3.16 Pipes: Tee Pipe Intermediate Results

20220511 The tee-pipe comes in handy with base::assign()ing intermediate results into a variable without breaking the main flow of the pipeline. In the following example the variable tmp has an intermediate value assigned to it within the base::globalenv() so that we can access it from anywhere in the R session.

ds %>%
  select(rainfall, min_temp, max_temp, sunshine) %>%
  filter(rainfall==0) %T>%
  assign("tmp", ., globalenv()) %>%
  select(min_temp, max_temp, sunshine) %>%
  summary()

##     min_temp        max_temp        sunshine    
##  Min.   :-8.70   Min.   :-2.10   Min.   : 0.0   
##  1st Qu.: 7.30   1st Qu.:19.60   1st Qu.: 6.8   
##  Median :12.00   Median :24.40   Median : 9.6   
##  Mean   :12.02   Mean   :24.78   Mean   : 8.7   
##  3rd Qu.:16.80   3rd Qu.:29.80   3rd Qu.:11.1   
##  Max.   :33.90   Max.   :48.90   Max.   :14.5   
##  NA's   :612     NA's   :676     NA's   :76973

We can now access the variable tmp:

print(tmp)

## # A tibble: 135,572 × 4
##    rainfall min_temp max_temp sunshine
##       <dbl>    <dbl>    <dbl>    <dbl>
##  1        0      7.4     25.1       NA
##  2        0     12.9     25.7       NA
##  3        0      9.2     28         NA
##  4        0     14.3     25         NA
##  5        0      7.7     26.7       NA
##  6        0      9.7     31.9       NA
##  7        0     13.4     30.4       NA
##  8        0      8.4     24.6       NA
##  9        0     14.1     20.9       NA
## 10        0      9.8     25.6       NA
## # … with 135,562 more rows

Notice that for a tee-pipe curly braces will often be used to encapsulate a sequence of operations for the first path of the tee-pipe, allowing reference the data from the pipeline as the period (.).

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