Notes.Rmd

---
title: "Course Notes"
output: 
  html_document:
    toc: true
    toc_float: true
    collapsed: false
    number_sections: false
    toc_depth: 2
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(message=FALSE,warning=FALSE, cache=TRUE)
```

# Notes (for mac)

1. **Insert R code in HTML**: 
```{r eval=FALSE}
Option+Command+i  
```
2. **Run inserted R code:** 
```{r eval=FALSE}
Control+Enter  
```
3. **Insert R code without running it:**
```{r eval=FALSE}
{r eval=false}
```
4. **Insert linked text:** 
```{r eval=FALSE}
[text](link)
```
5. **Change color of text:** 
```{r eval=FALSE}
<span style="color:red">TEXT HERE</span>
```
  
  
# Class Notes

## Notes from 1/4/19
```{r eval=FALSE}

# Class Type Examples
a <- 1
b <- "hello world"
d <- "3"
vector <- c(1,2,3,4,5,6,7,6,5,6,5,1000)
class(a)
class(b)
class(vector)

# Indexing
vector[8]
vector[8:10]
vector[c(10,10,10,10,10,10)]
vector[c(1,2,3,3,2,1)]

# Logical Indexing
vector[vector > 6]
vector[vector < 6]
vector[vector >= 6]
vector[vector <= 6]
vector[vector == 6]
vector[vector != 6]  

# Replcament Usiong Indexing
vector[8] <- 3000
vector[1:2] <- c(10,15)
vector[1:2] <- c(10,15,17)  # Error: cannot replace 2 positions with 3 items
vector[7] <- "j"  # Turns entire vector into character class

# Class Types
a <- c("1","2","3")
class(a)
b <- a
class(b)
as.numeric(b)

# Splitting by period
a <- "gwaesr. dfgh fgiu out. yirde tsdgf."
a[1]
b <- strsplit(a,split="[.]")
class(b)\

# Lists
a <- "gwaesdfghfgiouigrdtsdgf."
a[1]
b <- strsplit(a,split="")
class(b)
b
b[[1]]
b[[1]][5]
example_list <- list(a=1, b=4, d=c(1,2,3,4))
example_list[[2]]

#Unlisting
b <- unlist(strsplit(a,split=""))
b[5]

# Matrices
a <- matrix(0, nrow = 5, ncol = 5)
View(a)

# Data Frames
first_names <- c("jeff", "matt", "steve")
ages <- c(100, 200, 150)
grades <- c(89, 56, 99)
everybody <- data.frame(first_names, ages, grades)
View(everybody)
everybody$first_names
everybody$ages[1] <- 12
everybody$grades[1]

# Levels
class(everybody$first_names) # Factor Class
```

## Class Notes 2/15/19
```{r}
a <- data.frame()
Names <- c("Peter","Paul","Mary")
Ages <- c(1000,1200,100)
Sex <- c("M","M","F")
my_df <- data.frame(Names,Ages,Sex)
```

Add NA in order to add empty data cells.  
```{r}
a <- data.frame()
Names <- c("Peter","Paul","Mary",NA)
Ages <- c(1000,1200,100,50)
Sex <- c("M","M","F",NA)
my_df <- data.frame(Names,Ages,Sex)
```

Prevent strings from being treated as factors.  
```{r}
a <- data.frame()
Names <- c("Peter","Paul","Mary",NA)
Ages <- c(1000,1200,100,50)
Sex <- c("M","M","F",NA)
my_df <- data.frame(Names,Ages,Sex)
my_df$Names <- as.character(my_df$Names)
my_df$Names
```

```{r}
# Create dataframe
a <- c(1,2,3,2,3,4,5,4)
b <- c(4,3,4,3,2,1,2,3)
plot_df <- data.frame(a,b)


# basic scatterplot
library(ggplot2)
ggplot(plot_df, aes(x=a,y=b))+
  geom_point()
```

```{r}
a <- c(1,2,3,2,3,4,5,4)
b <- c(4,3,4,3,2,1,2,3)
plot_df <- data.frame(a,b)

# customize, add regression line
library(ggplot2)
ggplot(plot_df, aes(x=a,y=b))+
  geom_point(size=2)+
  geom_smooth(method=lm)+
  coord_cartesian(xlim=c(0,7),ylim=c(0,10))+
  xlab("x-axis label")+
  ylab("y-axis label")+
  ggtitle("I made a scatterplot")+
  theme_classic(base_size=12)+
  theme(plot.title = element_text(hjust = 0.5))
```

```{r}
factor_one <- rep(as.factor(c("A","B","C")),2)
factor_two <- rep(as.factor(c("IIA","IIB")),3)
dv_means <- c(20,30,40,20,40,40)
dv_SEs   <- c(4,3.4,4,3,2,4)
plot_df <- data.frame(factor_one,
                      factor_two,
                      dv_means,
                      dv_SEs)

library(ggplot2)
ggplot(plot_df, aes(x=factor_one,y=dv_means,
                    group=factor_two,
                    color=factor_two,
                    fill=factor_two))+
  geom_bar(stat="identity", position="dodge")+
  geom_errorbar(aes(ymin=dv_means-dv_SEs,
                    ymax=dv_means+dv_SEs),
                position=position_dodge(width=0.9),
                width=.2,
                color="black")+
  coord_cartesian(ylim=c(0,100))+
  xlab("x-axis label")+
  ylab("y-axis label")+
  ggtitle("Bar graph 2 factors")+
  theme_classic(base_size=12)+
  theme(plot.title = element_text(hjust = 0.5))
```