如何基于DF1-DF4的NROW值创建含统计列的新DataFrame

Hey there! Let's put together that DataFrame you need step by step. First, I'll clarify the values and fix the minor naming mix-up where you reused C for both Z's row count and DF3's row count.

Step 1: Define the Row Counts #

First, let's assign the row counts you calculated to clear, non-conflicting variables:

# Row counts from your original DataFrames
A_nrow <- 100  # NROW(DF1)
B_nrow <- 80   # NROW(DF2)
Z_nrow <- 30   # NROW(Z) (you initially labeled this as C)
C_nrow <- 50   # NROW(DF3)
D_nrow <- 25   # NROW(DF4)

Step 2: Construct the Custom DataFrame #

We'll build the DataFrame using your specified calculation rules. For the Z row, I used the explicit values you provided (15 for Count and Count2) since the formula you mentioned (Count2-Nrow(Z)) would result in a negative number that doesn't align with your desired 15 value:

# Create the data frame with all required columns
custom_df <- data.frame(
  DF = c("A", "B", "Z", "C", "D"),
  Count = c(
    A_nrow,
    B_nrow,
    15,  # Explicit value per your requirement
    C_nrow,
    D_nrow
  ),
  Count2 = c(
    0,
    A_nrow - B_nrow,  # A - B = 100 - 80
    15,  # Explicit value per your requirement
    B_nrow - C_nrow,  # B - C = 80 - 50
    C_nrow - D_nrow   # C - D = 50 - 25
  ),
  Percentage = c(
    0,
    (A_nrow - B_nrow)/A_nrow * 100,  # 20/100 = 20%
    15/(A_nrow - B_nrow) * 100,      # 15/20 = 75%
    (B_nrow - C_nrow)/B_nrow * 100,  # 30/80 = 37.5%
    (C_nrow - D_nrow)/C_nrow * 100   # 25/50 = 50%
  )
)

# Format the Percentage column to show % sign
custom_df$Percentage <- paste0(custom_df$Percentage, "%")

Step 3: View the Result #

When you run the code above, you'll get exactly the DataFrame you need:

print(custom_df)
#   DF Count Count2 Percentage
# 1  A   100      0        0%
# 2  B    80     20       20%
# 3  Z    15     15       75%
# 4  C    50     30     37.5%
# 5  D    25     25       50%

内容的提问来源于stack exchange，提问作者user9211845