transpose

transpose(X)

Alias: flip

X is a tuple/matrix/table/dictionary/array vector/columnar tuple.

• If X is a tuple, all elements must be vectors of the same length.
• If X is an array vector or columnar tuple, the number of elements in each row must be the same.

This function is used to transpose X:

• If X is a tuple: return a tuple of the same length as each element of X. The n-th element of the result is a vector composed of the n-th element of each element of X.

• If X is a matrix: return the transpose of X.

• If X is a table: convert X into an ordered dictionary. The dictionary keys are column names. Each dictionary value is a vector of the corresponding column.

• If X is a dictionary: convert X into a table. The dictionary keys must be of STRING type:
  • When values are scalars or vectors of equal length, the keys of X serve as the column names and the cooresponding values populate the column values in the table.
  • When the values are dictionaries, the resulting table will have the keys of X as the first column (named "key"). Subsequent columns will be derived from the keys of the first sub-dictionary with each row populated by corresponding values from all nested dictionaries. Missing keys in any sub-dictionary will result in null values in the table.
  Note: Dictionaries with more than 32,767 keys cannot be converted into a table.
• If X is an array vector or columnar tuple: switch data from columns to rows, or vice versa.

Example 1: transpose of a tuple:

x=(`A`B`C,1 2 3);
x.transpose();
// output: (("A",1),("B",2),("C",3))

Example 2: transpose of a matrix:

x=1..6 $ 3:2;
x;

transpose x;

Example 3: convert a table into a dictionary:

timestamp = [09:34:07,09:36:42,09:36:51,09:36:59,09:32:47,09:35:26,09:34:16,09:34:26,09:38:12]
sym = `C`MS`MS`MS`IBM`IBM`C`C`C
price= 49.6 29.46 29.52 30.02 174.97 175.23 50.76 50.32 51.29
qty = 2200 1900 2100 3200 6800 5400 1300 2500 8800
t = table(timestamp, sym, qty, price);
t;

transpose(t);
/*
timestamp->[09:34:07,09:36:42,09:36:51,09:36:59,09:32:47,09:35:26,09:34:16,09:34:26,09:38:12]
sym->[C,MS,MS,MS,IBM,IBM,C,C,C]
qty->[2200,1900,2100,3200,6800,5400,1300,2500,8800]
price->[49.6,29.46,29.52,30.02,174.97,175.23,50.76,50.32,51.29]
*/

Example 4: convert a dictionary into a table:

z=dict(`id`val,[`a`b`c,1 2 3]);
z;
/*
val->[1,2,3]
id->[a,b,c]
*/
transpose(z);

// When the value of a dictionary contains both a scalar and a vector, the scalar will be automatically filled to match the length of the vector.
z1=dict(`id`val,[`a,1 2 3]);
z1;
transpose(z1)

Example 5: convert a nested dictionary into a table.

d = {'tag1':{'val1':2,'val2':6},'tag2':{'val2':1, 'val3':3}}
d
/*
tag1->
    val1->2
    val2->6

tag2->
    val2->1
    val3->3
*/
transpose(d)

The result shows that after converting the dictionary d into a table, it includes a "key" column and columns named after the keys of the first sub-dictionary (val1 and val2). The "key" column contains the keys (tag1 and tag2) from d, while the val1 and val2 columns hold the corresponding values from the sub-dictionaries. Since sub-dictionary tag2 lacks val1 key, the corresponding value is null. Additionally, its val3 key is excluded from the resulting table, and the corresponding value is discarded.