Plot a legend outside of the plotting area in base graphics

Question

I've only recently started using RStudio to learn R, so I may have some fundamental questions. Regarding the "sample" function, one of them. My dataset contains 402224 observations across 147 different variables, to be more precise. My job is to create a dataframe from a sample of 50 observations, then go on. However, y = sample(mydata, 50, replace = TRUE, prob = NULL) results in a dataset with 40224 observations over 50 variables when the function sample is called. That is, variables rather than objectives are sampled.

Have you thought about why it occurs? I want to say thank you.

Answer 1

It appears that you are experiencing some confusion with the sample function in R. The sample function is primarily used to randomly sample elements from a vector, not to sample rows or observations from a data frame. When you apply sample to a data frame directly, it behaves differently from what you expect.

To randomly sample rows (observations) from your data frame mydata, you should use row indices to sample rows and create a new data frame. Here's how you can do it:

# Assuming 'mydata' is your data frame # Sample 50 rows from 'mydata' without replacement sampled_data <- mydata[sample(nrow(mydata), 50, replace = FALSE), ]

Here's what each part of this code does:

1. nrow(mydata) calculates the number of rows in your data frame mydata. This will be the population from which you want to sample.

2. sample(nrow(mydata), 50, replace = FALSE) generates 50 random row indices from 1 to the number of rows in your data frame without replacement. This means that each row will be selected only once.

3. mydata[sampled_indices, ] subsets your data frame to include only the rows corresponding to the sampled indices, creating a new data frame called sampled_data.

Sampled_data will contain 50 randomly selected rows from your original data frame mydata.

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