CODEWITHSUNDEEP
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CA Burns
CA Burns

Reputation: 111

How to count the number of rows that meets a specific criteria in R programming?

In this data frame, I'm trying to find the number of right handed batters in the <5 years group without simply counting it manually. Here's a sample of the data:

Status Handed <5 yrs Right <5 yrs Right <5 yrs Left

How to I use an R function to do that instead of counting it out?

Upvotes: 0

Views: 56

Answers (3)

Varun kadekar
Varun kadekar

Reputation: 427

**length(df[df$Status=='<5 yrs' & df$Handed == 'Right',])**

here df is name of the data frame you are using. This works

Or use sqldf package. 

**install.packages("sqldf")
**library("sqldf")**
**df$Count=1**
**sqldf("select sum(Count) from df where Status='<5 yrs' and 
  Handed='Right')****

Upvotes: 0

Gregor Thomas
Gregor Thomas

Reputation: 145755

The standard solution to count something is sum. In this case, 

sum(df$Handed[df$Status == "<5 yrs"] == "Right")

For counting the number of times a condition occurs, sum should be your go-to.

table, as demo'd in Yannis's answer is useful if you want counts of all possibilities, e.g., table(df$Handed[df$Status == "<5 yrs"]) gives the counts of Left and Right (and anything else in the handed column, and it is also do crosstabulations, e.g., with(df, table(Handed, Status)) will give counts of handedness for each of the status categories.

Upvotes: 0

Yannis Vassiliadis
Yannis Vassiliadis

Reputation: 1709

You could try:

table(df$Handed[df$Status == "<5 yrs"])

Or if you want the full breakdown based on Status category, you just do:

table(df$Handed, df$Status)

Upvotes: 1

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