Function reference

Strings

String manipulation functions.

nchar	Return the number of characters in a string. Vectorised.
nzchar	Return True if string is non-empty. Vectorised.
paste	Concatenate vectors element-wise with sep, like R’s paste().
paste0	paste() with sep=’’. Equivalent to R’s paste0().
grepl	Return True/False for each element of x matching pattern. Vectorised.
grep	Return indices (0-based) of elements in x matching pattern.
gsub	Replace all matches of pattern in x with replacement. Vectorised.
sub	Replace the first match of pattern in x with replacement. Vectorised.
trimws	Strip whitespace from strings. which: ‘both’, ‘left’, ‘right’. Vectorised.
toupper	Convert string to uppercase. Vectorised.
tolower	Convert string to lowercase. Vectorised.
startsWith	Return True if x starts with prefix. Vectorised.
endsWith	Return True if x ends with suffix. Vectorised.
strsplit	Split string x by split pattern. Returns list of lists. Vectorised.
substr	Extract substring from start to stop (0-based, inclusive). Vectorised.
chartr	Replace characters in old with corresponding characters in new. Vectorised.
formatC	Format numbers as strings. Vectorised.

Vectors

Vector manipulation functions.

which	Return 0-based indices where x is True, like R’s which() but Python-indexed.
which_min	Return 0-based index of the minimum value.
which_max	Return 0-based index of the maximum value.
diff	Return lagged differences of x.
cumsum	Cumulative sum.
cumprod	Cumulative product.
cummax	Cumulative maximum.
cummin	Cumulative minimum.
rev	Reverse a list.
duplicated	Return boolean list: True where element has appeared earlier.
setdiff	Elements in x not in y, preserving order.
intersect	Elements in both x and y, preserving order of x.
union	Unique elements from x and y combined, preserving order.
unique	Return unique elements preserving order.
seq_along	Return 0-based indices along x, like R’s seq_along() but Python-indexed.
seq_len	Return 0-based sequence of length n, like R’s seq_len() but Python-indexed.
seq	Generate a sequence, like R’s seq(), but 0-based by default.
r_range	Return [min, max] of x, like R’s range().

Math

Math operations.

sign	Return -1, 0, or 1. Vectorised.
trunc	Truncate toward zero. Vectorised.
ceiling	Ceiling. Vectorised.
floor	Floor. Vectorised.
sqrt	Square root. Vectorised.
log	Natural log, or log to given base. Vectorised.
log2	Log base 2. Vectorised.
log10	Log base 10. Vectorised.
exp	e^x. Vectorised.
abs	Absolute value. Vectorised.
var	Sample variance (ddof=1), like R’s var().
sd	Sample standard deviation, like R’s sd().
mean	Arithmetic mean. Like R’s mean().
median	Median. Like R’s median().
quantile	Sample quantiles, like R’s quantile().
scale	Centre and/or scale x, like R’s scale().
round	Round x to digits decimal places, like R’s round().

Files

File and path utilities.

list_files	List files in a directory, like R’s list.files().
file_exists	Return True if file exists. Like R’s file.exists().
dir_exists	Return True if directory exists. Like R’s dir.exists().
basename	Return filename component of path. Like R’s basename().
dirname	Return directory component of path. Like R’s dirname().
file_path	Construct file paths, like R’s file.path().

Table

Tabulation functions.

table	Frequency table of x, sorted by name, like R’s table().
prop_table	Proportional frequency table, like R’s prop.table().
margin_table	Marginal sums of a contingency table (dict).

Functional

Functional programming helpers.

lapply	Apply func to each element of x, return list. Like R’s lapply().
sapply	Apply func to each element of x, simplify if possible. Like R’s sapply().
vapply	Like sapply() but checks that each result is of expected_type.
tapply	Apply func to subsets of x grouped by index. Like R’s tapply().
rapply	Recursively apply func to all non-list elements in a nested list.
Filter	Return elements of x for which func returns True. Like R’s Filter().
Map	Apply func element-wise across args. Like R’s Map().
Reduce	Reduce x with func. Like R’s Reduce().

Inspect

Inspection and summary functions.

head	Return first n elements, like R’s head().
tail	Return last n elements, like R’s tail().
length	Length of x, like R’s length().
nrow	Number of rows of a list-of-lists. Like R’s nrow().
ncol	Number of columns of a list-of-lists (assumes rectangular). Like R’s ncol().
dim	Return [nrow, ncol] of a list-of-lists. Like R’s dim().
summary	Basic numeric summary, like R’s summary() on a numeric vector.
rstr	Compact display of object structure, loosely like R’s str().

Utils

Utility helpers.

vec	Wrap a list or tuple in a vectorised Vec object.