Name: R中的數據框架 - 在R中導入CSV文件 (Data frames in R - Import a CSV in R)
Uploaded: 2021-01-14T08:56:42.000Z
Duration: 3 min 24 s
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So, now we know how read.table() works, and that paves our way to learning some shortcuts.

The file we loaded into R the previous lesson is a CSV file; it is a simple text document

in which the values are separated by commas.

CSV files are extremely common, so R’s brainy developers have given us a shortcut function

This function is from the read.table() family, and it is called read.csv().

read.csv() takes fewer arguments than read.table(), because its defaults are set in a very

convenient way; headers are set to TRUE, and separators are set to a comma. All we need to do in order to read

a table is pass the name of the file, and specify whether we want our strings to be

Apart from comma-separated, values in a text data file can be separated by tabs; these

types of documents are called tab-delimited files.

And just as with CSVs, there is a read.table() shortcut to reading them: read.delim().

What’s happening behind the scenes here is that the sep = argument is set to \t, header

is again TRUE, and a bunch of other useful arguments are set to default to their most

Now, just before we wrap this up, I want to mention a few important things.

First, for those of you in Europe or anywhere else in the world where the notation for the

decimal is a comma, and therefore CSV files don’t really work for you, there is a read.csv2()

function designed to deal with this problem.

It reads CSV files with a semi-colon as a separator.

The same goes for read.delim()which also has a version 2 with the exact same purpose.

Often, data files from external sources come with additional text, either as an introduction

or a sign-off, which will only cause havoc in your data if your end up importing it.

Therefore, it is excellent that we can tell R to completely ignore the first few lines

If you want to restrict where R stops reading the data file, you can tell it to read a precise

For example, our Pokémon data is way too large, and I may only be interested in the

If I set nrow = 100, this is exactly what I will get.

Pay attention to what happened here: the heather doesn’t count towards the number of rows

The next lesson will be very short, and it will complete the data import/export circle: