Using Str_Detect in a for loop

Question

I'm working on a dataset that has a product description column and we are trying to extract info out of that dataset and create a new column based on the results. For instance if 'Room Darkening' is within the product description, then create a new column with the value of 'RD' for that row.

Here is the code I have:

for (i in 1:length(HD$Fabric.Description)){
  if (str_detect(HD$Fabric.Description[i],'RD')){
    HD$Type[i] == "RD"
  } 
  if (str_detect(HD$Fabric.Description[i],'Room Darkening')){
    HD$Type[i] == "RD"
  } 
  if (str_detect(HD$Fabric.Description[i],'LF')){
    HD$Type[i] == "LF"
  } 
  if (str_detect(HD$Fabric.Description[i],'Light Filtering')){
    HD$Type[i] == "LF"
  } else {
    HD$Type[i] == 'Other'
  }
}

The code runs without error but when I look at the HD dataset, the column doesn't appear.

head(HD)
X         Date Month Week Printer      FabricColor Fabric                    Product
1 1  1/8/19 0:00     1    2    5202 A1-321BOTTOMRAIL     A1 Silhouette Window Shadings
2 2 3/22/19 0:00     3   12    5201           A1-110     A1 Silhouette Window Shadings
3 3  4/3/19 0:00     4   14    5204        A1-266FCH     A1 Silhouette Window Shadings
4 4 4/18/19 0:00     4   16    5204        A1-168-BR     A1 Silhouette Window Shadings
5 5 1/11/19 0:00     1    2    5204         A1-107BR     A1 Silhouette Window Shadings
6 6 1/18/19 0:00     1    3    5204        A1-627FCH     A1 Silhouette Window Shadings
  Fabric.Description Blade.Size Color Other.Notes Setup.Time.In.Minutes Time.Over.3.Hr.Goal
1               #N/A          2   321          BR                   124                   0
2               #N/A          2   107                                90                   0
3               #N/A          2   627                               215                   1
4               #N/A          2   206                               436                   1
5 A1 - Originale 2in          2  1032                               105                   0
6 A1 - Originale 2in          2  1056                               116                   0
  Over60
1      1
2      1
3      1
4      1
5      1
6      1

But I know the str_detct function works.

str_detect(HD$Fabric.Description[2803], 'Room Darkening')
[1] TRUE

Any help would be awesome!

Ronak Shah · Accepted Answer · 2021-02-12 04:48:03Z

1

Seems like a good use case for case_when which is vectorized so you don't need for loop.

library(dplyr)
library(stringr)

HD <- HD %>%
  mutate(Type = case_when(str_detect(Fabric.Description, 'RD|Room Darkening') ~ "RD", 
                          str_detect(Fabric.Description, 'LF|Light Filtering') ~ "LF", 
                          TRUE ~ 'Other'))

As far as your code is concerned it should work if you have initialised the column.

HD$Type <- NA

edited Feb 12, 2021 at 4:48

answered Feb 12, 2021 at 4:38

Ronak Shah

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1 Comment

Josh Ortega Over a year ago

Thank you @Ronak Shah and StatsStudent. I was also using the double '==' in my code. ugh

StatsStudent · Accepted Answer · 2021-02-12 04:52:58Z

1

I think it's easier to use dplyr here mutate. This should do the trick and is easier to read:

HD %>% mutate(Type = case_when(str_detect(Fabric.Description, "Room Darkening") == 1  ~ "RD",
                               str_detect(Fabric.Description, "Light Filtering") == 1 ~ "LF",
                     TRUE ~ "Other"))

answered Feb 12, 2021 at 4:52

StatsStudent

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