Understanding dropping rows(Newbie)

[Abhishek2]

HI,
I am currently working on a capstone project and I ran into an issue during the course of this.

The ride length was in negative and I wanted to get rid of the rows which had ride length in negative or above 1440.
To do that, I ran the following code :

tripdata <- tripdata[!tripdata$ride_length<0, ] ## Removing any negative ride duration
tripdata <- tripdata[!tripdata$ridelength>1440, ] ## Removing rides longer than 1 day for better scaling

On doing so, my data frame went blank.

Could you let me know where I have gone wrong?

Thank You!

Thank You!

[nirgrahamuk]

Hi!

To help us help you, could you please prepare a reproducible example (reprex) illustrating your issue? Please have a look at this guide, to see how to create one:

FAQ: How to do a minimal reproducible example ( reprex ) for beginners

A minimal reproducible example consists of the following items: A minimal dataset, necessary to reproduce the issue The minimal runnable code necessary to reproduce the issue, which can be run on the given dataset, and including the necessary information on the used packages. Let's quickly go over each one of these with examples: Minimal Dataset (Sample Data) You need to provide a data frame that is small enough to be (reasonably) pasted on a post, but big enough to reproduce your issue. Let's say, as an example, that you are working with the iris data frame head(iris) #> Sepal.Length Sepal.Width Petal.Length Petal.Width Species #> 1 5.1 3.5 1.4 0.…

[Abhishek2]

Here's the reprex:

## Packages
library(tidyverse)
library(lubridate)
#> 
#> Attaching package: 'lubridate'
#> The following objects are masked from 'package:base':
#> 
#>     date, intersect, setdiff, union
library(janitor)
#> 
#> Attaching package: 'janitor'
#> The following objects are masked from 'package:stats':
#> 
#>     chisq.test, fisher.test

## Database available at:https://divvy-tripdata.s3.amazonaws.com/index.html

trial <- tibble::tribble(
                     ~ride_id,  ~rideable_type,        ~started_at,          ~ended_at,              ~start_station_name, ~start_station_id,                ~end_station_name, ~end_station_id,  ~start_lat,   ~start_lng,    ~end_lat,     ~end_lng, ~member_casual,
           "F79335E3A77A57B5", "electric_bike", "29-03-2021 15:41", "29-03-2021 15:41", "Ashland Ave & Belle Plaine Ave",           "13249", "Ashland Ave & Belle Plaine Ave",         "13249",   41.956133,   -87.668981, 41.95614267, -87.66898483,       "member",
           "37261AB193F57280", "electric_bike", "29-03-2021 15:41", "29-03-2021 16:33", "Ashland Ave & Belle Plaine Ave",           "13249", "Ashland Ave & Belle Plaine Ave",         "13249", 41.95606717, -87.66889567,   41.956158, -87.66866283,       "member",
           "9A548550223D5776",  "classic_bike", "08-03-2021 12:12", "08-03-2021 12:44",     "Wilton Ave & Diversey Pkwy",    "TA1306000014",         "Clark St & Drummond Pl",  "TA1307000142",   41.932418,   -87.652705,   41.931248,   -87.644336,       "member",
           "5340C283D8D928D2",  "classic_bike", "26-03-2021 17:04", "26-03-2021 17:10",     "Wilton Ave & Diversey Pkwy",    "TA1306000014",         "Clark St & Drummond Pl",  "TA1307000142",   41.932418,   -87.652705,   41.931248,   -87.644336,       "member",
           "E0D5E06CBC889EE8",  "classic_bike", "18-03-2021 23:36", "18-03-2021 23:57",         "Clark St & Drummond Pl",    "TA1307000142",         "Clark St & Drummond Pl",  "TA1307000142",   41.931248,   -87.644336,   41.931248,   -87.644336,       "member"
           )

## Converting to ymd-hms

trial$started_at <- ymd_hms(trial$started_at)
trial$ended_at <- ymd_hms(trial$ended_at)

## Creating a column for ride time in minutes

trial$ridelength <- (as.double(difftime(trial$ended_at , trial$started_at)))/60 

## Removing any negative ride times

trial <- trial[!trial$ridelength<1, ]
head(trial)
#> # A tibble: 0 x 14
#> # ... with 14 variables: ride_id <chr>, rideable_type <chr>, started_at <dttm>,
#> #   ended_at <dttm>, start_station_name <chr>, start_station_id <chr>,
#> #   end_station_name <chr>, end_station_id <chr>, start_lat <dbl>,
#> #   start_lng <dbl>, end_lat <dbl>, end_lng <dbl>, member_casual <chr>,
#> #   ridelength <dbl>

[kvistj]

I see several problems here.

First is that I don't think that any of the trial$ridelength values are negative. For example, if I inspect the ridelength column before attempting to remove non-negatives, I get this:

trial$ridelength
[1] 0.0000000 0.8666667 0.5333333 0.1000000 0.3500000

As you say, you are calculating trip differences in minutes and no trial lasted longer than a minute.

Second, your data frame is blank at the end because this line:

trial <- trial[trial$ridelength > 1, ]

is trying to find all rows where trial$ridelength is greater than one and since you don't have any you get a blank data frame.