# CoCA: Concept Class Analysis

#### 2022-08-17

    library(text2map)

Concept Class Analysis (CoCA) is a method for grouping documents based on the schematic similarities in their engagement with multiple semantic directions (as measured in the previous section). This is a generalization of Correlational Class Analysis for survey data. We outline this method in more detail in our Sociological Science paper, “Concept Class Analysis: A Method for Identifying Cultural Schemas in Texts.”

The first step to use CoCA is build two or more semantic directions. For example, here are three semantic directions related to socio-economic status. Note that you must load or create word embeddings.

        # build juxtaposed pairs for each semantic directions
        pairs_01 <- data.frame(additions  = c("rich", "richer", "affluence", "wealthy"),
                               substracts = c("poor", "poorer", "poverty", "impoverished") )

        pairs_02 <- data.frame(additions  = c("skilled", "competent", "proficient", "adept"),
                              substracts = c("unskilled", "incompetent", "inproficient", "inept") )

        pairs_03 <- data.frame(additions  = c("educated", "learned", "trained", "literate"),
                               substracts = c("uneducated", "unlearned", "untrained", "illiterate") )

        # get the vectors for each direction
        sd_01 <- get_direction(pairs_01, my_wv)
        sd_02 <- get_direction(pairs_02, my_wv)
        sd_03 <- get_direction(pairs_03, my_wv)

        # row bind each direction
        sem_dirs <- rbind(sd_01, sd_02, sd_03)

Next, we feed our document-term matrix, word embeddings matrix, and our semantic direction data.frame from above to the `CoCA` function:

      classes <- CoCA(my_dtm, wv = my_wv, directions = sem_dirs)
      print(classes)

Finally, using the `plot()` function, we can generate simple visualizations of the schematic classes found:

      # this is a quick plot.
      # designate which module to plot with `module = `
      plot(classes, module=1)