temp, k, n)
+}
\ No newline at end of file
diff --git a/lesson1.csv b/lesson1.csv
new file mode 100644
index 0000000..7668670
--- /dev/null
+++ b/lesson1.csv
@@ -0,0 +1,28 @@
+"time","answer","id"
+1474557960867,"install.packages(swirl)","YOUR NAME"
+1474558061782,"library(swirl)","YOUR NAME"
+1474558106237,"swirl()","YOUR NAME"
+1474559387829,"11/12","YOUR NAME"
+1474559439020,"deck","YOUR NAME"
+1474559450620,"52","YOUR NAME"
+1474559464553,"4/52","YOUR NAME"
+1474559484601,"0","YOUR NAME"
+1474559512863,"12/52","YOUR NAME"
+1474559599848,"5/25","YOUR NAME"
+1474559683724,"2/52","YOUR NAME"
+1474559702359,"2/51","YOUR NAME"
+1474559844628,"H <-read.table(~/.rstudio-desktop/history_database, sep=:, fill=T, stringsAsFactors=F)","YOUR NAME"
+1474559844672,"names(H) <- c(time, answer)","YOUR NAME"
+1474559844679,"H$id <- YOUR NAME","YOUR NAME"
+1474559844690,"write.csv(H, file = lesson1.csv, row.names = FALSE)","YOUR NAME"
+1474559858493,"swirl()","YOUR NAME"
+1474559988869,"H <-read.table(~/.rstudio-desktop/history_database, sep=:, fill=T, stringsAsFactors=F)","YOUR NAME"
+1474559988903,"names(H) <- c(time, answer)","YOUR NAME"
+1474559988924,"H$id <- YOUR NAME","YOUR NAME"
+1474559988939,"write.csv(H, file = lesson1.csv, row.names = FALSE)","YOUR NAME"
+1474560044995,"swirl()","YOUR NAME"
+1474560722478,"1.28","YOUR NAME"
+1474560741861,"0.64","YOUR NAME"
+1474560770116,"0.64","YOUR NAME"
+1474560967720,"bye()","YOUR NAME"
+1474561079682,"H <-read.table(~/.rstudio-desktop/history_database, sep=:, fill=T, stringsAsFactors=F)","YOUR NAME"