Display the salient items for each factor

A factor is a summary variable standing in for a group of items that move together. A loading is the correlation between an item and a factor. Returns, per level and factor, the items whose absolute loading meets or exceeds cut, sorted by descending absolute loading. This gives a concise reading of "what each factor is about" without printing a full item-by-factor matrix, which does not scale well to large k or many items.

Usage

top_items(
  x,
  level = NULL,
  cut = 0.3,
  n = NULL,
  sort = TRUE,
  by = c("factor", "item"),
  show_labels = TRUE
)

Arguments

x: An ackwards object.
level: Integer vector selecting which level(s) to include. NULL (default) returns all levels.
cut: Absolute-loading threshold. Items with |loading| >= cut are shown. Default 0.3, matching the cut_show plotting default.
n: Maximum number of items to show per factor. NULL (default) shows all items meeting the cut. When set, the top-n items by |loading| are kept after applying the cut.
sort: Logical. When TRUE (default), items within each group are ordered by descending |loading|. Set to FALSE to keep the original order (useful when items have a meaningful sequence).
by: One of "factor" (default) or "item". Option "factor" groups the listing by factor, giving the salient items of each factor, which answers "what is this factor about?". Option "item" inverts the grouping, so for each item it lists the factors it loads on. That makes cross-loadings legible, and answers "where does this item go?". Both n and sort apply within whichever unit by selects.
show_labels: Logical. When TRUE (default) and the data carried a variable-label attribute at fit time (see ackwards()), items are shown as id: label. Items without a label fall back to the bare id. Set to FALSE to always show the bare m{k}f{j}-style item ids.

Value

An object of class "top_items". Print it for a grouped cli listing. The underlying data frame (one row per selected item) is accessible via $data and contains columns level, factor, item, and loading (plus label when labels are available). The values equal the corresponding tidy(x, what = "loadings") rows (after filtering and optional sorting).

Details

Loadings are signed and reflect the object's primary-parent sign alignment (see ackwards()). Items near the cut threshold may appear for one sign orientation but not the other. That is expected and informative.

If factor labels have been attached, the factor dimension is shown as label (id) wherever it appears. That covers the group headers under by = "factor" and the body entries under by = "item".

Examples

# Fit the raw dataset (not na.omit(), which would drop the column
# attributes): bfi25's IPIP item labels are then captured and printed as
# `code: label`. `missing = "listwise"` handles the NAs cleanly. A 10-item
# subset keeps the example fast; use all items in practice.
x <- ackwards(bfi25[, 1:10], k_max = 3, cor = "polychoric", missing = "listwise")
top_items(x)
#> 
#> ── Salient items by factor (ackwards) ──────────────────────────────────────────
#> Engine: pca
#> Cut: |loading| >= 0.3
#> Top-n: all
#> 
#> ── Level 1 (1 factor) ──
#> 
#> m1f1
#> A3: Know how to comfort others [0.683]
#> C4: Do things in a half-way manner [-0.652]
#> A2: Inquire about others' well-being [0.648]
#> A5: Make people feel at ease [0.634]
#> C5: Waste my time [-0.628]
#> C2: Continue until everything is perfect [0.614]
#> A4: Love children [0.593]
#> C3: Do things according to a plan [0.572]
#> C1: Am exacting in my work [0.554]
#> A1: Am indifferent to the feelings of others [-0.407]
#> 
#> ── Level 2 (2 factors) ──
#> 
#> m2f1
#> C4: Do things in a half-way manner [-0.773]
#> C2: Continue until everything is perfect [0.738]
#> C1: Am exacting in my work [0.734]
#> C5: Waste my time [-0.699]
#> C3: Do things according to a plan [0.657]
#> 
#> m2f2
#> A3: Know how to comfort others [0.846]
#> A2: Inquire about others' well-being [0.786]
#> A5: Make people feel at ease [0.737]
#> A1: Am indifferent to the feelings of others [-0.626]
#> A4: Love children [0.567]
#> 
#> ── Level 3 (3 factors) ──
#> 
#> m3f1
#> C4: Do things in a half-way manner [-0.801]
#> C1: Am exacting in my work [0.740]
#> C5: Waste my time [-0.711]
#> C2: Continue until everything is perfect [0.701]
#> C3: Do things according to a plan [0.636]
#> 
#> m3f2
#> A3: Know how to comfort others [0.812]
#> A5: Make people feel at ease [0.762]
#> A4: Love children [0.728]
#> A2: Inquire about others' well-being [0.644]
#> 
#> m3f3
#> A1: Am indifferent to the feelings of others [-0.876]
#> A2: Inquire about others' well-being [0.464]
#> ────────────────────────────────────────────────────────────────────────────────
#> Loadings reflect primary-parent sign alignment. Use tidy(x, what = "loadings")
#> for the full matrix.
top_items(x, level = 3, cut = 0.4, n = 5)
#> 
#> ── Salient items by factor (ackwards) ──────────────────────────────────────────
#> Engine: pca
#> Cut: |loading| >= 0.4
#> Top-n: 5
#> 
#> ── Level 3 (3 factors) ──
#> 
#> m3f1
#> C4: Do things in a half-way manner [-0.801]
#> C1: Am exacting in my work [0.740]
#> C5: Waste my time [-0.711]
#> C2: Continue until everything is perfect [0.701]
#> C3: Do things according to a plan [0.636]
#> 
#> m3f2
#> A3: Know how to comfort others [0.812]
#> A5: Make people feel at ease [0.762]
#> A4: Love children [0.728]
#> A2: Inquire about others' well-being [0.644]
#> 
#> m3f3
#> A1: Am indifferent to the feelings of others [-0.876]
#> A2: Inquire about others' well-being [0.464]
#> ────────────────────────────────────────────────────────────────────────────────
#> Loadings reflect primary-parent sign alignment. Use tidy(x, what = "loadings")
#> for the full matrix.

# Invert the grouping to read cross-loadings item-by-item
top_items(x, level = 3, cut = 0.25, by = "item")
#> 
#> ── Salient factors by item (ackwards) ──────────────────────────────────────────
#> Engine: pca
#> Cut: |loading| >= 0.25
#> Top-n: all
#> 
#> ── Level 3 (3 factors) ──
#> 
#> A1: Am indifferent to the feelings of others
#> m3f3 [-0.876]
#> 
#> A2: Inquire about others' well-being
#> m3f2 [0.644]
#> m3f3 [0.464]
#> 
#> A3: Know how to comfort others
#> m3f2 [0.812]
#> m3f3 [0.287]
#> 
#> A4: Love children
#> m3f2 [0.728]
#> 
#> A5: Make people feel at ease
#> m3f2 [0.762]
#> 
#> C1: Am exacting in my work
#> m3f1 [0.740]
#> 
#> C2: Continue until everything is perfect
#> m3f1 [0.701]
#> m3f2 [0.269]
#> 
#> C3: Do things according to a plan
#> m3f1 [0.636]
#> 
#> C4: Do things in a half-way manner
#> m3f1 [-0.801]
#> 
#> C5: Waste my time
#> m3f1 [-0.711]
#> ────────────────────────────────────────────────────────────────────────────────
#> Loadings reflect primary-parent sign alignment. Use tidy(x, what = "loadings")
#> for the full matrix.