我創建了一個函式來列印 tibble 的指定的列塊和行塊，它通常作業得很好。有一個小問題我想不通。當我有一個較小的資料集并想要列印所有列（在指定的行范圍內）時，如果我將列數指定為引數，則不會列印任何內容。但是，如果我指定少一列，它會列印，但會在控制臺中分成兩組行。在這種情況下，我希望能夠查看一行中的所有資料。
我的功能和一些測驗資料如下：
# Need to specify:
# 1.Dataframe name
# 2.Number of cols to print in a block
# 3.Start row
# 4.End row
print_cols <- function(df, ncols, rowstart, rowend) {
numcols <- length(df)
i <- 1
while (i (ncols-1) < numcols) {
cat("\n")
print(paste0("Columns ", i, " to ", (i (ncols-1)), ": Rows ", rowstart, " to ", rowend))
print(df[rowstart:rowend, i:(i (ncols-1))], n = Inf)
i <- i ncols
if (i (ncols-1) >= numcols) {
cat("\n")
print(paste0("Columns ", i, " to ", numcols, ": Rows ", rowstart, " to ", rowend))
print(df[rowstart:rowend, i:numcols], n = Inf)
}
}
}
# Simulate data and test function
# Print blocks of cols (when many variables)
dat <- rep(rnorm(50, 50, 20), 100)
dat <- as_tibble(matrix(data = dat, nrow = 50, ncol = 100, byrow = F))
print_cols(dat, 20, 20, 40) # works fine
# Print all columns (when only a few variables)
dat2 <- rep(rnorm(50, 50, 20), 10)
dat2 <- as_tibble(matrix(data = dat2, nrow = 50, ncol = 10, byrow = F))
print_cols(dat2, 10, 20, 40) # prints nothing - WHY??
print_cols(dat2, 9, 20, 40) # need to specify one column less in order to print```
uj5u.com熱心網友回復：
以下是我將如何重寫您的函式：
print_cols = function(df, ncols, rowstart, rowend) {
if(!is_tibble(df)) {df = as_tibble(df)}
col_starts = seq(from = 1, to = ncol(df), by = ncols)
for(i in col_starts) {
cat("\n")
if(i < tail(col_starts, 1)) {
cols = i 0:(ncols - 1)
} else { ## last iteration
cols = i:ncol(df)
}
message(sprintf(
"Columns %s to %s: Rows %s to %s",
cols[1], tail(cols, 1),
rowstart, rowend
))
print(df[rowstart:rowend, cols], n = Inf)
}
}
print_cols(mtcars, 8, 2, 3)
# Columns 1 to 8: Rows 2 to 3
# # A tibble: 2 × 8
# mpg cyl disp hp drat wt qsec vs
# <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
# 1 21 6 160 110 3.9 2.88 17.0 0
# 2 22.8 4 108 93 3.85 2.32 18.6 1
#
# Columns 9 to 11: Rows 2 to 3
# # A tibble: 2 × 3
# am gear carb
# <dbl> <dbl> <dbl>
# 1 1 4 4
# 2 1 4 1
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