# Introduction to R

This guide is a note for datacamp, introduction to R.

I usually use Python, thus in this note, I used Python to contrast R on data collection to data cleaning to data frame…

R | Python |
---|---|

Arithmetic with R Addition: + Subtraction: - Multiplication: * Division: / Exponentiation: ^ Modulo: %% |
Addition: + Subtraction: - Multiplication: * Division: / Exponentiation: pow() Modulo: % |

Variable assignmentmy_var <- 4 |
Variable assignmentmy_var = 4 |

What’s that data type?class() |
Data Typetype() |

Create a vector the combine function c() numeric_vector <- c(1, 2, 3) character_vector <- c(“a”, “b”, “c”) |
Create a vector?In python, we have List: [] |

Naming a vector names() some_vector <- c(“John Doe”, “poker player”) names(some_vector) <- c(“Name”, “Profession”) |
Naming a vector?I think we normally use another list And we use zip() function to put two lists together. Or we use dict() |

One unique feature: vectors can be added together. If a <- c(1, 2, 3), b <- c(4, 5, 6), then a + b would be c(5, 7, 9) | Lists added together would be like stick together, instead of adding each element one by one. For example, a = [1, 2, 3], b = [4, 5, 6], a + b would be [1, 2, 3, 4, 5, 6] |

Some functions sum() max() min() mean(na.rm = FALSE) # na.rm: drop NA data abs() round() |
Some functionssum() max() min() np.mean() |

Index of vectors In R, we start from 1. First element, vector_sample[1]. First to third element, vector_sample[c(1,2,3)] or vector_sample[1:3] |
Index of vectors In python, we start from 0. |

What’s a matrix? matrix(1:9, byrow = TRUE, nrow = 3) using `byrow` , we would fill the matrix by rows! |
Python doesn’t have this function. We use pandas.DataFrame or numpy to make a matrix, and we can use numpy.reshape. |